Human beings can hear sound between the frequencies from 16-20 Hz to about 20,000 Hz. Speech requires the use of sounds, which are both fricative and labial. These sounds are produced between the frequencies of 2048 to 8192 Hz, but humans can hear speech between the frequencies of 512 to 2048 Hz. Sounds above the audible level for humans are ultrasounds and are audible by bats and dogs (or even Superman). Sounds below the audible level for humans are called infrasound.

Constant exposure to high pressure and frequency or even age can damage hearing, and most people cannot hear upper level sounds by certain ages. Hearing aids are now available to assist people with hearing difficulties. These are electronic devices the most modern of which can most inconspicuously fit behind ones ear.