17.3 Sound Intensity and Sound Level

Power per unit area and sound pressure, and the logarithmic decibel scale that turns intensity ratios into sound levels.

College Physics 2e, 17.3 Sound Intensity and Sound Level

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12 exercises

17.3 Exercise 1

Describe how amplitude is related to the loudness of a sound.

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17.3 Exercise 2

Identify common sounds at the levels of 10 dB, 50 dB, and 100 dB.

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17.3 Exercise 3

In order to waken a sleeping child, the volume on an alarm clock is tripled. Under this new scenario, how much more energy will be striking the child’s ear drums each second?

twice as much
three times as much
approximately 4.8 times as much
six times as much
nine times as much

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17.3 Exercise 7

What is the intensity in watts per meter squared of 85.0-dB sound?

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17.3 Exercise 9

A sound wave traveling in $20ºC$ air has a pressure amplitude of 0.5 Pa. What is the intensity of the wave?

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17.3 Exercise 11

What sound intensity level in dB is produced by earphones that create an intensity of $4.00 \times \text{10}^{−\text{2}} \text{W}/\text{m}^{\text{2}}$ ?

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17.3 Exercise 13

(a) What is the decibel level of a sound that is twice as intense as a 90.0-dB sound? (b) What is the decibel level of a sound that is one-fifth as intense as a 90.0-dB sound?

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17.3 Exercise 15

(a) How much more intense is a sound that has a level 17.0 dB higher than another? (b) If one sound has a level 23.0 dB less than another, what is the ratio of their intensities?

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17.3 Exercise 17

If a large housefly 3.0 m away from you makes a noise of 40.0 dB, what is the noise level of 1000 flies at that distance, assuming interference has a negligible effect?

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17.3 Exercise 19

The amplitude of a sound wave is measured in terms of its maximum gauge pressure. By what factor does the amplitude of a sound wave increase if the sound intensity level goes up by 40.0 dB?

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17.3 Exercise 21

An 8-hour exposure to a sound intensity level of 90.0 dB may cause hearing damage. What energy in joules falls on a 0.800-cm-diameter eardrum so exposed?

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17.3 Exercise 23

Sound is more effectively transmitted into a stethoscope by direct contact than through the air, and it is further intensified by being concentrated on the smaller area of the eardrum. It is reasonable to assume that sound is transmitted into a stethoscope 100 times as effectively compared with transmission though the air. What, then, is the gain in decibels produced by a stethoscope that has a so…

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