PSY 2364
Animal Communication
Honeybees
• Diploid animals (e.g. humans)
– 2 sets of chromosomes, one from each parent;
siblings share 50% of their genes
• Haplodiploid animals (e.g. honeybees)
Honeybee
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Apiidae
Genus: Apis
Species: mellifera
Honeybees
• Haplodiploid animals (e.g. honeybees)
– Males (drones) develop from unfertilized eggs and
have only one set of chromosomes (haploid)
– Female (queen) has two sets (diploid). One set is
passed on to her offspring. So queen and worker
bees/drones share 50% of their genes.
http://plantphys.info/Plants_Human/bees/bees.html
Honeybees
• Haplodiploid animals (e.g. honeybees)
– But all the workers (sisters) in the hive receive the
same set of genes from the male (50% shared) plus
one of two sets from the female (50% of 50% =
25%) for a total of 75% shared genes.
– Implications for social behavior?
Properties of sound
• Sound has three basic dimensions:
– Frequency (pitch)
– Amplitude or Intensity (loudness)
– Time (length)
1
Properties of sound
• amplitude:
– displacement magnitude of sound pressure wave
• intensity:
Waveform
• The waveform of a sound is a representation of
sound pressure (amplitude or displacement) versus
time.
Sine wave
Amplitude
– amount of sound energy per unit area
• frequency:
– number of times per second the pattern repeats
0
Time
Spectrum
Phase
• Two sounds can have the same amplitude and
frequency but differ in phase (onset position).
Cosine wave
Amplitude
Amplitude
Sine wave
0
0
Time
• The spectrum of a sound is a representation based
on a mathematical analysis of the waveform.
• Applying a theorem developed by Fourier, it
allows any sound to be decomposed into a set of
sine waves. Combining these sine waves will
reproduce the original sound.
Time
Spectrum
• The amplitude spectrum of a sound is a
representation of amplitude by frequency.
Intensity
Sine wave
Properties of sound
• Sine wave
–
–
–
–
–
Simplest sound type
Varies in a sinusoidal pattern over time
Period – 1 repetition (cycle/second, or Hz)
Amplitude – displacement of pressure wave
Phase – relative position; 360 degrees per cycle
Frequency
2
Properties of sound
Properties of sound
• Complex sounds
Intensity
• Periodic (tonal, repeating pattern in the waveform)
• Aperiodic (noise, with no repeating pattern)
Frequency
Cicadas (Order Hemiptera)
Complex wave (periodic)
Intensity
Sine wave
– Most sounds in nature
– e.g., human voices, bird and insect songs, frog
calls
– Complex sound types
Frequency
Dog-day Cicada
Tibicen resh
Periodical Cicada
Periodical (17-year) Cicada
(Magicicada septendecim)
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Uniramia
Class: Insecta
Order: Homoptera
Family: Cicadidae
Genus: Magicicada
Species: septendecim
http://animaldiversity.ummz.umich.edu/
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Periodical (17-year) Cicada
(Magicicada septendecim)
Cicadas (Order Homoptera)
• Medium to large insects with two pairs of
membranous wings, prominent compound
eyes, and three simple eyes (ocelli).
• Many produce loud sounds by vibrating
membranes (tymbals) near base of abdomen
• rhythmical ticks, buzzes, whines, or musical
sounds
• Congregational and courtship “songs”
Cicada sound production
Cicada sound production
Tymbal
• Most complex insect sound-producing
mechanism known
• Circular membrane surrounded by heavy
rings on cicada’s abdomen
• Contraction of tymbal muscle causes tymbal
to spring back, producing loud click or pulse
(120-480 per second); amplified by
resonating cavity in the abdomen
Tymbal
• Loudest known insect sound: up to 100
decibels at close range
• Most likely females detect and prefer males
with the loudest “songs”
Cicada tymbal
Cicada sound production
•
•
•
•
•
Phonotaxis – orientation toward sound
Song choruses
Synchrony or alternation
“Domino effect” (first song triggers others)
“Last word effect” (competition for last song)
Nahirney et al. FASEB 20 (12): 2017. (2006)
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Cicadas (Order Homoptera)
Eastern Cicada Killer
(Sphecius speciosus)
Examples of cicada songs
Stridulation
Fire ant stridulation sounds
Stridulation sounds:
3 strokes of the file.
Expanded view of 4 pulses:
Resonant oscillations
• Alarm signal generated by black fire ants
when a microphone probe is inserted into
their mound.
• Sounds of ants attacking a caterpillar with
stridulation sound from a single ant.
Source: Fletcher, N.H. (2007). Animal Bioacoustics. In Springer Handbook of Acoustics, edited by T.D. Rossing.
Stridulation in birds
• Manakins (Pipridae) are
polygynous neotropical birds
that use wing sounds to attract a
mate.
• During the mating season males
gather in display areas where
they compete with visual and
acoustic displays to attract
females.
• Role of sexual selection
(Darwin)
Red-capped Manakin
Stridulation in birds
Courting Bird Sings with Stridulating Wing Feathers
Kimberly S. Bostwick and Richard O. Prum
Science 309: 736 (2005).
www.sciencemag.org/cgi/content/full/309/5735/736/
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Stridulation in birds
Stridulation in birds
plectrum
• Specialized
adaptations of wings
for sound production
• Secondary wing
feathers are enlarged
and hollow with
regular, raised ridges;
neighboring feather
tapers abruptly to a
thin, stiff, blade.
plectrum
file
file
www.sciencemag.org/cgi/content/full/309/5735/736/
Primate vocal tract
• Tick–Tick–Ting sound:
fundamental frequencies
of 1590 and 1490 Hz with
harmonics at integer
multiples.
• Feather oscillations =
106/second
• Frequency multiplier:
106 x 14 ≈ 1490 Hz
The evolution of speech:
a comparative review
W. Tecumseh Fitch
Trends in Cognitive Sciences 4(7) July 2000
www.sciencemag.org/cgi/content/full/309/5735/736/
Human vocal tract
orangutans
air sac
tongue body
orangutan
chimpanzee
human
larynx
From Fitch, W.T. (2000). Trends in Cognitive Sciences
Specialized vocal resonators
Human vocal tract
Howler Monkey (Alouatta)
Gibbon (Hylobates)
Larynx
6
Respiratory structures
Vocal fold oscillation
• One-mass model
Larynx
• Main source of sound
production by mammals
• Controls airflow during
breathing and sound
production
– Air flow through the
glottis during the closing
phase travels at the
same speed because of
inertia, producing
lowered air pressure
above the glottis.
Source: http://www.ncvs.org/ncvs/tutorials/voiceprod/tutorial/model.html
Source-Filter Theory
Speech production
• Source: during normal (voiced) speech the
vocal folds vibrate at a frequency that
depends on their length and mass as well as
the amount of tension in the muscles that
control them.
• Filter: the vocal tract is a complex resonant
filter system that amplifies certain frequencies
and attenuates others.
From Fitch, W.T. (2000). Trends in Cognitive Sciences
Speech terminology…


Fundamental frequency (F0): lowest
frequency component in voiced speech
sounds, linked to vocal fold vibration.
Formants: resonances of the vocal tract.
Amplitude
Audio demo: the source signal
• Source signal for an adult male voice
• Source signal for an adult female voice
• Source signal for a 10-year child
Formant
F0
Frequency
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Helium speech
Helium speech
• Inhaling helium during speech changes the
frequencies of the vocal tract resonances but
keeps the pitch the same. Why? Because
sound travels faster in a helium mixture than
in air. The vocal tract resonances are shifted
up, but the vocal folds vibrate at the same rate
and the voice pitch is relatively unaffected.
•
•
•
•
Ordinary Speech
Helium Speech
Voice pitch in Air
Voice pitch in Helium
Helium speech UNSW Resources - Physics in Speech
http://phys.unsw.edu.au/phys_about/PHYSICS!/SPEECH_HELIUM/speech.html
Size variation in speech
Fundamental Frequency
Adults’
voices
Children’s
voices
Formant Frequencies
Anuran vocal communication
Bullfrog (Rana catesbeiana)
3
80
dB
70
60
Frequency
• Similar to mammals, anurans (frogs and
toads) produce sounds by forcing air
through a narrow opening (glottis).
• They also have a second pair of membranes,
upstream from the glottis, that vibrate at a
higher frequency.
Examples: vocal sounds
2
50
40
30
1
20
10
0
0
1000
2000
Time
3000ms
Sound spectrogram
8
Anuran sound production
Examples: vocal sounds
Bullfrog (Rana catesbeiana)
Anuran
vocal cords
Glottis
Frequency
Sound spectrogram
Arytenoid cartillage
Time
Anuran vocal communication
Anuran vocal communication
• Each species of frog produces
distinctive (species-specific) calls that
play an important role in mate choice.
• Many species form groups called leks,
where males call simultaneously to
attract females to breeding sites.
• Males compete with each other by
calling and sometimes by physical
aggression.
• Sexually receptive females locate and
choose a single male as mate based on
properties of the call.
Anuran vocal communication
Syrinx
• Some frogs have an inflatable throat sac that
selectively amplifies certain frequencies in
the source signal and also serves as a visual
signal.
• Found in birds
• Located at the base of the
trachea where the two
bronchial tubes converge
• Contains two separate
oscillating membranes that
allow generation of two
different sound sources
(modulated frequencies)
simultaneously
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Syrinx
Syrinx
• Sound production is controlled separately
for each side of the syrinx by several
muscles that are innervated by motor
neurons in the hypoglossal nerve coming
from the same side of the brain. The right
side of the syrinx seems to produce a higher
range of frequencies than the left side.
• The Cardinal video shows how birds can
switch rapidly and seamlessly from one side
of the syrinx to the other. Upward sweeps
start on the left and switch to the right;
downward sweeps reverse this pattern.
• Some birds can produce harmonically
unrelated sounds simultaneously from the
two sides of the syrinx (catbirds, thrashers).
Syrinx
Bird songs
• Bird songs often include frequencymodulated notes that sweep through a wide
range of frequencies
• In cardinals, frequencies below 3500 Hz are
generated using the left side of the syrinx;
higher frequencies use the right side.
http://www.indiana.edu/~songbird/multi/songproduction_index.html
Frequency (kHz)
Zebra Finch song
Sound spectrogram
Song development in birds
• Chaffinch (Fringilla coelebs)
Time (sec)
10
Examples: vocal sounds
Examples: bird vocal sounds
Ferruginous Pygmy Owl
Woodhouse’s Toad (Bufo woodhouseii)
Pileated Woodpecker
Brazilian Free-tailed Bats
(Tadarida braziliensis)
Rufous Mourner
Three-wattled Bellbird
Javelina
Winter Wren
Coyote
Song Sparrow
Whale songs
Non-vocal sounds
Rattlesnake (Crotalus)
Fruit fly (Drysophila melanogaster)
“wing song”
Large body size allows whales and
elephants to produce high intensity, low
frequency sounds. Both properties increase
the range (distance) for communicating with
conspecifics.
8x normal speed
Mosquito (Aedes) wing sounds
Functions of sound communication
1.
2.
3.
4.
5.
To bring animals together
Identification (species, group, individuals)
Synchronization of physiological states
Monitoring the environment
Maintenance of special relationships
Ecological constraints
1.
2.
3.
4.
5.
energy costs
overcoming environmental obstacles
locatability of the source
rapid fading
range of physical complexity
11
Acoustic properties of the medium
Communication by sound
1. Sound production
•
•
Production and modulation of acoustical energy
Coupling of vibrations to the medium
Medium
Speed of sound
(cm/sec)
Density of medium
(g/cm3)
Acoustic
Impedance (rayls)
Air
0.3 x 105
1 x 10-3
0.0003 x 105
Water
1.5 x 105
1
1.5 x 105
Rock
2-5 x 105
2-3
4-5 x 105
2. Transmission through medium
•
•
Impedance matching
Sources of distortion
3. Sound reception
•
•
Coupling of vibrations to sound receptors
Mechanical-to-neural transduction
Source: Bradbury and Vehrencamp (1998). Principles of Animal Communication
Ecological constraints on acoustical
communication systems
1.
2.
3.
4.
5.
energy costs
overcoming environmental obstacles
locatability of the source
rapid fading
range of physical complexity
Production and coupling of vibrations
• Stridulation – sharp blade (plectrum) is rubbed
against a row of small teeth (file)
• Dipole – sound source that vibrates back and forth
– Acoustical short-circuit: cancellation of waves makes it
difficult to produce loud sounds
– Frequency multiplier (multiple teeth)
– Sound baffle (tree crickets)
– Use short-range signals (most insects)
Exploiting resonance
Bornean tree-hole frogs
(Metaphrynella sundana)
seek out tree trunks partly
filled with water. They tune
their vocalizations to the
resonant frequencies of the
cavity.
Factors affecting acoustic
signal transmission
•
Absorption - loss of energy due to contact
with medium, which may convert signal's
energy into another form (e.g. heat)
Source: Lardner and Lakim, (2002).
Nature 420: p. 475.
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Factors affecting acoustic
signal transmission
•
Attenuation - decline in signal intensity
due to absorption, scattering, distance
from source; particularly high frequencies
Factors affecting acoustic
signal transmission
• Geometric spreading - signals radiate in
several directions from the source; not
perfectly directional; result = energy loss
Factors affecting acoustic
signal transmission
• Reflection - signal bounces back in the
direction of the emitting structure as a result
of striking a reflective medium
Factors affecting acoustic
signal transmission
•
Diffraction - redirection of the signal
because of contact with an absorbing or
reflecting medium
Factors affecting acoustic
signal transmission
• Interference - signals reflected from the
substrate later interact with the originally
transmitted signal
Factors affecting acoustic
signal transmission
• Refraction - signal direction/speed is
altered/perturbed by medium or climatic
changes like temperature gradients
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Factors affecting acoustic
signal transmission
• Reverberation - multiple scattering events
produce a time delay in the arrival of the
signal, perceived as an echo; blurring
Obstacles and sound transmission
• Vegetation (tree trunks, leaves) and other
obstacles can obstruct sound transmission.
• Echoes are produced when sounds are reflected
from an obstacle and follow an indirect path to
the ear of the receiver.
Factors affecting acoustic
signal transmission
• Scattering - signal contacts an obstruction
and undergoes a complex multidirectional
change in the transmission direction
Obstacles and sound transmission
• Low frequency sounds have longer
wavelengths than high frequency sounds
and can bend around obstacles.
Sound wave reflecting off a wall
Source: http://myweb.dal.ca/mkiefte/
Sound power and body size
• Total sound power depends on the size of
the animal (animals with small body mass
tend to produce sounds with low acoustic
power).
• Some exceptions to this rule: cicadas
Source: http://myweb.dal.ca/mkiefte/
Modes of sound production
• Monopole - sound alternately contracts and
expands in concentric circles around source.
– alternating compression and rarefaction
used by some fish (pulsating air sac)
• Dipole - sound source that vibrates back
and forth
– E.g. stridulation in crickets
– Efficiency of sound transmission?
14
Monopole
Dipole
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