The part of a longitudinal wave where the particles of the medium are close together.

A wave that appears to stay in one place and does not seem to move through a medium, due to a repeated pattern of interference.

The matter through which a wave travels.

A wave that is dependent upon a medium in order to travel.

The distance from one crest to another (or one trough to another).

When two waves interfere in such a way that a the crests line up with the troughs and result in a wave with less amplitude.

When two waves interfere in such a way that a crest becomes higher or a trough becomes lower (due to the two crests or troughs hitting the medium at the same time)

A unit that compares the intensities of different sounds.

How we perceive the frequency of a sound wave.

The change in frequency of a wave as its source moves in relation to an observer.

Sound waves with frequencies below 20 hertz (too low for humans to hear).

The process of using reflected sound waves to find objects; used by animals such as bats

The number of complete wavelengths that pass a point in a given time.

The bending of a wave as it moves around an obstacle or passes through a narrow opening.