pitch- Term that refers to how high or low sound frequencies appear to be.
infrasonic- Term applied to sound pitch too low to be heard by the human ear, that is, below 20 hertz.
Ultrasonic- Term applied to sound frequencies above 20,000 hertz, the normal upper limit for human hearing.
Compression- In mechanics, the act of squeezing material and reducing its volume. (b) In sound, a pulse of compressed air ( or other matter); opposite of rarefaction.
Rarefaction- A disturbance in air (or matter) in which the pressure is lowered. Opposite of compression.
Forced vibration- The vibration of an object tat is made to vibrate by another vibrating object that is nearby. The sounding board in a musical instrument amplifies the sound through vibration.
Natural frequency- A frequency at which an elastic object, once organized, will vibrate. Minimum energy is required to continue vibration at that frequency. Also called resonant frequency.
Resonance- A phenomenon that occurs when the frequency of forced vibrations on an object matches the object's natural frequency, and a dramatic increase in amplitude results.
Beats A throbbing variation in the loudness caused by the interference when two tones of slightly difference frequencies are sou