Chapter summary
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10.6 The physics of hearing [NOT IN CAPS]
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Chapter summary
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Sound waves are longitudinal waves
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The frequency of a sound is an indication of how high or low the pitch of the sound is.
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The human ear can hear frequencies from 20 to \(\text{20 000}\) \(\text{Hz}\). Infrasound waves have frequencies lower than \(\text{20}\) \(\text{Hz}\). Ultrasound waves have frequencies higher than \(\text{20 000}\) \(\text{Hz}\).
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The amplitude of a sound determines its loudness or volume.
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The tone is a measure of the quality of a sound wave.
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The speed of sound in air is around \(\text{340}\) \(\text{m·s$^{-1}$}\). It is dependent on the temperature, height above sea level and the phase of the medium through which it is travelling.
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Sound travels faster when the medium is hot.
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Sound travels faster in a solid than a liquid and faster in a liquid than in a gas.
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Sound travels faster at sea level where the air pressure is higher.
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The intensity of a sound is the energy transmitted over a certain area. Intensity is a measure of frequency.
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Ultrasound can be used to form pictures of things we cannot see, like unborn babies or tumours.
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Echolocation is used by animals such as dolphins and bats to “see” their surroundings by using ultrasound.
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Ships use sonar to determine how deep the ocean is or to locate shoals of fish.
Physical Quantities |
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Quantity |
Unit name |
Unit symbol |
Velocity (v) |
metre per second |
\(\text{m·s$^{-1}$}\) |
Wavelength (λ) |
metre |
m |
Amplitude (A) |
metre |
m |
Period (T) |
second |
s |
Frequency (f) |
hertz |
Hz (\(\text{s$^{-1}$}\)) |
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10.6 The physics of hearing [NOT IN CAPS]
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