Chapter 17: Q12PE (page 629)
What is the intensity in watts per meter squared of\(85.0\;{\rm{dB}}\)sound?
Short Answer
The intensity is \(3.2 \times {10^{ - 4}}\;{\rm{W/}}{{\rm{m}}^{\rm{2}}}\).
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Chapter 17: Q12PE (page 629)
What is the intensity in watts per meter squared of\(85.0\;{\rm{dB}}\)sound?
The intensity is \(3.2 \times {10^{ - 4}}\;{\rm{W/}}{{\rm{m}}^{\rm{2}}}\).
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By what fraction will the frequencies produced by a wind instrument change when air temperature goes from \({\rm{10}}{\rm{.0^\circ C}}\) to \({\rm{30}}{\rm{.0^\circ C}}\)? That is, find the ratio of the frequencies at those temperatures.
Suppose a person has a \({\rm{50 - dB}}\)hearing loss at all frequencies. By how many factors of\({\rm{10}}\)will low-intensity sounds need to be amplified to seem normal to this person? Note that smaller amplification is appropriate for more intense sounds to avoid further hearing damage.
In the clinical use of ultrasound, transducers are always coupled to the skin by a thin layer of gel or oil, replacing the air that would otherwise exist between the transducer and the skin. (a) Using the values of acoustic impedance given inTable 17.5calculate the intensity reflection coefficient between transducer material and air. (b) Calculate the intensity reflection coefficient between transducer material and gel (assuming for this problem that its acoustic impedance is identical to that of water). (c) Based on the results of your calculations, explain why the gel is used.
If a sound intensity level of\(0\;{\rm{dB}}\)at\(1000\;{\rm{Hz}}\)corresponds to a maximum gauge pressure (sound amplitude) of\(1{0^{ - 9}}\;atm\), what is the maximum gauge pressure in a\(60\;{\rm{dB}}\)sound? What is the maximum gauge pressure in a\(120\;{\rm{dB}}\)sound?
(a) Find the intensity in watts per meter squared of a \({\rm{60}}{\rm{.0 Hz}}\)sound having a loudness of\({\bf{60}}{\rm{ }}{\bf{phons}}\). (b) Find the intensity in watts per meter squared of a\({\rm{10,000 Hz}}\)sound having a loudness of\({\bf{60}}{\rm{ }}{\bf{phons}}\).
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