Page 76 - Science Course 3 (Book 2)

Mo10-L4b: How Do you Hear Sounds?

Humans hear sounds with frequencies between
about 20 and 20,000 Hz.

Some animals can hear sounds with frequencies
greater than 100,000 Hz.

Frequencies Human and Animals Can Hear The vocal cords—
two membranes in
your neck above
Creature Frequency Range (Hz) your windpipe, or
trachea—allow you
Human 20 - 20,000 to produce sounds
of different pitches.
Dog 67 - 45,000

Cat 45 - 64,000

Bat 2,000 - 110,000 Sound and Loudness

Beluga Whale 1,000 - 123,000 Loudness is the human sensation of how much
energy a sound wave carries.
Porpoise 75 - 150,000
The amount of energy a sound wave carries depends
on its amplitude.

A shout carries more energy than a whisper.
Sound and Pitch

The pitch of a sound is the human sensation of how
high or low the sound seems to be. Loud
Sound
A sound wave with a higher frequency has a higher
pitch. A sound wave with lower frequency has a
lower pitch. Amplitude Sound
Soft

High Frequency Wave

PRESSURE TIME Cycles

<PERIOD> The amplitude of a sound wave depends on how
Low Frequency Wave close together or far apart the particles are in the
compressions and rarefactions.

PRESSURE TIME Amplitude

<--PERIOD-->
The high frequency wave sounds higher than the low
frequency wave.

68