the sound frequencies that elicit the sensation of hearing. For humans with average hearing, the audible range is usually specified as 20 Hz to 20 kHz. However, humans are much less sensitive to frequencies at the extremes of this somewhat arbitrary range. The frequency range of speech is approximately 100 Hz to 4 kHz. In audiometry, pure-tone thresholds are typically measured at frequencies from 250 Hz to 8 kHz. Also called audible range.