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Find a CD player and a CD that has rock music. Place the player on a light table, insert the CD into the player, and start playing the CD. Place your hand gently on the table next to the speakers. Increase the volume and note the level when the table just begins to vibrate as the rock music plays. Increase the reading on the volume control until it doubles. What has happened to the vibrations?
Describe how amplitude is related to the loudness of a sound.
Amplitude is directly proportional to the experience of loudness. As amplitude increases, loudness increases.
Identify common sounds at the levels of 10 dB, 50 dB, and 100 dB.
10 dB: Running fingers through your hair.
50 dB: Inside a quiet home with no television or radio.
100 dB: Take-off of a jet plane.
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?
(e)
A musician strikes the strings of a guitar such that they vibrate with twice the amplitude.
Intensity is the same for a sound wave as was defined for all waves; it is
Sound intensity level in units of decibels (dB) is
Six members of a synchronized swim team wear earplugs to protect themselves against water pressure at depths, but they can still hear the music and perform the combinations in the water perfectly. One day, they were asked to leave the pool so the dive team could practice a few dives, and they tried to practice on a mat, but seemed to have a lot more difficulty. Why might this be?
A community is concerned about a plan to bring train service to their downtown from the town’s outskirts. The current sound intensity level, even though the rail yard is blocks away, is 70 dB downtown. The mayor assures the public that there will be a difference of only 30 dB in sound in the downtown area. Should the townspeople be concerned? Why?
What is the intensity in watts per meter squared of 85.0-dB sound?
The warning tag on a lawn mower states that it produces noise at a level of 91.0 dB. What is this in watts per meter squared?
A sound wave traveling in air has a pressure amplitude of 0.5 Pa. What is the intensity of the wave?
What intensity level does the sound in the preceding problem correspond to?
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