ABSTRACT
The ear’s extremely wide range of sensitivity is one of the most striking aspects of audition. The preceding chapters emphasized that hearing measurements are affected by psychophysical methods and other nonauditory factors; nevertheless, a reliable picture of auditory sensitivity has been provided by research over the years. Briefly, the ear is sensitive to a range of intensities from about 0 dB SPL (which is an amplitude of vibration of about the size of a hydrogen molecule) to roughly 140 dB (at which pain and damage to the auditory mechanism ensue). This dynamic range of the approximately 140 dB corresponds to a pressure ratio of 10 million to 1. In other words, the most intense sound pressure that is bearable is on the order of 10 million times as great as the softest one that is perceivable under optimum listening conditions. In terms of frequency, humans can hear tones as low as 2 Hz (although roughly 20 Hz is required for a perception of ‘‘tonality’’) and as high as about 20,000 Hz. Furthermore, the auditory system is capable of resolving remarkably small temporal differences.
