| American Heritage Dictionary of the English Language 3rd ed | |
|---|---|
| "Under very favorable conditions most individuals can obtain tonal characteristics as low as 12 cycles | "For auditory signals and human listeners, the accepted range is 20Hz to 20kHz, the limits of human hearing"• , the least amount of intensity is needed to reach threshold in the 2000 to 5000 Hz range"• "hearing is most sensitive i |
.