Threshold of pain 120 phons 120 1 100 100 10-2 80 80 10-4 60 60 10–6 40 Threshold of hearing 40 10-8 20 20 10-10 10-12 20 50 100 500 1000 5000 10,000 Frequency (Hz) FIGURE 12-6 Sensitivity of the human ear as a function of frequency (see text). Note that the frequency scale is "logarithmic" in order to cover a wide range of frequencies. Sound level (dB) Intensity (W/m²)

Threshold of pain 120 phons 120 1 100 100 10-2 80 80 10-4 60 60 10–6 40 Threshold of hearing 40 10-8 20 20 10-10 10-12 20 50 100 500 1000 5000 10,000 Frequency (Hz) FIGURE 12-6 Sensitivity of the human ear as a function of frequency (see text). Note that the frequency scale is "logarithmic" in order to cover a wide range of frequencies. Sound level (dB) Intensity (W/m²)

University Physics Volume 1

18th Edition

ISBN:9781938168277

Author:William Moebs, Samuel J. Ling, Jeff Sanny

Publisher:William Moebs, Samuel J. Ling, Jeff Sanny

Chapter17: Sound

Section: Chapter Questions

Problem 39P: Bats use sound waves to catch insects. Bats can detect frequencies up to 100 kHz. If the sound waves...

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Bats use sound waves to catch insects. Bats can detect frequencies up to 100 kHz. If the sound waves travel through air at a speed of v=343 m/s, what is the wavelength of the sound waves?
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A man and a dog observe in the distance a loud nuclear explosion producing a sound having an effective power of 1.6 kW. The man does not hear the sound of the explosion while the dog can hear it. Knowing that humans can hear a sound from 0 dB and the dog can hear a sound from -6 dB, we want to estimate how far away the explosion is. We use the usual approximations and assume that the sound travels over the surface of a sphere. Keep in mind the speed of sound is 343 m/s. In between ? km and ? km do the man and the dog are from the explosion ?
How does our sensitivity to hearing different frequencies change with intensity? Compare a 1000 Hz sound at 60 dB (conversation level) to a 5000 Hz sound at 32 dB (also conversation level)
Loudspeakers can produce intense sounds with surprisingly small energy input in spite of their low efficiencies. Calculate the power input needed to produce a 90.0-dB sound intensity level for a 12.0-cmdiameter speaker that has an efficiency of 1.00%. (This value is the sound intensity level right at the speaker.)
As it approaches a boy standing on the road, an ambulance traveling at 100 km/hr blows its siren. Determine the frequency of the sound waves reaching the boy if the siren has a frequency of 460 Hz and the temperature of the air is at 0° C after it has passed the boy.
An explosion is recorded by two microphones that are 1 mile apart. Microphone M1 received the sound 2 seconds before microphone M2. Assuming sound travels at 1100 feet per second, determine the possible locations of the explosion relative to the location of the microphones.
Light travels faster than sound. During a thunderstorm, an approximately 5s time lapse between observing the lighting and hearing the thunder. Calculate approximately howfar in meters was the lightning flash?
A film depicts inhabitants of one spaceship (in outer space) hearing the sound of a nearby spaceship as itzooms past at high speeds. Critique the physics of this film.
Loudspeakers can produce intense sounds with surprisingly small energy input in spite of their low efficiencies. Calculate the power input needed (in W) to produce a 85.1 dB sound intensity level for a 15.5 cm diameter speaker that has an efficiency of 2.56%. (This value is the sound intensity level right at the speaker.)
With the advent of tiny, powerful rare earth magnets, and improvements in rechargeable battery and wireless technologies, wireless earbuds, like Apple’s AirPods (see the photo), enhance the enjoyment of listening to music, movies, and podcasts, and allow handsfree conversation. However, since the earbuds focus sound waves directly into the auditory canal at close distances, care must be taken to protect the eardrum from long-term exposure to high volumes (intensity levels). Hearing experts recommend listening at a maximum intensity level of 85 dB for no more than 8.0 hours a day. Assuming a constant intensity level of 85 dB, how much energy in mJ (1000 mJ=1Joule) does the eardrum absorb during 6.76 hours? Take the area of the eardrum to be 0.65 cm2 (1cm2 = 1x10-4 m2).
Find a clock that ticks. Then test to see which ear has the better hearing by covering one ear and finding how far away your open ear can hear the ticking; repeat for the other ear. Notice also how the sensitivity of your hearing improves when you cup your ears with your hands.