| Comments |
"The intensity, or loudness of a sound depends on the amplitude of the sound waves, or the pressure differences between a high-pressure region of compression and a low-pressure region of rarefaction.Within the hearing range, the greater the amplitude, the louder the sound. Human ears can detect a wide range of sound intensities, from the slightest whisper to the painfully loud takeoff of a jet. Loudness is expressed in decibels (dB), which is a logarithmic measure of intensity compared with the faintest sound that can be heard-the hearing threshold. Because of the logarithmic relationship, every 10 decibels indicates a tenfold increase in loudness. A few examples of common sounds illustrate the magnitude of these increases (table 6-6). Note that the rustle of leaves at 10 dB is 10 times louder than the hearing threshold, but the sound of a jet taking off at 150 dB is a quadrillion (a million billion) times, not 150 times, louder than the faintest audible sound. Sounds greater than 100 dB can permanently damage the sensitive sensory apparatus in the cochlea." |