17.4 Sound and Hearing

Properties of sound waves.

Properties	Definition	Depends on
Speed	the ratio of the distance an object moves to the amount of time the object moves	density of medium and how elastic the medium is
Frequency and pitch	Pitch- frequency of sound as you perceive it Frequency- the number of complete cycles per unit time for periodic motion	how fast the source of sound wave is vibrating
Intensity and loudness	Intensity- rate at which waves energy flows through a given area Loudness- physical response to intensity of sound	sound intensity and waves amplitude distance from sound source

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There is a difference in pitch because there is a different length of tubing

Uses

Ultrasound

Used in a variety of applications (Sonar, ultrasound imaging)
Sonar- determining distance to an object underwater
A frequency higher then most people can hear

Hearing with Ears

Three main regions of the ear
Outer- gathers and focuses sound for middle ear
Middle- receives and amplifies vibrations
Inner- uses nerve endings to sense vibrations and send signals to the brain

Music

Resonance- response of a standing wave to another wave of the same frequency
Can vary in pitch by frequency of standing waves
changes by the length of tubing or the length/thickness of strings

Doppler Effect

change in sound frequency caused by motion of the sound source
discovered by Christian Doppler
as a source of sound approaches higher frequency when it moves away frequency lowers

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