Practice Set 1 — Production and Propagation of Sound
Vibrations, medium, the human ear and voice.
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Practice Set 2 — Characteristics of Sound and Noise
Amplitude, frequency, loudness, pitch, audible range, noise pollution.
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Quick Q&A Before You Revise
Why does the sound of a bell fade away as air is removed from a jar around it?
As the air is pumped out there are fewer and fewer particles to carry the vibrations. With no medium, no sound can travel, so the bell becomes inaudible even though it is still vibrating.
Two sounds have the same loudness but one is shrill and the other is flat. What differs?
Their frequencies differ. The shrill sound has a higher frequency (higher pitch); the flat sound has a lower frequency (lower pitch). Equal loudness means their amplitudes are similar.
Is ultrasound audible to human beings?
No. Ultrasound has a frequency above 20,000 Hz, beyond the human audible range, though some animals such as dogs and bats can hear it.