Waves & Sound

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c. Speed of sound

1) 332 m/s in air at 0 C.

2) Changes by 0.6 m/s for every Celsius degree from 0 C.

3) Subsonic – slower

4) Supersonic – faster than sound (Mach 1 = speed of sound)

5) Sonic boom (pressure cone)

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d. The Doppler effect – the change in pitch due to a moving wave source.

1) Objects moving toward you cause a higher pitched sound.

2) Objects moving away cause sound of lower pitch.

3) Used in radar by police and meteorologists and in astronomy.

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4. Musical sound

a. Noise has no pattern.

b. Music has a pattern and deliberate pitches.

c. Sound quality describes differences of sounds that have the same pitch and loudness.

d. Every instrument has its own set of overtones.

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e) Beats are pulsing variations of loudness caused by interference of sounds of slightly different frequencies.

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5. Uses of sound

a. Acoustics – the study of sound.

Soft materials dampen sound; hard materials reflect it (echoes and reverberations).

b. SONAR – Sound Navigation and Ranging (echolocation).

c. Ultrasound imaging

d. Kidney stones & gallstones.