©PROJECT OCEANOGRAPHY
SPRING 2000
SOUNDS OF THE SEA
Table of Contents
Table of Contents
How to Use this Packet
Florida Standards Curriculum Alignment
Sounds of the Sea Acknowledgements
Sounds of the Sea Packet Contents
Show Host
pg. 39
pg. 41
pg. 42
pg. 43
pg. 44
pg. 45
Unit 2. Sounds of the Sea
Lesson 1. Introduction to Marine Mammals and
Acoustics.
pg. 46
What is Sound?
pg. 46
Introduction to Basic Acoustics
pg. 47
pg. 47
How does Sound Move?
Why Study Acoustical Oceanography
pg. 49
Introduction to Marine Mammals
pg. 50
pg. 51
How Echolocation Works for Marine Mammals
Activities
Activity 1-1. How Fast does a Wave Travel?
pg. 53
Activity 1-2. How do we Hear?
pg. 55
pg. 56
Activity 1-3. Sing Ladies and Gentlemen.
Student Information Sheet Lesson 1. Introduction to Marine Mammals and
pg. 57
Acoustics
Lesson 2. Listening and Looking at Sounds
Sound Production
pg. 60
Diagram 2-1. Dolphin Head
pg. 61
Sound Reception
pg. 61
pg. 62
Diagram 2-2. Human Ear
How do Marine Mammals (and other organisms) use Sound in the Water?
pg. 62
Activities
Activity 2-1. Listening Skills
pg. 64
pg. 65
Activity 2-2. Mathematical Magnitudes
Student Information Sheet Lesson 2. Sound Production and Reception
pg. 67
pg. 68
Teacher Information Sheet
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
Lesson 3. Sound Use by Marine Mammals
Functions and Uses of Sound
pg. 69
Applications of Sound in the Ocean
pg. 71
Activities
Activity 3-1. Target Size
pg. 72
Activity 3-2. Ocean Scramble
pg. 74
Student Information Sheet Lesson 3. Sound Use by Marine Mammals
pg. 75
Lesson 4. Sounds People use to Explore
the Oceans
Vessels and Vehicles
• Vessels
• Satellites
• Robots
• Buoys and Probes
Sound Used in Ocean Research
Future of Ocean Research
Activities
Activity 4-1. Phone a Friend
Activity 4-2. Play the Table Settings
Student Information Sheet Lesson 4. How to Live on a Ship
Lesson 5. Sound Pollution in the Ocean
pg. 76
pg. 76
pg. 76
pg. 77
pg. 78
pg. 78
pg. 79
pg. 80
pg. 81
pg. 82
pg. 83
pg. 84
pg. 84
pg. 84
pg. 85
pg. 86
What is Noise Pollution?
How is Noise Pollution Harmful?
Hearing Loss in Humans and Marine Mammals
Specifics of Hearing
Activities
Activity 5-1. How Loud is Too Loud?
pg. 87
pg. 88
Activity 5-2. Making Sounds
Student Information Sheet Lesson 5. How Loud is What You Hear?
pg. 90
Lesson 6. Recording Sounds from Wild Marine Mammals
Problems Researchers Face
pg. 91
pg. 92
Tools Developed to Solve Recording Problems
A Deeper Look
pg. 93
Activity
pg. 94
Activity 6-1. Listen to the Noise
Student Information Sheet Lesson 6. Fun and Interesting Facts about
pg. 95
Sound
pg. 96
Vocabulary
pg. 99
References
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
How to use this Packet
Dear Educator:
This packet contains background information for teachers and students, as
well as student activities, references, and resources for further study. The
first pages of each lesson are background materials for the teachers.
These may be read aloud to students, copied and distributed for advanced
students, or used as an introduction for discussion on the topics to be
covered in the video lesson. When used with students before each
broadcast, these materials will familiarize the students with vocabulary
words and new concepts. It may also contain more detailed information not
covered in the video lesson, and will aid successful completion of follow-up
activities and promote richer follow-up discussions.
The student activities are intended for use following the video lesson.
Depending on student grade level, they may require assistance from the
teacher.
Finally, a student information sheet is provided for each lesson. This
background material is written to be simpler and more easily read than the
teacher material and is intended for students to read on their own. It
should be copied and distributed to students before the video presentation.
The student sheet might consist of fun facts about the lesson, a matching
activity or other materials that would intrigue students to begin thinking
about the lesson and to have as a reference during and after the video
lesson. It also contains a short list of resources so students who become
interested in a subject can continue researching this topic or prepare a
science project.
Thanks for your help, and have a great semester! If any questions or
concerns arise, please feel free to contact us at 1-888-51-OCEAN or
[email protected]
Enjoy!
The Project Oceanography Staff
The background materials and activities for Unit 3, Acoustic Oceanography were
designed with the idea that they would be inter-disciplinary. Each unit and
activity will link into one or more of the following: mathematics, geography,
English, art, chemistry, spelling and marine biology.
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
FLORIDA CURRICULUM STANDARDS ALIGNMENT
SCIENCE
STRAND
• energy
• properties of waves
• motion of objects
• life is correlated with positive and negative human behavior
• advancement of technology
STANDARDS
• understands different units and energies
• knows the parts of a wave
• knows that sound travels in different media at different speeds
• understands the need for protection of the environment
• knows positive and negative consequences of human action on the Earth’s
systems
• knows behavior is a response to environment
• knows that advancement of science and mathematics generates new
technology
MATHEMATICS
STRAND
• concrete and symbolic representation of numbers and symbols
• operations of numbers and computes for problem solving
• selects appropriate equation to solve problems
Standards
• can interpret symbols and relate them to an equation or form applicable to the
example
• show addition, multiplication, division, and subtraction
• choose appropriate operation to solve real world problems and can solve
adequately
LANGUAGE ARTS
STRAND
• reading
• clear verbal and written communication
• analyze words from text and draw conclusions
• comprehension of main idea
STANDARD
• makes generalizations and inferences from text
• draws conclusion from note making or summarizing
• summarization of text topics
• organized presentation of ideas
• uses variety of print and electronic sources for more information and research
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
Sounds of the Sea
The Staff at Project Oceanography would like to thank the
following people for their assistance in preparing this packet:
Executive Producer:
Paula Coble, Ph.D.
Graphics: Chad Edmisten
Juli Rasure
Writers:
Juli Rasure
Douglas Nowacek, Ph.D.
Edited by:
Tracy Christner
Paula Coble, Ph.D.
Douglas Nowacek, Ph.D.
Packet Distribution: Tracy Christner
Lori Pillsbury
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
Sounds of the Sea Packet Contents
Sounds of the Sea Sunshine State Standards:
• Populations and Ecosystems
• Diversity and Adaptations
• Resources and Technology
A. Overview
1. Sounds of the Sea
In the next six lessons students will learn about marine
mammals and how they communicate, navigate, and locate
food. Resources and technology used to study these amazing
animals will be discussed. Topics and vocabulary within each
lesson will be discussed during each broadcast; as well as,
within the teachers’ educational materials.
2. Contents of Package
Your packet contains the following lessons:
Introduction to Marine Mammals and Acoustics
Listening and Looking at Sounds
Sound Use by Marine Mammals
Sounds People Use to Explore the Oceans
Sound Pollution in the Ocean
Recording Sounds from Wild Marine Mammals
Your packet contains the following activities:
How Fast Does a Wave Travel
How Do We Hear?
Sing Ladies and Gentlemen
Listening Skills
Mathematical Magnitudes
Target Size
Ocean Scramble
Phone a Friend
Play the Table Settings
How Loud is Too Loud?
Making Sounds
Listen to the Noise
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
Douglas P. Nowacek
Postdoctoral Investigator, Woods Hole
Oceanographic Inst.
Postdoctoral Scientist, Mote Marine
Laboratory
Ph.D. in Biological Oceanography,
MIT/Woods Hole Oceanographic Institute
Douglas Nowacek completed his undergraduate studies in Zoology at
Ohio Wesleyan University in 1991. In 1993 he entered the
MIT/WJ\HOI (Massachusetts Institute of Technology/Woods Hole
Oceanographic Institution) Joint Program in Biological Oceanography
where he studied with Dr. Peter Tyack.
Doug’s Ph.D. research focused on the foraging behavior and use of
biosonar in bottlenose dolphins, Tursiops truncatus. His work
resulted in the first quantitative, detailed accounting of dolphin
foraging behavior, and showed that echolocation is involved in the
foraging sequence. For this work Doug pioneered the use of an
overhead video system which provided continuous footage of animals
below the surface. On the acoustic side Doug worked with Mark
Johnson of the Applied Ocean Physics and Engineering Department
at WHOI to develop an acoustic data logger capable of recording
every click produced by a free-ranging dolphin.
Dr. Nowacek’s primary research interests are: behavioral and
acoustic response of Marine Mammals to anthropogenic Noise,
circumstances surrounding collisions between vessels and
endangered marine mammals, and odontocete foraging behavior and
biosonar.
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
Unit 2. Lesson 1. Introduction to
Marine Mammals and Acoustics
Lesson Objectives:
• Introduce basic acoustic principles and the movement of sound through air and
water.
• Students will gain an understanding of the importance of the study of acoustic
oceanography.
• Students will gain an understanding of why and how marine mammals use sound.
Vocabulary: sound, acoustics, medium, amplitude, pitch, frequency
What is Sound?
Sound has
many
definitions.
The most
familiar one is
a noise, vocal
utterance, or
musical tone.
Although most
ideas of sound center on
something that is heard by the
human ear, it can have many
other definitions. For example,
it can mean secure and
reliable. It can also mean a
relatively narrow passage of
water between larger bodies of
water and also a body of water
between the mainland and an
island.
Much can be learned from
studying sound. The military
uses sound to locate ships and
submarines in the water,
researchers use sound to study
the ocean floor, biologists use it
to track marine mammals and
study the ocean floor
(topography). Sound is used
to help make medical
diagnoses. Ships used sound
to avoid obstacles under the
surface of the water. The study
of sound is called acoustics.
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
Introduction to Basic Acoustics
Acoustics is the science that
deals with the creation,
spreading and delivery of
energy in the form of vibrational
waves in air, water or other
medium. Sounds begin as a
vibration that is transferred
through a medium in a series of
waves.
Sound waves travel with certain
intensity called amplitude.
When the amplitude of a sound
increases, the intensity of the
sound increases, as does the
amount of energy that is
transferred.
Another property of sound is
pitch, which is highness or
lowness of a sound. The pitch
depends on the frequency of
the sound waves, or how many
waves pass a given point per
second. The higher the
frequency, the higher the pitch,
and the lower the frequency,
the lower the pitch. An
example of pitch is the roar of a
lion and the chirp of a bird. A
lion’s roar is a low pitch, while
the bird is a high pitch.
An understanding of acoustics
is necessary to understand the
sounds produced by fish and
marine mammals in the ocean,
how fast and far sound can
travel, noise pollution, how
energy moves as sound, and
the things that interfere with
sound signals.
How Does Sound Move?
The movement of sound is in
waves. Amplitude, frequency
(f), and wavelength are
properties used to characterize
waves. Every sound has a
unique set of wavelengths and
frequencies, which are related
to velocity, or the speed at
which sound travels. Sound or
acoustic energy travels best
©PROJECT OCEANOGRAPHY
FALL 2000
through solids and liquids.
Sound travels in sinusoidal
and compressional waves.
Sinusoidal waves look like a
like jump rope moving up and
down or the surface of the
ocean as it is moving.
Compressional waves look like
a slinky moving down a flight of
stairs.
SOUNDS OF THE SEA
Before continuing, let’s discuss the components of a sinusoidal wave,
which are less complicated than those of the compressional wave.
The following figure shows a sinusoidal wave and its components. The
definitions and their components are listed.
trough: the lowest point of a wave
crest: the highest point of a wave
wavelength: the distance between a point on one wave, and the identical point on the
next wave. Expressed as λ.
amplitude: distance from the crest (or trough) of a wave to the rest position of a wave
rest position: the level of the medium the wave is moving through when it’s not in
motion
frequency: number of wave crests (or troughs) that pass a fixed point each second.
Expressed in hertz (Hz). One hertz is the same as one wave per second.
crest
Rest
position
amplitude
trough
one second
Wavelength (λ)
Sound also travels in compressional waves. To see how this works,
hold one end of a slinky and squeeze all of the coils together.
Release one end of the slinky, and allow it to fall. This will produce a
compressional wave. As the wave moves, some of the coils are
squeezed together. This is called compression. Other areas spread
apart and these areas are called rarefaction. As the wave moves, the
rings of the slinky alternate between compression and rarefaction.
The wave carries energy forward, the medium the wave travels
through does not move.
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
rarefaction
compression
wavelength
Figure 1. A compressional wave and its components.
compression: the dense area in a compressional wave
rarefaction: the less dense area of a compressional wave
wavelength: distance between a point on one wave and the identical point on the next
wave
The relationships between the sinusoidal wave and the compressional wave are
that sinusoidal waves are pure sound. For example, it is a continuous sound with
no fluctuation in pitch. A compressional wave represents the sound, or sounds
that humans and animals use to communicate.
Why Study Acoustical Oceanography?
The dramatic sight of the ocean
surface fascinates almost
everyone. What lies beneath
the churning surface? How can
we study the depths of the
ocean? What can be seen
under the dark and mysterious
waters? Without searchlights
and high tech research vessels,
humans are literally “blind as a
bat” under the ocean at depths
greater than 100m.
Bats can
navigate,
communicate
and find food
in the darkness. Bats use
acoustics to do so. They send
out high-pitched sounds to a
target (this may be prey), and
their brains act like
©PROJECT OCEANOGRAPHY
FALL 2000
sophisticated signal
processors. Scientists and
inventors have taken a lesson
from the morphology of animals
to advance the study of sound
in the oceans.
The study of acoustical
oceanography is very important
to the military for detection of
submarines and icebergs, to
oceanographers for ocean
mapping and depth
determination, commercial
fishermen for locating fish and
engineers for
telecommunications through
the ocean. Acoustics has also
helped biologists learn about
the sounds animals make and
how they use them.
SOUNDS OF THE SEA
Introduction to Marine Mammals
Mammals of various types
are found all over the world.
Marine mammals are special
because they depend on the
aquatic environment for
survival. They are found near
continental coastlines all over
the world (including the north
and south poles), and living in
the pelagic realm of the
ocean. Marine mammals
represent three different
orders of animals. They
include the Carnivora (polar
bears, otters, seals, sea lions,
and walruses), the Cetacea
(whales, dolphins, and
porpoises) and the Sirenia
(manatees and dugongs).
Each group is very different,
but they do have many things
in common.
Common characteristics of marine mammals
occupy and depend on aquatic habitats for survival
most have a large body size
streamlined shape compared to terrestrial
relatives
dense fur and blubber for insulation
reduction of appendage size
similar adaptations for diving, orientation and
communication
For the purposes of this unit,
cetaceans will be the main
focus. However, carnivores
and sirenians have also
developed many sounds to
communicate with each other.
These sounds include
squeaks, chirps, whistles,
buzzes and grunts.
The cetaceans (including
dolphins, whales and
porpoises) emit either clicking
sounds or whistles. The clicks
are short pulses of about 300
sounds per second, emitted
from a mechanism located
just below the blowhole.
These clicks are used for the
echolocation of objects.
Cetaceans can explore and
identify their environment by
emitting sounds and
interpreting them when they
bounce back. Nasal air sacs,
sloping maxillary bones, and
the cranium reflect sound
within the animal’s head, and
help focus the sound beam
forward through a structure
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
called the melon. The melon,
composed of fat, transmits
sound to the environment.
The oily melon, which is
located above the forehead,
acts as an acoustic lens to
focus sound in a forward
direction. Fat tissues located
around the lower jaw to the
middle ear transmit echoes
received to the rear of the
lower jaw.
This echolocation system,
similar to that of a bat,
enables the dolphin to
navigate, to detect fish, squid,
and even small shrimp, and it
may be used for
communication by some
species of toothed whales.
The whistles are toned
squeals that may be produced
in the larynx, although they
may come from the same
area as echolocation clicks.
The dolphins use some
whistles to communicate and
maintain contact with other
dolphins.
How Echolocation Works for Marine
Mammals
Sounds produced by animals
for echolocation function as a
kind of biological sonar,
whereas vocalization
sounds—the most famous of
which are the “songs” of the
humpback whale—seem to
function as a means of
communication between
members of the same
species.
By directing sounds produced
in the head region toward an
object and then receiving the
sound waves after they have
bounced off an object, the
animals can make fine
discriminations as to size,
density, distance, and so on.
©PROJECT OCEANOGRAPHY
FALL 2000
Because the sound waves are
waterborne and travel very
efficiently through water,
cetaceans have been able to
discard the external ear that
land mammals developed to
gather airborne sounds. More
details about how a marine
mammal produces and
receives sound will be
discussed in Lesson 2. This
system of sensing the
environment is obviously of
enormous advantage in
orienting, navigating, and
capturing prey in dark or
turbid waters. It is a means of
scanning by sound for the
same information humans and
most other land mammals
SOUNDS OF THE SEA
perceive by vision. On the
other hand, cetaceans do not
necessarily have poor
eyesight.
Echolocation research has
mainly concentrated on the
bottlenose dolphin. Similar
sounds emitted by other
species of cetaceans have
been hypothesized to be
echolocation sounds.
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
Activity 1-1. How Fast Does a Wave
Travel?
Before the speed of a wave can be calculated, the components of a
wave must be understood. See the following table for definitions.
trough: the lowest point of a wave
crest: the highest point of a wave
wavelength: the distance between a point on one wave, and the
identical point on the next wave. Expressed as λ.
amplitude: distance from the crest (or trough) of a wave to the rest
position of a wave
rest position: the level of the medium the wave is moving through when
it’s not in motion
frequency: number of wave crests (or troughs) that pass one place each
second. Expressed in hertz (Hz). One hertz is the same as one wave per
second.
Wave velocity, , describes how fast the wave moves forward. It can be
calculated by multiplying the wavelength and frequency as shown below.
velocity = wavelength x frequency
=λxf
wavelength
crest
rest
position
trough
PROJECT OCEANOGRAPHY
FALL 2000
amplitude
1 second
SOUNDS OF THE SEA
Activity 1-1. How fast does a Wave
Travel (mathematics)?
A. What happens to the wavelength (λ) as the frequency (f)
increases?
B. Calculate the velocity of the following wave.
A wave is generated in the bathtub. The wavelength is 1.5m.
The frequency of the wave is 0.5Hz. What is the velocity of the
wave? Follow this method.
Known information:
wavelength, λ = 1.5m
frequency, f = 0.5 hertz
Another way to express Hertz is 1/second, so,
0.5 hertz = 0.5/second
Unknown information: velocity (v)
Equation to use: v = λ x f
C. Calculate the frequency of the following wave.
An underwater earthquake produces a wave that travels at
250m/s. It has a wavelength about 10 m. What is the frequency
of the wave?
Known information.
velocity, v = 250m/s
wavelength, λ = 10m
Remember, Hz = 1/s, so m/s ÷ m = 1/s = 1 Hz
Unknown information
frequency (f)
Equation to use: f = v ÷ λ
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
Activity 1-2. How Do We hear?
A look inside your ear would reveal a thin membrane stretched
across the end of a short tube that is about the width of a pea.
When sound reaches the ear, the eardrum sets into motion an
arrangement of tiny bones, tubes, hairs and nerves that work
together with the brain to let sound be heard.
Materials:
• an empty frozen juice can
• a can opener
• a balloon
• a rubber band
• glue
• a piece of mirror that is ½ cm square (ask a
glass or hardware store for the scraps)
• a dark room
• a flashlight
Procedure:
1. Remove both ends of the can.
2. Cut the balloon in half across its width.
3. Stretch the balloon over one end of the can so that the balloon is
very taut. A rubberband might be necessary to hold it in place.
4. Glue the mirror to the outside of the stretched balloon about 1 cm
from the edge of the can.
5. Turn out the lights, and shine the flashlight onto the mirror at an
angle, so that a bright spot is reflected from the mirror onto the
wall or ceiling.
6. Shout into the can from the open end. Sing high and low notes,
and speak softly. What happens to the spot on the wall?
HOW IT WORKS
Any sound that is made into the can travels through the air
into the stretched balloon. The sound makes the balloon
vibrate, which in turn makes the mirror vibrate. The
vibrations can be seen in the reflecting light on the wall. Sound
travels in the human ear in a similar way. The sound is collected by
the outer ear, and travels down a small tube, called the ear canal, to
the eardrum. When sound reaches the eardrum, it vibrates just like
the balloon did.
PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
Activity 1-3 Sing Ladies and Gentlemen.
Why do males and females have different sounding voices? Well,
don’t investigate throats and vocal cords. Try this simple
experiment.
Materials:
• medium sized book
• medium sized rubber band
• 2-4 pencils
Procedure:
1. Slide the rubberband lengthwise around the book. Make sure
there are no twists.
2. Slide two pencils under the rubberband, with the sharpened ends
off the end of the book.
3. Pluck the band with a finger. Listen, and watch the rubberband
vibrate.
4. Move the pencil to the middle of the book. Observe the
difference in vibrations, and how the sound differs.
HOW IT WORKS.
When the whole band is plucked, the vibrations are slow.
Slower vibrations give off a lower sound or pitch. Faster
vibrations come from a shorter area, and are of higher pitch. A
female has shorter vocal cords than men do. The vocal cords act
like two rubberbands in a box when a person speaks or sings.
Touch the bony part of the neck and hum. The fronts of each
person’s vocal cords are attached here, and the vibration can be
felt.
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
Student Information Sheet 1:
Introduction to Marine Mammals and
Acoustics
What can you make, but not
see? What travels through
solids but makes no holes in
them? Give up? It’s sound.
The following lessons will
contain information and fun
activities to teach you how
sound moves, as well as how
the study of sound (acoustics)
is used in marine mammal
studies and oceanography.
Sound surrounds us all. Think about waking up every morning.
The following sounds were probably around, but were they really
heard?
the water running in the sink
the alarm going off
the rattle of dishes
juice being poured into a glass
the slam of a door
Some sounds travel in a transverse wave. The highest points of this wave are called
the crest, the lowest are called the troughs. The distance between a point on one wave
and the identical point on the next wave, such as from crest to crest or trough to trough is
called a wavelength.
Other sounds move in a more
complex wave pattern. That
wave pattern is called a
compressional wave. A
spring or a slinky can show
how compressional waves
can be formed. Imagine a
PROJECT OCEANOGRAPHY
FALL 2000
slinky moving down a flight of
stairs going end over end.
Think about how the springs
move close together and then
further apart. As the wave
moves, some of the coils are
squeezed together. This
SOUNDS OF THE SEA
crowded area is called
compression (in the slinky,
when it lands on each step).
The compressed area then
expands, spreading the coils
apart, creating a less dense
compression
Marine mammals are special
because they depend on the
aquatic environment for food,
water, transportation, and
much more. They are found
all over the world (including
the north and south poles).
Others live in the pelagic
realm of the ocean. Marine
mammals represent three
area. This area is called a
rarefaction. In the slinky
demonstration, this is when
the slinky is turning over and
falling to the next step. This
wave carries energy forward.
rarefaction
different orders of animals.
They include the Carnivora
(polar bears, otters, seals, sea
lions, and walruses), Cetacea
(whales, dolphins, and
porpoises) and the Sirenia
(manatees and dugongs).
Each group is very different,
but they do have many things
in common.
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
Common characteristics of marine mammals
occupy and depend on aquatic habitats for survival
most have a large body size
streamlined shape compared to terrestrial relatives
dense fur and blubber for insulation
seduction of appendage size
similar adaptations for diving, orientation and communication
Marine mammals are unique, but have many similarities.
Cetaceans and how they use sound will be the focus for this unit,
even though other groups have also developed many sounds to
communicate with each other. These sounds include squeaks,
chirps, whistles, buzzes and grunts.
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
Unit 2. Lesson 2. Listening and
Looking at Sounds
Lesson Objectives: After completing this lesson and the activities, students will be able
to grasp the basic ideas of how sound is generated and how it is interpreted in
the human and marine mammal ear.
Vocabulary Words: vocal cords, phonating, rostrum, pharynx, and nasal system
Note: Remember the words cetaceans, sirenians, dolphins, whales and manatees will
be used continuously through the unit, referring to marine mammals
Sound Production
Before beginning the study of
how a marine mammal makes
sound, let’s briefly discuss how
humans talk. Humans have
elastic ligaments called vocal
cords attached to the bones in
the throat. When air is passed
over these cords, they vibrate
and make sound. The sound
can be modified in intensity,
and by using the tongue, teeth
and lips in vocalization.
Marine mammals also make
many sounds by vibrating
elastic ligaments (vocal cords)
in the larynx. Passing air
across these ligaments makes
vibrations (much like in the
human body). Actions of the
tongue, teeth, and mouth shape
can alter the sound produced.
The nasal system, the
sinuses, and air sacs found in
the pharynx (pharyngeal air
sacs) also have an effect on the
sound produced. These
structures are set up to provide
a marine mammal with
optimum
ability to
communicate.
Seals, sea
otters, and
polar bears create sounds like
barking, crying, growling and
roaring. Manatees make
squeaky and ragged sounds
using vocal cords. Phonating
(of, or pertaining to making
sound) dolphins do not move
the larynx during high
frequency vocalization. They
actually use a combination of
structures in the nasal system.
These structures include the
nasal plug and the elaborate
nasal air sac system.
The processes marine
mammals use to make and
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
receive sound signals is
complex. Cetaceans in
particular have a very
complicated system of sound
production and propagation.
After the sound is generated, it
must be sent through the
environment, so that other
animals can receive it or so it
can return to the dolphin or
whale to collect information.
Nasal air sacs, sloping
maxillary bones, and the
cranium (it is cup-shaped and
acts like a satellite receiver)
reflect sound within the
animal’s head, and help focus
the sound beam forward
through a structure called the
melon. (Humans do not have
this special structure.) The
melon is composed of fat, and
transmits sounds produced in
the head to the environment.
Sounds pass easily from animal
to head because the densities
in the melon and saltwater are
about equal.
Cranium
an air sac
Maxillary
bone
Sound Reception
Many marine mammals rely on
the reception of sound to
communicate, navigate, and
explore their environment for
things like food and predators.
We have learned that the
making of sounds can be
complex. The reception or
‘hearing’ of sound is also
complex, and it is specialized
for hearing sounds underwater.
See the diagram of the human ear on the following page.
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
1
2
3
Figure 2. All mammalian ears, including those of marine mammals,
have three basic divisions: (1) an outer ear, (2) an air-filled middle ear
with membranes and bony structures, (3) a fluid-filled inner ear with
resonators and sensory cells.
In the cetaceans, the outer ear
has been modified or no longer
exists. In other orders, the
outer ear collects sound. The
middle ear detects the sounds,
and transforms the energy into
mechanical signals with the
bony structures so that they
may be detected by the inner
ear. The inner ear interprets
the mechanical message and
transfers the sound into neural
impulses. Humans detect
sounds in the same manner.
How do Marine Mammals (and other
Organisms) use Sound in the Water?
In understanding how marine
mammals use sound in their
environment, it is important to
remember the basic measures
of sound. These are frequency,
speed, wavelength, and wave
height, which equals the
intensity of the sound. The
speed of sound is directly
related to the density of the
medium. Sound travels faster
in water than in air, because
water is denser than air. The
speed of sound in water is
approximately 1530 m/sec.
The speed of sound in air is
340 m/sec. Sound can travel
approximately five times faster
and greater distance in
seawater than air!
Remember, frequency is the
measure of the number of
waves passing a given point in
a given unit of time. If a marine
mammal emits a sound that
PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
has a low frequency, then the
wavelength will be long.
Sounds having long
wavelengths can travel great
distances. The opposite is true
for a high frequency sound. It
has a short wavelength, and
will travel only short distances
because it does not have a lot
of energy. Low frequency
sounds have a wavelength with
much more energy. These can
travel a long distance.
Figure 2- 1. The top rope represents a sound of high frequency. The
wavelength is short and is used to identify small objects. The bottom rope is a
sound of low frequency, and has a wavelength twice the one on the top. It is
used to identify large objects and is necessary for navigation.
There are reasons that animals
emit sounds of different
frequency. Some of these
include navigation, exploration,
finding food, and hiding from
predators. A sound wave of
low frequency (long
wavelength) is used for
identifying or detecting large
objects or targets. These
objects might be larger animals,
research vessels, underwater
©PROJECT OCEANOGRAPHY
FALL 2000
structures, and even land
masses the size of islands.
High frequency sound waves
(short wavelength) are
necessary to determine the size
of small objects or the fine
detail in a large object. For
more examples of the types of
sound waves that animals emit,
see the Student Information
Sheet for this lesson.
SOUNDS OF THE SEA
Activity 2-1. Listening skills.
If you were asked which of your five senses you use most often, the
obvious answer would be sight. A person without vision, or an animal
that survives by interpreting sound signals alone, must rely on sound
for many things that our eyes do for us every day.
Materials:
• a friend
• a blindfold
• a noise maker (keys, a party toy,
cymbals, etc.)
• a radio or CD player and CD’s
Procedure:
Find that sound. In a quiet room or area, sit down and cover your eyes with the
blindfold. Make sure the ears are uncovered. Have a friend stand in
different locations in the room and make noise with the keys, the toys, etc.
Only make one sound at time in a single location.
• Can you determine where your friend is using the sound signals alone?
What to tune out. Play the CD, or tune the radio to a local talk show. While you
are blindfolded, have a friend tell you a story, or describe what they are
seeing. Turn off the CD player, and then repeat the same story back to
your friend. Remember to include all details.
• Did you find this difficult? That is because you must listen for the
correct sounds. A blind person must discriminate which sounds to
listen to, and which ones to tune out. For example, when a blind
person needs to cross the street, they must be able to determine if
there are any cars coming in their direction.
Seeing like a bat, can you echolocate? While blindfolded, have friends lead
you to a different room or location. A small closet or bathroom will even
work. Have your friend position you in the center of the room and clap
your hands twice.
• Is it possible to tell if you are in a small, medium, or large room?
While blindfolded, stand in front of a large wall. The side of a building will
do, a gymnasium will work. Clap your hands as you walk toward the wall.
• Hopefully, the differences in sound will stop you from bumping into the
wall. The sound from the claps bouncing off the walls will change due
to the distance from the wall. The closer you get, the faster the sound
will return to you.
PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
Activity 2-2. Mathematic Magnitudes
Measurements come in many sizes and forms. Oceanographers use the
metric system to be consistent with other oceanographers around the
world. The Metric System is a unit of measure that is based on a scale of
ten. The following table describes the values used by scientists, as well as
some of the terms that acoustic oceanographers use to describe sound
waves emitted from marine mammals.
Standard Units
Value
a
magnitude
Acoustic units
Length
representative
prefix
Mega-
106
1,000,000
105
100,000
104
10,000
103
1,000
102
100
Meters
101
10
Meters
100
1
Meter
10-1
0.1
Deca-
10-2
0.01
Centi-
10-3
0.001
milli-
Kilo-
frequency in
duration
water
(seconds)
(Hertz)
Megahertz Mega seconds
1000 m =
1.5Hz
kilo second
seconds
1m =
1500 Hertz
1 cm =
150 000Hz
1 mm =
1500 000Hz
seconds
millisecondsa
most important in acoustic measurements
Materials:
• meter stick
• masking tape
• classroom floor
Procedure:
1. Using the meter stick, place a piece of masking tape one-meter in
length on the floor.
2. Explain to the students that for description and visual example,
one meter will represent 1 centimeter.
PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
3. Break the centimeter down into millimeters by placing 10 pieces of
tape in equal distances from each other on the “1 centimeter
measure”
4. Explain to the students that each centimeter cannot only be
broken down into 10 segments, but each millimeter can be broken
down into ten segments as well.
5. Add 10 more pieces of tape between the millimeter marks. These
will represent micrometers.
6. Discuss with the students the magnitude differences of
centimeters, meters and kilometers. Every 10 centimeters makes a
meter, every 1000 meters makes a kilometer, and so on.
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
Student Information Sheet 2. Sound
Production and Reception
Marine mammals make a
variety of sounds. Some
marine mammals produce
sound using a mechanism
similar to the one humans use.
Humans have vocal cords
attached to the bones in the
throat. When air passes over
these cords, they vibrate back
and forth producing sound. All
sounds can be made using the
tongue, teeth, and lips.
Many marine mammals make
sound by vibrating elastic
ligaments in the larynx.
Passing air across these
ligaments makes vibrations.
The nasal system, the sinuses,
and air sacs found in the
pharynx, as well as
movements of the mouth,
tongue and lips alter the
sounds produced.
Nasal air sacs, sloping
maxillary bones, and the
cranium reflect sound within the
animal’s head, and help focus
the sound beam forward
through a structure called the
melon. The melon, composed
of fat, transmits sound to the
environment. The oily melon,
which is located above the
forehead, acts as an acoustic
©PROJECT OCEANOGRAPHY
FALL 2000
lens to focus sound in a forward
direction. Fat tissues located
around the lower jaw to the
middle ear transmit echoes
received to the rear of the lower
jaw.
Cranium
an air sac
Maxillary
bone
All mammalian ears have three
basic divisions: (1) outer ear,
(2) an air-filled middle ear, and
(3) a fluid-filled inner ear that
interprets the sound message
and transfers the message to
the body.
Marine mammals (as well as
other marine animals) use
sound waves in the water for
navigation, exploration,
communication, and hiding
from predators.
SOUNDS OF THE SEA
Teachers Information Sheet
Table 2-1. This table shows the frequency and types of sounds that different animals emit. The sounds are very different
in frequency and type of sound used by each animal.
Examples of animal
Example of
Sounds
Group
Details
Other notes
in the order
frequency (kHz)
emitted
whistles,
high frequency
Some animals emit low or
Bottlenose dolphin
0.8-150
clicks,
sounds
high frequency sounds.
bark, yelps
Odontocetes
Others use
pulsed
a combination of the two in
Commerson’s
low frequency
<10
sounds,
the wild.
dolphin
sounds
clicks
call, songs,
Northern Right
low frequency
Others in group emit
<0.4 others emit
moans,
Whale
sounds
between 0.02 and 3.5
pulses
Mysticetes
songs,
Infrasonic they
shrieks,
this order emits low
Humpback Whale
also produce
0.012-0.4 and 1-4
moans,
frequency sounds
audible sounds
grunts
The Harbor seal has the
clicks, roar,
high and low
widest range of sound
Seals
growl,
frequency
Harbor seal
0.7-150
frequency, most of the
(Phocidae)
grunt,
sounds
other seals in this group
creak
are low frequency animals.
much is still to be learned
squeaks,
Trichechidae
manatee
low frequency
0.6-16
about manatee sound
pulses
emission and reception
©PROJECT OCEANOGRAPHY
FALL 2000
ACOUSTICAL OCEANOGRAPHY
ACOUSTICAL OCEANOGRAPHY
Unit 2. Lesson 3. Sound Use by
Marine Mammals
Lesson Objectives: Upon completion of this lesson, students will have gained the ability
to:
• understand the importance of sound to marine mammals.
• measure frequency, wavelength and the speed at which sound travels
• understand why sound is emitted in different frequencies.
Vocabulary: cognition, navigation, maternal, social structure, echolocation
Functions and Uses of Sound
Sound use by marine mammals
has been studied for many
years. Generally, marine
mammals use sound for
communication, exploration,
advertisement, locating food,
maintaining mother-offspring
bonds, and to identify
individuals with their pod or
group.
Echolocation, defined as the
ability to gain information from
sounds produced by the animal
that bounce off distant objects
and return as echoes, is an
example of how sound is used
by marine mammals. Scientists
have learned that Odontocetes
use echolocation. Often, this
ability allows the animal to
interpret their surroundings with
or without vision. Echolocation
is used over great and small
distances. These echoes
convey much information about
the environment. For example,
a dolphin can detect a small
ball over a football field away, a
distance too great to be seen
by either dolphin or human.
Only a few animals have been
shown to use echolocation.
These include dolphins, bats,
and a few species of birds.
Some of the sounds these
animals produce might be
above or below a human’s
capability to hear. Although
people cannot hear the sounds,
the animals are using them,
and processing them to
visualize objects and target
others for food, or avoidance.
©PROJECT OCEANOGRAPHY
FALL 2000
ACOUSTICAL OCEANOGRAPHY
Echolocation is necessary for
navigation. Sperm whales
locate their favorite food, squid,
by diving with great speed to
depths, where there is relatively
little light. They use
echolocation to determine
where the bottom is, and how
fast they are approaching it.
Finback whales use
echolocation for navigation and
may use the same sounds for
maintaining social structure.
Their sounds can be
transmitted and heard
hundreds of kilometers away.
They can determine if an
underwater volcano or island
might be in their paths, and
they can steer away from them.
Others, such as dolphins, use
echolocation to socialize
between groups of dolphins.
This might be in the form of an
advertisement.
A well-known use of sound is to
help determine and keep social
structure between animals.
Dolphins and whales that travel
together in groups use clicks,
moans, and
©PROJECT OCEANOGRAPHY
FALL 2000
whistles to identify each other
and stay together as a group.
Mother and infant
pairs use a series of whistles to
recognize one another. Most
maternal pairs utilize an
individually distinct call. Both
animals can repeat this call,
and use it when the mother and
the offspring are separated.
Similar calls have also been
observed between animals that
have strong social bonds.
Distinct and identical calls and
whistles can be repeated
between individuals. A playful
or loud whistle or click, or some
kind of sound may inform a
group that a dolphin is coming
towards them saying, “Hey, I
am here.”
Finally, over the years, marine
mammal researchers have
found that another use of sound
is for cognition. Cognition is
the act or process of knowing
something. An example of a
cognitive act is when a dolphin
has been trained to respond to
a cue with a vocalization.
SOUNDS OF THE SEA
APPLICATIONS OF SOUND IN THE OCEAN
The sounds used by marine
mammals provide evidence of
how sound can be used and
what the animals can learn
from them. Humans have used
sounds in the ocean to study
whales, learn migration
patterns, and study geography.
Blue
whales
and
other
baleen whales have the ability
to produce sound so low in
frequency that they are an
octave or more below the
lowest sound the human ear
can hear. Blue whale sounds
last many seconds. Blue
whales commonly emit sounds
that have a frequency of
approximately 17-hertz (Hz).
This corresponds to a sound
wave of about 88 meters long
in water. A wavelength of this
size can travel ocean basins
and can be heard hundreds of
kilometers away. Most likely, a
sound of this frequency is used
for navigation. The wavelength
is very long, and can help to
determine if there are
landmasses in the whales’
path.
Sounds with very long
wavelengths are used to
discriminate large obstacles.
However, they cannot be used
to find small obstacles or fish.
The distance
between the
wavelength is so
long, it can easily
pass over small objects. For an
object to be detected in any
size wavelength it must be 1/51/4 the length of the sound
wavelength emitted. Look at
the following example:
The click from a dolphin can be
heard at 100kHz. It has a
wavelength of approximately
1.5cm, so it is small enough to
discriminate between rocks and
small fish. It can even relay
information about the
environment: whether or not
there are pilings present, or if
the dolphin is swimming in an
open channel.
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
Activity 3-1. Target Size
For animals that use echolocation to detect objects in water or air, it
is necessary for them to use a frequency that is most favorable to the
size of the target. Objects, landmasses or features of an object do
not reflect sound very well, thus, the information is relayed to the
animal incompletely.
Materials:
• paper
• pen
• thinking…..
Procedure:
1. Solve the following equations.
The speed of sound in seawater is approximately 1500m/sec.
The wavelength, λ, of a sound equals the speed of sound, c, divided
by the frequency, f.
Therefore: λ = c/f .
In other words, if λ is 4-5 times the length of the object, the object will
not significantly interrupt or reflect the sound wave.
Example: This suggests sound frequencies on the order of 150 kHz
or higher must be used to detect targets of a size approximately 1cm.
If λ = 1cm = 0.01m and the speed of sound is equal to 1500m/sec.
Then, rearranging the equation λ = c/f , to c/λ=f the numbers fit in as
follows:
(1500m/sec) /0.01m = 150000Hz or 150kHz.
(Remember that there are 1000 hertz in a kilohertz. And hertz are
defined at cycles per second, or in units of 1/sec.)
SOUNDS OF THE SEA
Problem 1:
If an object is 2m in length, what wavelength (λ) is needed to detect
it? Remember, for an object to be detected using sound, it must be
¼ or 1/5 the length of the sound wavelength emitted.
Problem 2:
Determine the length of a squid that a sperm whale is diving for if it is
using a frequency of 1500 cycles/second and the speed of sound in
seawater is 1500m/sec. First, you must determine the wavelength (λ)
that the sperm whale emits to detect the squid. (λ) = c/f
Then, determine the length the squid must be to be detected. A
squid must be ¼ - 1/5 the length of the sound wavelength emitted.
Problem 3:
Determine the speed of sound in the frigid arctic water where Orcas
live during the summer. The Orca generally uses a sound frequency
of approximately 2kHz to warn others of danger. The wavelength of
the sound wave is 0.7 meters.
Answers to Problems 1-3.
1. (2m) x (4) or (2m) x (5). The wavelength must be no more than 8
or 10 meters in length to detect an object that is 2 meters in
length.
2. (1500m/s)/(1500cycles per second) = 1m or 100cm is the length of
the sound wavelength emitted. To determine the length of the
squid that is detected, divided the length of the squid by 4 or 5.
(100cm)/4 or (100cm)/5 = 25cm or 20cm The squid must be
between 20 and 25 cm in length for the wavelength of 100 cm to
detect it.
3. λ=c/f We know f=2000Hz and λ=0.7 m so we can solve for c by
rearranging the equation to be c= λf = (0.7m)(2000Hz) = 1400
m/sec. The speed of sound in cold water is slightly slower than
in warmer water.
DID YOU KNOW?
There are currently seven species of cetaceans in U.S. waters that
are protected under the Endangered Species Act. They are the Blue
whale, the Bowhead whale, the Fin whale, the Humpback whale, the
Northern Right Whale, the Sei whale and the Sperm whale. All seven species are
listed as endangered. Scientists use information gained from their calls to track
them, and monitor their well being.
©PROJECT OCEANOGRAPHY
FALL
2000
SOUNDS OF THE SEA
Activity 3-2. Ocean Scramble.
There are many different words that are used to describe echolocation, and
who uses it. Correctly unscramble the words below, and solve the mystery
word with the underlined letters.
CATEINCOMMU
EAHWL
CCKLI
MMMAAL
LWAVNGEETH
VIRONENMNET
OPD
SHIF
NHLPIOD
LARPO BREA
OODF
AONGR
Now use the underlined letters to solve the mystery word. You should have
the following letters: NIOTCALOOECH
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
Student Information Sheet 3. Sound Use
by Marine Mammals
The sounds that marine
mammals make have
fascinated people and
researchers for years. People
like them so much, that
recordings of marine mammal
sounds, especially whales and
dolphins, have become best
sellers.
Marine mammals use sound for
communication, exploration,
advertisement, locating food,
maintaining pup-mother
interactions, and to identify
individuals within their pod or
group. Some of the animals
produce sounds that are too
low-or too high- pitched for
humans to hear. Some animals
that use sound include
dolphins, bats, fish,
invertebrates, polar bears,
otter, seals and whales.
Echolocation is defined as the
ability to produce high
frequency clicks and to detect
echoes that bounce off distant
objects. Marine mammals use
echolocation to identify other
animals, the environment, and
migration paths. Using
echolocation, mammals have
the ability to ‘see’ their
©PROJECT OCEANOGRAPHY
FALL 2000
surroundings when light and
visibility are low.
Some sounds used by animals
have very long or very short
wavelengths. Sounds with long
wavelengths are used for
navigation, and exploring.
Long wavelengths can travel
hundreds, even thousands of
kilometers. These kinds of
waves are so long, they can
easily pass over small objects.
Therefore, an animal must also
be able to emit shorter
wavelengths. For an object to
interrupt a wavelength, it must
be 1/5-1/4 the length of the
wavelength. Sounds with short
wavelengths are used to learn
about details in the
environment, or to find small
objects.
SOUNDS OF THE SEA
Unit 2. Lesson 4. Sounds People
use to Explore the Oceans
Lesson Objectives: Students will gain knowledge and appreciation for research vessels
and equipment found on them.
Vocabulary words: satellite, Argos, tether, autonomous, buoy, idiophone
Vessels and Vehicles
Vessels
The ocean provides
oceanographers with a difficult
environment to study. Deep
water, high pressure, and low
light all hinder ocean
exploration. In many cases is it
necessary to reach locations far
from land, conduct experiments
over a long period of time, and
bring samples and specimens
back to the onshore
laboratories. How would one go
about studying this vast realm?
Universities and research
institutions have solved the
problem of getting to the area
in the ocean they want to
study by having ships devoted
solely to research processes.
Research vessels roam all
waters of the earth. The ships
are equipped to provide
housing for the researchers,
electronic capability to support
almost any kind of equipment,
and satellite equipment to
transmit data back to land.
Ships are equipped with
winches, cranes, A-frames,
small boats, and other gear to
do over-the-side work. They
also have laboratory space for
sample analyses and data
processing. Most ships stay
out for prolonged periods of
time; several days to several
months, while there are others
that are only capable of
handling a one-day cruise.
Some ships provide a ‘base’
from which
scientists can
work. The
ship serves
as a center to deploy
instruments. Some of these
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
include manned, and
unmanned submersibles,
remotely operated vehicles,
buoys, CTD’s and other sample
collection devices, like bottles
and nets.
At any given time, it might be
possible to find vessels in the
Pacific Ocean, the Polar
Regions, Lake Baikal, and the
Mediterranean Sea, as well as
along coastlines.
SATELLITES
The world’s oceans contain
almost 3,000 drifters, buoys,
and other objects collecting
oceanographic data. These
items are monitored by the only
satellite system dedicated to
monitoring and protecting the
environment. This system is
called Argos. The satellite flies
at a low altitude, which means it
can receive transmissions from
low-power transmitters.
Briefly, the system receives
©PROJECT OCEANOGRAPHY
FALL 2000
transmissions from floating and
deep-sea buoys and other
platforms. The message is
then transmitted back to a land
or ship-based operation. The
land-based scientist can easily
retrieve the data
without removing the
instrument from the
water and data
analysis can begin
immediately using the
Argos system.
The most attractive
aspect of using drifting
buoys and other
platforms that are
monitored by Argos is
that they can operate
unattended for up to
two years, and deepsea floats can operate for up to
four. Argos-monitored systems
are more economical because
expensive ship time and
valuable man-hours are not
necessary.
SOUNDS OF THE SEA
Robots
Advancement in technology
has allowed the use of
unmanned and untethered
robots. Created and designed
at Woods Hole Oceanographic
Institution, ABE is the first of its
kind, and still in the
development stages. ABE
stands for Autonomous
Benthic Explorer. It was
designed because scientists
have the need to monitor an
area over a long period of time,
and go very deep. ABE will be
programmed to move on its
own without a pilot (unlike the
submersibles Alvin or Jason) or
tethered to a ship, and perform
a set of tasks over several
months.
ABE has a ‘body’, muscles
(thrusters), nerves (cabling
power to operate the motor,
cameras, and sensors), and
brain (computer systems for
power, and determining where
to go and make
measurements). The data will
not be available until the
instrument is recovered.
Initially, ABE will only be able to
perform the tasks that it is preprogrammed to do, but as
technology advances that is
expected to change.
Ultimately, scientists hope to
use underwater acoustic data
transmission systems to allow
scientists anywhere in the world
to receive live video and data
from ABE, as well as control its
movement and sampling.
Buoys and Probes
Buoys and
probes are
useful
because they
can be left
for long
periods of time, and outfitted to
collect many different pieces of
data. Some of the data they
collect includes salinity, water
velocity, temperature, light, pH,
underwater geography, and
sound.
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
The size of the buoy varies
due to the instruments that it
carries, and also depending
on the length of time that the
buoy is to remain in the water.
The buoys are dropped in the
ocean using a large crane on
a research vessel, and left
unattended until the vessel
retrieves it. Some of them are
equipped with satellite
transmitters.
Sound Used in Ocean Research
There are four major categories
of sound exploration. The first
involves the use of receiving
devices called hydrophones.
Hydrophones listen to ambient
or background noises such as
those emitted by whales, fish or
submarines. The second is
SOund Navigation And
Ranging, abbreviated SONAR.
This involves sending and
receiving signals reflected from
objects (fish, submarines)
within the water or the seabed.
Using the time it takes the
signal to return to the receiver,
water depth and much more
can be calculated. Echosounding techniques are very
useful for depth determination,
and mapping the seafloor.
These instruments have
become very sophisticated and
can detect groups of very small
©PROJECT OCEANOGRAPHY
FALL 2000
zooplankton. There is really no
difference between
echolocation and SONAR,
except that echolocation is
much more informative than
SONAR. It allows much more
detail and description to be
interpreted, where SONAR
finds objects and the distance
they are away. Marine
mammals that use echolocation
could distinguish between a live
animal, or an object. Finally,
sidescan-imaging systems
produce the equivalent of aerial
photographs or radar images
using sound. The names of a
few of these systems are
GLORIA (Geological Long
Ranges Inclined Asdisc), and
TOBI (Towed Ocean Bottom
Instrument).
SOUNDS OF THE SEA
Future of Ocean Research
Ocean Research is big
business. It is important to
researchers, engineers,
politicians, mining, fisheries
and marketing business
people. As technology
advances, so does the
equipment used for ocean
research. More data is
available, better resolution is
achieved, and continuous
data collection is now possible
through satellite monitoring.
What is even more exciting is
that scientists can often forgo
the lengthy and expensive
research trips that have been
customary in the past!! The
study of the ocean is only
going to become more
complete and more accurate
as technology continues to
advance.
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
Activity 4-1. Phone a Friend
Alexander Graham Bell built the first telephone. Many years ago, it was
necessary to lay underwater cables across the ocean for people to call across
the ocean. Today, cables are not necessary, and the signals are bounced
through satellites as waves. Experiment with the following activity to understand
how sound travels.
Materials and Methods
Hammer
Nail
2-3 empty 540 mL cans
heavy string
a friend
Procedure:
1. Use a hammer and nail to punch a hole in the center of the bottom of
each can.
2. Cut a piece of string 7m (21feet) long. Push one end though each end
of the can, and tie the string so that the knot is inside the can.
3. With your friend, take the phone outside and hold the cans far enough
apart so that the string is stretched tightly.
4. Talk into the can while your friend holds the can to his/her ear.
5. Make the same phones with strings of other lengths and notice how
sound is different.
6. Now add a third person. Tie a string, with can attached to the middle of
the original string. How does this change the sound?
How it works
When you speak, the metal on the bottom of the can
vibrates. This causes the string to vibrate. The vibrations
travel through the string, and into your friend’s can.
A real phone has a metal disc that vibrates. This disc causes tiny
grains of carbon to vibrate. Electricity flows through them, and
passes through the telephone wires to the receiver at the other end.
A tiny magnet in the phone receiver changes the electric current into
sound vibrations that can be heard.
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
Activity 4-2. Play the Table Settings
Have you ever tapped your fingernail on a glass, drummed your
finger on a closed can of vegetables, or rubbed your finger across the
rim of your glass? Have you ever scraped your fingernails over the
chalkboard or a mirror??! This is called playing an idiophone. In
Greek, Idio- means self and phone means sound. An idiophone is
something that naturally makes sounds when it is rubbed, struck,
shaken, or scraped.
Materials:
Water
Several wine glasses
Procedure:
1. Fill the wine glasses with different amounts of
water.
2. Wet a fingertip, and rub it on the rim of each
glass until it ‘sings’.
How it works
Look at the water! It vibrates as the glass vibrates. The water in
the glass slows down the vibration. That is why the glass with the
most water makes the lowest sound.
Student Activity Sheet
Attached is a Student Activity Sheet that illustrates how a research
vessel is organized. Every inch of the vessel is utilized. Have the
students discuss how close the quarters are, and how different
research would be conducted on the ship. Examples of different
types of research would include cruises to study sediment samples,
fish ecology, conduct water quality testing, nutrient experiments,
deploying buoys and arrays, and remote sensing.
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
Unit 3. Lesson 4. Student Activity Sheet 4. How to Live on a Ship
This is the inside of a research vessel at
Woods Hole Oceanographic Institution
How would you like
to spend several months
on a ship this size?
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
Unit 2. Lesson 5. Sound Pollution in
the Ocean
Objectives: Upon completion of this unit, students will understand that noise pollution is
more than loud noises. They will also learn what causes hearing damage and
that animals, as well as humans, are subject to hearing loss.
Vocabulary words: litter, pollution, loudness-related hearing loss, blast trauma
What is Noise Pollution?
Litter on the side of the road,
junk floating in the water, and
smokes spewing into the
atmosphere from factory
smokestacks are obvious forms
of pollution. There are other
types of pollution that are not
as obvious. Noise pollution is
one form. What is noise
pollution? It is defined as
sounds, or noises, that are
loud, annoying and harmful to
the ear. Often, sound pollution
is thought to be a sound so
intense that it could shatter
glass, or crack plaster in rooms
or on buildings. That is not so.
It can come from sources such
as jet airplanes, constant
droning of traffic, motorcycles,
high-power equipment, or loud
music.
How is Noise Pollution Harmful?
Sound energy is transferred
through compressions and
rarefactions.
(Reference
lesson 1, if
necessary.)
If the
intensity is
very large, it can harm human
and animal ears, and do
damage to physical structures.
When sound reaches the
human ear, it causes structures
to vibrate. Intense vibrations
can rupture the eardrum, but
more often, loudness-related
hearing loss usually develops
over time. When sound enters
the ear, it is transferred to the
brain as a nerve impulse. Each
nerve is composed of tiny nerve
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
fibers, surrounded by special
fluid within the ear. When
intense sound is transferred (as
compressional waves) through
the fluid, the tiny nerve fibers
are destroyed, and hearing loss
occurs. Sounds in the
frequency range of 4,000 to
20,000 Hz cause most of the
damage to the nerve fibers.
Noise pollution sometimes
requires legal intervention
because it can be harmful. The
laws have been created
because loud sounds can
damage the ear, not only in
humans, but also in animals.
Hearing Loss in Humans and Marine
Mammals
Background noise in the ocean,
including the noise of ships and
other industrial activity, can
interfere with marine mammals’
use of sound for hunting,
navigating, and communicating.
This is called masking.
Noise trauma is another
impact that results in declined
hearing ability in marine
mammals. Sudden and long or
repeated exposure to high
frequency sounds can cause
permanent hearing loss.
Sudden onset of intense
sounds can also induce trauma.
One of these sounds would be
the sudden revving of a boat
engine from idle to full speed.
The motor makes a very sharp
and distinctive change in
sound.
©PROJECT OCEANOGRAPHY
FALL 2000
Another injury that marine
mammals suffer from is blast
trauma. This
results from a
single
exposure to a
sound that
has an
explosive
shock wave. The shock wave
has a compressive wave phase
carrying much energy through
the water quickly. The
pressure rises much higher
than normal for a few seconds,
and then drops quickly to levels
below normal. This is much
like the feeling that humans
have during the ascent and
descent of an airplane;
although it is much, much
faster. So fast, that it causes
damage to the ear of marine
mammals. The damage may or
may not be reparable.
SOUNDS OF THE SEA
Specifics of Hearing
The ability to hear is at its peak
at birth. From there, it
decreases with age. This is
called degenerative hearing
loss, or degeneration. Humans
are born with a hearing range
of 16-30,000 cycles per
second. The measurement of
cycles per second is also called
hertz. A cycle per second
refers to the number of times
per second that the mallet in
the ear touches the eardrum,
and transfers information. By
the age of twelve, that has
declined to approximately
20,000 cycles per second.
Grandparents at the age of 50
and older might only hear 4000
cycles per second.
In marine mammals, the ability
to hear high frequencies is the
first hearing loss to occur.
Remember, many marine
mammals hear and detect
sounds that are much higher
and lower than the human ear
can detect. Loss of high
frequency hearing in marine
mammals could result in the
animal losing its locating ability,
and its ability to detect food or
predators.
It is commonly thought that all animals suffer from degenerative
hearing loss. The ability to hear is at its peak at birth. From there, it
decreases with age. Outside forces act strongly on hearing loss.
Some forms of these include:
Drum punctures (perhaps from pressure).
Ringing resulting from fever, tumors, and circulation
changes.
Infection (usually middle ear in the Eustachian Tube)
Bone overgrowth
Loudness
All of these forms of hearing loss can be applied to marine mammals
and humans. Unfortunately, marine mammals have a few more
problems to contend with.
β Underwater shock waves
✸ Underwater explosions (perhaps missile testing, or from mining)
And last but not least:
Motorboats of all kinds.
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
Activity 5-1. How Loud is Too Loud?
Use the diagram found in the Student Activity Sheet for this unit
to answer the following questions.
How Loud is :
1.
2.
3.
4.
5.
6.
7.
8.
Chain Saw
Breathing
Just audible sound
Conversation in a
restaurant
Racetrack
Airport
Airstrip with planes taking
off
Raking leaves
_________
__________
__________
__________
__________
__________
__________
__________
Now, rearrange the sounds in order of increasing loudness.
Estimate and discuss the loudness of the following:
A. Rustling of a newspaper. (Remember average home sounds =40
dB and rustle of leaves = 20 dB)
B. Air drill breaking cement (Remember that a Power Mower = 100
dB and a Chain Saw is 115 dB.)
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
Activity 5-2. Making Sounds.
Sounds can be heard over long and short distances. Why do some
sounds get higher as they get closer? Why do sounds like a siren
sound louder as they get closer, and not as loud the further you get
from them?
This is because of a phenomenon called the Doppler Effect. For
example, an ambulance is moving quickly along a road near your
B
A
house, blaring its horn. The pitch of the horn sounds higher, as it is
coming near, than it would if it were standing still. This is because
the crests of the waves expand in larger circles from the spot where
they started. By the time crest B left the truck, the truck had moved
forward causing crest B to be closer to crest A in front of the truck.
The sound that is left behind the ambulance has crests that are
further apart, and therefore, the volume of the sound reaches our
ears as less.
Materials:
• Rubber stopper
• Tuning fork
• two students
Procedure A:
1. Ask yourself this question, what is the relationship between
loudness and the distance between the ear and the source of the
sound?
2. Hit the rubber stopper lightly. Listen to the sound.
3. Hit the rubber stopper again, strongly.
4. Observe and listen to the sound.
5. Discuss the difference in sound.
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
HOW IT WORKS.
After the tuning fork was hit lightly on the rubber stopper, the
amplitude of sound emitted was small. When it was hit on the
rubber stopper more strongly, the amplitude increased.
Procedure B. Why does sound decrease in loudness with distance?
1.
2.
3.
4.
Have one student stand very close to the tuning fork.
Hit the fork on the stopper.
Have the student move further away and hit the stopper again.
Have them describe their ‘listening’ responses.
HOW IT WORKS.
When the student is close to the tuning fork, the distance the sound
must travel is short. When the student moves further away from the
experiment, the volume of air that the sound wave must travel through is a
greater distance. Thus, there is more air to attenuate the sound, and perhaps
the student is intercepting a smaller part of the sound wave. Thus, not
receiving it in its entirety, and getting only part of the sound.
air
location 1
location 2
Sound travels in all directions. Sound waves spread over volume, not area.
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
Student Information Sheet 5. How Loud is
What You Hear?
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
Unit 2. Lesson 6. Recording
Sounds From Wild Marine Mammals
Lesson Objectives:
• Students will gain an understanding of the technology used by researchers to study
underwater sound.
• Students might want to explore the internet books to learn more about acoustic
oceanography.
Vocabulary Words: hydrophone, SOSUS
There are good reasons for
improving our understanding of
the way in which marine
mammals communicate and
navigate. Biologists and
researchers are accomplishing
this task using recordings of
animals in the wild and in
aquaria around the world.
Collecting sounds from
underwater is a huge task, and
many techniques are being
used (hydrophones, arrays and
more). Computer models and
further mammalian studies are
being used to interpret the
meaning of the sounds
collected.
Problems Researchers Face
Recording sounds from marine mammals is not an easy task. There
are four problems that all researchers face in doing so:
Determine which animals make sound
How to make accurate recordings
Finding the animals
How to make a quality recording of a moving animal
The marine
environment
provides a difficult
environment
because it is wet!
Instruments must be
able to withstand the water and
be leak proof. In addition, the
instruments must be able to
©PROJECT OCEANOGRAPHY
FALL 2000
withstand the effects of salinity,
temperature, pressure, and
motion. At the same time, they
must be very sensitive and able
to clearly record both high and
low frequencies.
SOUNDS OF THE SEA
Tools Developed to Solve Recording
Problems
The recording of marine
mammal sounds occurred
purely by accident. During
World War 1 (1914-1918), Sir
William Henry Bragg developed
the hydrophone. The
hydrophone is an instrument
that was developed to ‘hear’
enemy submarines.
Additionally, the hydrophone
detected marine mammal
sounds underwater. This was a
very pleasant surprise to
researchers around the world.
Suddenly, there was a way to
learn more about the sounds
generated by marine mammals.
station(s). These stations exist
worldwide. Over the years,
many more arrays were set
down. As the military continued
to use the hydrophone arrays
for military purposes and
submarine detection, the data
collected from marine
mammals sounds provided
excellent research materials for
scientists all over the world.
The SOund SUrveillance
System became known as
SOSUS. SOSUS made it
possible to detect, and
differentiate whale calls and
help track migrating whales.
The work of Sir William
Henry Bragg continued
to be of great interest
to the military, as well
as the research
community. The
military made acoustic
networks of passive
hydrophone detector
arrays, and laid them
in the Atlantic and
Pacific Oceans.
Hydrophone arrays are
located at intervals of 5
to 15 miles along a
linking cable
connected to shore
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
In addition to hydrophone
arrays (SOSUS, and individual
arrays) scientists use towed
arrays behind a ship to record
animal sounds. This can be
done using two to hundreds of
sensors attached to a towline
that is trailed behind a slowly
moving ship. This is a useful
method, because it can be
used to track a moving animal.
The drawback of this method is
ship noise is also recorded.
Technology has allowed
scientists to also track animals
by attaching sensors to the
animal. Having the ability to
attach a sensor without injuring
the animal allows the normal,
wild behavior of the animal to
be recorded. Information
obtained from these recordings
includes how often and how
deep an animal dives, sounds
individual animals make, and
location of migration paths.
The animals usually wear the
small sensor or tag either on
their backs or fins. The
information is either relayed
from the sensor to a satellite
and back to the shore or ship,
or it is recorded on the tag that
is later recovered to retrieve the
data. There are two difficulties
with this method of tracking and
listening to animals. The first is
that the sensors are expensive
and often lost. The second is
that the sensors often are
battery powered and have a
limited lifetime.
A Deeper Look
There is a lot of information about Marine Mammal Acoustics on the
internet. Some of the sites contain sounds that have been recorded
from marine mammals, while others contain information. A few
interesting websites include:
• http://newport.pmel.noaa.gov/whales/s
ounds.html
• http://www.pinger.ios.bc.ca
• http://oceanographer.navy.mil/content.
html
Also, do a web search for SOSUS and you will come up with many
different research topics and results.
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
Activity 6-1. Listen to the Sound!
When scientists record underwater sound, they might pick up the
snapping of crab claws, bubbles popping, speed boats, marine
mammals, and children swimming. Try the next activity to see what
kinds of sounds you can listen to that you do not hear easily.
MATERIALS:
• 12 inches of plastic aquarium tubing
• 2 small funnels (miniatures work the best)
• balloon
• rubberband
• scissors
• a friend
Procedure:
1. Fit the ends of the funnels into the tubing.
2. Cut the top 1/3 to ½ of the balloon. Stretch this over one large end
of one funnel until it is very taut.
3. Attach with a rubber band, if necessary.
4. In a quiet room, hold the funnel end with the balloon flat against
your chest to the left of the center.
5. Hold the funnel end without the balloon to your ear.
6. Listen to your heartbeat.
7. If you want, count the number of beats for 15 seconds, and then
multiply by 4. This is how fast your heart beats in one minute.
Variation
Listen to your belly. Perhaps you just ate a meal and your stomach is
digesting the food.
Listen to other people’s heartbeats. People of different age and
physical state will have different heartbeats.
Have your friend blindfold you and take you to different things to
listen to. Tell your friend what you are hearing. It may take some
practice. Remember, this is how scientists discover new marine
mammal sounds. Some things to listen to might include:
• A fish tank.
• The wall of an adjoining room.
• A running refrigerator.
• A desk top with someone tapping his or her fingers on it.
• The floor as people go down a flight of stairs nearby.
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
Student Information Sheet 6. Fun and
Interesting Facts about Sounds
White beluga whales are nicknamed the “sea canaries” because they
cheep and chirp like birds. They can also moo like cows, chime like
bells, or press their lips together with a loud smack.
Whales and dolphins use sound to ‘see’. As they swim they make
clicking noises, which travel through the water. When the clicks hit
something solid, an echo bounces back – just like a ball bouncing off a
wall. The echo tells the animal what lies ahead.
The military helped scientists to make progress in studying marine
mammal sounds through the use of their hydrophone array called
SOSUS.
Since the famous composer Beethoven was almost deaf, he used his
teeth to compose music. To help him hear while he was writing, he
would hold one end of a stick between his teeth and put the other end
against the piano strings. When he played a note, the sound traveled
through the stick, through his teeth, and skull bones directly to his inner
ear.
Some toy guns emit sounds of 170 decibels! That is in the range for
permanent ear damage!
If you play your portable cassette player with the earphones on at over
more than ½ its possible volume, you are damaging your inner ear.
Snakes “hear” by setting their heads on the ground. A sensitive bone in
the head picks up vibrations. The vibrations travel to the snake’s brain
via a cochlea, similar to the one inside the human ear. Others hear
sounds through special organs. Crickets ‘hear’ through membrane-like
eardrums on their thighs, spiders pick up vibrations through leg hairs,
tarantulas feel vibrations on the soles of their feet, and fish use lateral
lines and hearing sacs in their heads.
Why do astronauts use a radio to talk to each other in space? Sound
waves cannot travel in space because there are no air molecules or
medium to carry them. Radio waves can travel where there are no
molecules.
Sound travels 4 times as fast through water as it does through air.
Marine mammals are not the only animals that communicate with
sounds that humans cannot hear. The male elephant can hear the love
call of a female cow many kilometers away. Humans cannot hear these
sounds because they are higher or lower than the frequency heard by
the human ear.
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
Vocabulary for Unit 2
acoustics: the study of sound
amplitude: in a wave, the distance from the resting position to either the crest or
the trough.
ARGOS: a satellite system used solely for environmental monitoring. It monitors
approximately 3,000 buoys, moorings, and floating arrays worldwide.
autonomous: independent
blast trauma: the reaction or effect on an organism to an explosion with a strong
shock wave quickly carrying much energy through the water, followed by a
rarefaction wave with pressure below the ambient level
buoy: an anchored float used as a marker or as a mooring
Carnivora: class of meat or flesh eating animals
Cetacea: an order of aquatic animals that chiefly contains marine mammals,
including the whales and dolphins
compressional wave: a wave that vibrates in the same direction in which the
wave is traveling
cognition: the act or process of knowing, perception
crest: in waves, the highest point of a wave
CTD: an instrument commonly used to measure the conductivity, temperature
and depth of the ocean
echolocation: a method of locating objects by determining the time for an echo
to return and the direction from which it returns, as by radar or sonar.
frequency: the number of waves that pass a point during one second, expressed
as hertz
hertz: the unit of measure for frequency, abbreviated Hz and the units are 1/sec
hydrophone: a device for detecting sounds transmitted through water, as for
locating submarines or measuring the flow of water through a pipe
idiophone: something that naturally makes sounds when it is rubbed, struck,
shaken or scraped
larynx: a muscular and cartilaginous structure at the upper part of the trachea, in
which the vocal cords are located
litter: rubbish, objects strewn or scattered about
loudness related hearing loss: loss of hearing as a result of noise being
constant, or too loud for the human ear to handle over a period of time.
Also, degeneration of hearing as a result of age
mammal: a warm blooded vertebrate of the class Mammalia, characterized by a
covering of hair on some or most of the body, having a four-chambered
heart, bearing live young and nourishing the newborn with milk from
maternal mammary glands.
masking: obscuring or blocking a sensory process by another sensory process
maxillary: one of a pair of bones constituting the upper jaw
medium : a material (liquid, gas, or solid) through which a mechanical wave can
transfer energy
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
navigation: to move on or through the water on a due or known course with
knowledge of the items and materials ahead
neural impulses: messages relayed to the brain in the form of electrical energy
that causes the brain to make a physical response
nasal system: the sinus cavity and areas surrounding the nose
noise pollution: sound that is loud annoying, or harmful to the ear
noise trauma: a result of a sudden or prolonged noise of broad bandwidth
usually resulting in permanent hearing loss
oily melon: the structure at the front of the head of a dolphin. When clicks or
other sounds are emitted, sounds are compressed through this area of the
head for better transmission through the water. It has about the same
density as seawater
order: a kind, person or animal that is separated from others by distinctive
characteristics
pelagic: of or pertaining to the open ocean or seas
pharynx: the portion of the alimentary canal that connects the mouth and nasal
passage with the larynx
phonating: producing a sound, chirp or whistle
pinnae: the visible portions of the ear that project from the head
pod: a small herd of seals, dolphins, or whales
pollution: items and materials that are left by the wayside and out of place;
garbage, trash in the environment
rarefaction: in compressional waves, the less dense area of the wave
resonator: an instrument for detecting the presence of a particular frequency by
means of sound or reverberation
rest position: the level of the medium when the wave is not in motion.
rostrum: a beaklike anatomical process or extension of the head
satellite: a device launched into orbit around the earth, another planet, the sun,
or a moon
sensory cells: a physiological structure used for receiving or conveying an
external stimulus
Sirenia: a classification for specialized aquatic herbivorous mammals, including
the manatee and the dugong
sinusoidal: a curve that has equal distances to straight parallels spaced at
regular intervals
social structure: of or pertaining to life and how the animals are organized
within family structure
sound: a noise, a song, a vocal utterance, or the like
SONAR: an acronym for SOund Navigation And Ranging, a method for detecting
and locating objects submerged in water by echolocation
SOSUS: a SOund SUrveillance System used by the United States military that
became useful to researchers because it recorded marine mammal
sounds
tether: a rope, chain, or the like, by which an instrument is fastened to a fixed
object to limit its range of movement
topography: detailed mapping or charting of the features of an area or district
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
transverse waves: waves that vibrate at right angles to the direction the wave is
traveling
trough: in waves, the lowest point of the wave
vocal cords: membranes stretched across the larynx that produce sound or
voice as they are made to vibrate by the passage of air from the lungs.
vocalization: to make into a sound
wavelength: the distance between a point on one wave and the identical point
on the next wave; for example, the distance between two crests or two
troughs.
©PROJECT OCEANOGRAPHY
FALL 2000
SOUNDS OF THE SEA
References
Brekhovskikh, L.M. and Yu P. Lysanov. 1991. Fundamentals of Ocean
Acoustics. Springer-Verlag, New York, New York. Pp. 270
Caruthers, Jerald. 1977. Fundamentals of Marine Acoustics. Elsevier Scientific
Publishing Company. pp.153
Kaner, Etta. 1991. Sound Science. Addison Wesly Publishing Company.
Reading, MA. pp.96
Ortega, C. and Woodward, B. “New Argos Capabilities for Global Ocean
Monitoring.” Sea Technology. Vol. 4, number 5. pp. 59-66.
Reynolds, J.E. and S.A. Rommel. 1999. Biology of Marine Mammals.
Smithsonian Institution Press. Washington, DC. pp. 578.
Twiss, J.R. and R.R. Reeves. 1999. Conservation and Management of Marine
Mammals. Smithsonian Institution Press. Washington, D.C. pp. 471.
Vehicles and Vessels of the Woods Hole Oceanographic Institution. Woods Hole
Bulletin, 1999. Information Office 1-580-457-2000 x2252
Fun websites for Teachers to visit:
Amateur Science
The Science Learning Network
©PROJECT OCEANOGRAPHY
FALL 2000
www.amasci.com/
www.sln.org