Diffraction can account for the ability of the AM radio waves (due to their low
frequency) to travel over a mountain, while FM and TV signals (due to their
higher frequencies) are blocked.
moves toward or away from a detector. It can affect the operation of
equipment used to detect and measure wave energy.
Characteristics of sound can be audible to the human ear or it can be outside
the hearing range.
Noise and tones are the two general groups that broadly classify all sounds.