\-our sense of whether a sound is “high” or “low”
\-determined by vibration frequency: hertz (Hz) or cycles/second
\-human hearing range is 20 to 20,000 Hz
\~infrasonic frequencies below 20 Hz
\~ultrasonic frequencies above 20,000 Hz
\-speech is 1,500 to 5,000 Hz, where hearing is most sensitive
\-most hearing loss with age is in range of 250 to 2,050 Hz