Advanced Acoustics - Studio Acoustic Treatment

Glossary

ABSORPTION
In acoustics, it is the changing of sound energy into heat.
ABSORPTION COEFFICIENT
It is the fraction of sound energy that is absorbed at any surface. It has a value between 0 and 1 and varies with the frequency and angle of incidence of the sound.
ACOUSTICS
It is the science of sound. It can also refer to the effect a given environment has on sound.
ANECHOIC CHAMBER
It is a room designed to restrain internal sound reflections. It is used for acoustical measurements.
AUDIO FREQUENCY
It is an acoustical or electrical signal of a frequency that falls within the audible range of the human ear, usually taken as 20 Hz to 20 kHz.
AXIAL MODE
This is the room resonances associated with each pair of parallel walls. SEE MODE.
BASS
The lower range of audible frequencies
BOOMY
It is the colloquial expression for excessive bass response in a recording, playback or sound reinforcing system.
COLOURATION
It is the distortion of a signal detectable by the ear.
CYCLES PER SECOND
It is the frequency of an electrical signal or sound wave. This is measured in hertz (Hz).
dB
See decibel
DECIBEL
The human ear responds logarithmically and it is convenient to deal in logarithmic units in audio systems. The bel is the logarithm of the ratio of two powers and decibel is 1/10 bel.
DIAPHRAGM
It is a surface that vibrates in response to sound or is vibrated to emit sound, such as loudspeakers and microphones. It is also applied to wall and floor surfaces vibrating in response to sound or transmitting sound.
DIFFUSER
It is a proprietary device for the diffusion of sound through reflection-phase-grating means.
ECHO
It is a delayed return of sound that is perceived by the ear as a discrete sound image.
FLUTTER
It is a repetitive echo set up by parallel reflecting surfaces.
FREQUENCY
It is the measure of the rapidity of alterations of a periodic signal, expresses in cycles per second or Hz.
HERTZ
It is the unit of frequency, abbreviated Hz, the same as cycles per second.
kHz
1,000 Hz.
LAW OF THE FIRST WAVE FRONT
The first wave front falling on the ear determines the perceived direction of the sound.
MODE
It is a room resonance. Axial modes are associated with pairs of parallel walls. Tangential modes involve four room surfaces and oblique modes all six surfaces. Their effect is greatest at low frequencies and for small rooms.
NODE
It is the point of no vibration.
OBLIQUE MODE
This is the room resonances associated with all 6 walls. SEE MODE.
PASSIVE ABSORBER
It is a sound absorber that dissipates sound energy as heat.
REFLECTION
For surfaces large compared to the wavelength of impinging sound, sound is reflected much as light is reflected, with the angle of incidence equaling the angle of reflection.
RT60
Reverberation time.
REVERBERATION
It is the tailing off of sound in an enclosure because of multiple reflections from the boundaries.
REVERBERATION TIME
The time required for the sound in an enclosure to decay by 60dB.
ROOM MODE
It is the normal modes of vibration of an enclosed space. SEE MODE.
SABIN
It is the unit of sound absorption. One square foot of open window has absorption of 1 sabin.
SLAP BACK
It is a discrete reflection from a nearby surface.
SOUND ABSORPTION COEFFICIENT
It is the practical unit between 0 and 1 expressing the absorbing efficiency of a material. It is determined experimentally.
STANDING WAVE
It is a resonance condition in an enclosed space in which sound waves traveling in one direction interact with those traveling in the opposite direction, resulting in a stable condition.
TANGENTIAL MODE
A room mode produced by reflections off four of the six surfaces of the room. SEE MODE.
TREBLE
This is the higher frequencies of the audible spectrum.
WAVE
It is the regular variation of acoustical pressure.
WAVELENGTH
It is the distance a sound wave travels in the time it takes to complete one cycle.