a thrrobbing variation in the loudness of sound caused by the inference when two tones of slightly diffrent frequencies are sounded together
comperssion: in mechaincs, the act of squeezing material and reducing its volume
forced vibration: the vibration of an object that is made to vibrate by another vibration object that is nearby
infrasonic:term applied to sound pitch too low to be heard by the human ear , that is below 20 hertz
natural frequency:a frequency at which an elastic object, once energized, will vibrate.
pitch:term that refers to how high or low sound quencies appear to be.
rarefaction:a disturbance in air in which the pressure is lowered . oppsite of compression.
resonance:a phenomenon that occurs when the fequency of forced vibration on an object matches that objects natural frequency.
ultrasonic:term applied to sound frequencies above 20000 hertz , the normal upper limit of human hearing.