PROPERTIES OF SOUND CHAPTER 2, SECTION 2

Loudness describes your PERCEPTION of sound. The loudness of sound depends on 2 factors: The amount of _ENERGY_ it takes to make the sound The _DISTANCE__ from the source of the sound.

Energy of a Sound Source The greater the _AMPLITUDE_ of a wave, the more _ENERGY_ the wave has The larger the _AMPLITUDE_ of the sound wave, The _MORE_ energy it has and the _LOUDER_ the sound.

Things with a large amplitude: Rocket ship Jet engine Rock concert Things with a small amplitude: Whisper Soft rain Slow moving river

_LOUDNESS_ increases the closer you are to a sound source. The closer the sound wave is to its _SOURCE_, the more _ENERGY_ it has in a given area. Mosquitone sounds http://www.mosquitone.net/what-is-the-mosquitone.html

If you are close to a speaker it is louder than if you are far way. As you move away from a sound source, _LOUDNESS_ decreases because intensity _DECREASES_. Think about it: If you are close to a speaker it is louder than if you are far way. Mosquitone sounds http://www.mosquitone.net/what-is-the-mosquitone.html

Measuring Loudness The unit to measure loudness is called the ___DECIBELS___. It is abbreviated as dB. Mosquitone sounds http://www.mosquitone.net/what-is-the-mosquitone.html

PITCH The pitch of a sound is a description of how _HIGH_ or _LOW_ the sound seems. The pitch of a sound that you hear depends on the __FREQUENCY_ of the sound wave.

PITCH A high frequency wave means a high pitch. A low frequency wave means a low pitch.

PITCH AND FREQUENCY Sound waves with frequencies above the normal human range of hearing are called __ULTRASOUND__.

PITCH AND FREQUENCY Sound waves with frequencies below the human range of hearing are called __INFRASOUND__.

CHANGING PITCH Changing Pitch To speak air _VIBRATES__ your vocal cords. Stretched vocal cords produce _HIGHER_ frequency. Relaxed vocal cords produce __LOWER__ pitch Brain Pop = Voice

THE DOPPLER EFFECT The Doppler Effect The change in frequency of a wave as its source moves in relation to a observer is called the _DOPPLER EFFECT__. The change in frequency is heard as a change in __PITCH__. The Big Bang Theory Clip http://www.youtube.com/watch?v=Y5KaeCZ_AaY&safe=active (1:15) Doppler Effect Video http://www.youtube.com/watch?v=Kg9F5pN5tlI (2:01)

THE DOPPLER EFFECT What Causes the Doppler Effect When the source moves toward a listener, the _FREQUENCY__ of the wave is _HIGHER_ than it would be if the source were stationary. The Big Bang Theory Clip http://www.youtube.com/watch?v=Y5KaeCZ_AaY&safe=active (1:15) Doppler Effect Video http://www.youtube.com/watch?v=Kg9F5pN5tlI (2:01)