(This is an improved version of No 38 in Section 7.4). The loudness of sound is
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Question
(This is an improved version of No 38 in Section 7.4). The loudness of sound is measured in decibels in honor of Alexander Graham Bell, inventor of the telephone. A decibel is a dimensionless measure of the ratio of two pressures. If the sound pressure to be measured is P, then the sound loudness L in decibels is defined by L = 20log10(121.3 P/P0) where P0 is a reference pressure at the limits of audibility. Find the ratio P/P0 if the pressure P is caused by a rock band at 115 decibels. The pressure caused by the rock concert is times higher than the barely audible reference pressure. Hint: Use the basic properties of logs to isolate P.Explanation / Answer
115=20log10(121.3P / P0)
23/4=log10(121.3P / P0)
105.75=121.3P / P0
= 562341.325=121.3P / P0
P/P0 = 4635.95
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