Wave Properties
For a vibrating body or medium, the number of vibrations per unit time. For a wave, the number of crests that pass a particular point per unit time.
Frequency
A wave in which the medium vibrates parallel to (along) the direction in which the wave pulses travel. Sound consists of longitudinal waves.
Longitudinal Wave
The bouncing off of a wave from a surface. An echo is a reflection of sound.
Reflection
The sensation of a sound’s frequency.
Pitch
The setting up of vibrations in an object by a vibrating force.
Forced Vibration
The distance between successive crests, troughs, or identical parts of a wave.
Wavelength
A wave in which the medium vibrates perpendicular (at right angles) to the direction in which the wave travels.
Transverse Wave
The bending of a wave, either through a non-uniform medium or from one medium to another, caused by differences in wave speed.
Refraction
The characteristic sound of a musical instrument, which is governed by the number and relative intensities of partial tones.
Quality
A frequency at which an elastic object tends to vibrate, so that minimum energy is required to produce a forced vibration or to continue vibration at that frequency.
Natural Frequency
The speed with which waves pass a particular point.
Wave Speed
A stationary wave pattern formed in a medium when two sets of identical waves pass through the medium in opposite directions.
Standing Wave
A property of all types of waves; a result of superposing different waves, often of the same wavelength. Constructive interference results from crest-to-crest reinforcement; destructive interference results from crest-to-trough cancellation.
Interference
The lowest frequency of vibration, or the first harmonic. In a string, the vibration makes a single wave segment.
Fundamental Frequency
A wiggle in time.
Vibration
The SI unit of frequency. One hertz (symbol Hz) equals one vibration per second.
Hertz
The cone-shaped wave made by an object moving at supersonic speed through a fluid.
Shock Wave
A region of lessened pressure in the medium through which a longitudinal wave travels.
Rarefaction
A partial tone that is an integer multiple of the fundamental frequency. The vibration that begins with the fundamental vibrating frequency is the first harmonic, twice the fundamental is the second harmonic, and so on in sequence.
Harmonic
Re-echoed sound.
Reverberation
For a wave or vibration, the maximum displacement on either side of the equilibrium (midpoint) position.
Amplitude
The loud sound resulting from a shock wave.
Sonic Boom
The response of an object when a forcing frequency matches the natural frequency of the object.
Resonance
One of the frequencies present in a complex tone. When a partial tone is an integer multiple of the lowest frequency, it is a harmonic.
Partial Tone
A wiggle in both space and time.
Wave