Chapter 2: Sound
Name_____________________
Section 1
Sound Waves
*Sound is a disturbance that travels through a
_medium___ as a longitudinal wave.
*Sound waves are caused by ___vibrations______.
*Sound waves carry ____energy______ through a
_____medium________ without the particles of the medium moving
along.
Interactions of Sound Waves
*Sound waves can ___reflect___ off of objects they hit.
The reflection of sound is called an ____echo_____.
*Sound wave can bend around objects or travels through openings.
This is called _______diffraction_________.
*When sound waves meet they may cause constructive or destructive
_____interference______.
Speed of Sound
*The speed of sound at room temperature is _____343______m/s.
*Speed depends on __3___ factors.
1. __Elasticity__ is the ability of a material to
bounce back after being disturbed. Materials that are
__more__ elastic transmit sound faster. _solids__ are generally
more elastic than liquids or gases.
2.__Density__ is how much matter, or
mass there is in a given amount of space. The denser the
material the ____slower____ the speed.
3. ___Temperature____- sound travels faster when
temp. is _higher_____ because particles move quickly.
*Breaking the sound barrier means to __fly faster than the speed of
sound ______________.
Section 2 : Properties of Sound
Loudness
*Loudness describes your perception of the _energy__ of a
sound.
*Loudness depends on two factors: amount of __energy___
to make the sound and the ___distance__ you are
from the source.
*Higher __energy___ results in louder sounds.
*__intensity___ is the amount of energy that a
sound wave carries.
*Loudness is measured in __decibels___(dB).
Examples:
Whisper ___15-20______dB
Classroom __40-50_____dB
Normal Conversation _____40-50_____dB
Loud music ____90-100________dB
(Greater than 100db can damage hearing)
Jackhammer ____120____________dB
(causes pain)
Space Shuttle Launch ___200________dB
(immediate irreversible hearing loss)
Pitch
*Pitch is the __highness__ or lowness of sound. Pitch
depends on the ___frequency____ of the sound wave.
*High frequency equals High ___pitch______.
*Frequency is measured in ____hertz__(Hz).
*Humans hear frequencies from __20___ to __20,000___Hz.
*__ultrasound___ are frequencies above our hearing
range. ___infrasound_____ are frequencies below our
hearing range.
The Doppler Effect
*The ___Doppler___ effect is a change in frequency of a
wave as its source moves in relation to an observer.
Example: ____racetrack, siren on police, plane passing by______
Section 3
Sound Quality
*Music is a set of notes that combine in ___patterns___ that
are pleasing.
*Noise has no pleasing ___patterns___.
*Every object has its own ___natural_ frequency.
*Resonance occurs when an _____object_ causes another
object to vibrate at a natural frequency.
Acoustics
*Acoustics is a study of how sounds _interact____ with
each other in an ___environment_____.