It has been suggested that this article or section be merged into reverberation. (Discuss) Reverberation time is a measurement used in acoustic design. It is defined as the length of time taken for a sound presure to decay 60 dB after the source has ceased transmitting. Reverberation time is defined for wide band signals. When talking about the decay of an individual frequency, the term decay time is used. Wikipedia does not have an article with this exact name. ...
When sound is produced in a space, multiple reflections may build up and blend together, creating reverberation, or reverb. ...
Various meters Measurement is the process of estimating the ratio of a magnitude of a quantity to a unit of the same type. ...
Acoustics is a branch of physics and is the study of sound, mechanical waves in gases, liquids, and solids. ...
A schematic representation of hearing. ...
The decibel (dB) is a measure of the ratio between two quantities, and is used in a wide variety of measurements in acoustics, physics and electronics. ...
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Explanation
This time varies directly with the dimensions of room but inversely as the absorption present.
In acoustics, rooms with smaller reverberation times are appropriate for speech, whereas spaces designed for music require longer reverberation times. Acoustics is a branch of physics and is the study of sound, mechanical waves in gases, liquids, and solids. ...
Basic factors that affect a room's reverberation time include the size and shape of the enclosure as well as the materials used in the construction of the room. Every object placed within the enclosure can also affect the reverberation time, including people and their belongings.
Reverberation time RT60 is most commonly calculated by Sabine's Formula. For metric or SI calculations the formula is: In mathematics and in the sciences, a formula is a concise way of expressing information symbolically (as in a mathematical or chemical formula), or a general relationship between quantities. ...
 where
T is the reverberation time in seconds,
V is the volume of the room in cubic meters,
A is the average absorption coefficient of the room, and
S is the total surface area of the room in square meters
For non metric calculations Sabine's Formula is given by:
 where
T is the reverberation time in seconds,V is the volume of the room in cubic feet,A is the average absorption coefficient of the room, andS is the total surface area of the room in square feet.
The reverberation time RT60 and the volume V of the room have great influence on the critical distance dc (conditional equation): Volume, also called capacity, is a quantification of how much space an object occupies. ...
In audio physics, the distance at which the sound pressure level of the direct and the reverberant field are equal. ...
 critical distance rH in m
volume V in m3
reverberation time RT60 in s [edit]
Absorption The absorption coefficient of a material is a number between 0 and 1 which indicates the proportion of sound which is absorbed by the surface compared to the proportion which is reflected back into the room. A large, fully open window would offer no reflection as any sound reaching it would pass straight out and no sound would be reflected. This would have an absorption coefficient of 1. Conversely, a thick, smooth painted concrete ceiling would be the acoustic equivalent of a mirror, and would have an absorption coefficient very close to 0. [edit]
Measurement of Reverberation Time Historically reverberation time could only be measured using a level recorder (a plotting device which graphs the noise level against time on a ribbon of moving paper).
A Loud noise is then produced, and as this dies away the trace on the level recorder will show a distinct slope. Analysis of this slope reveals the measured reverberation time.
Modern digital sound level meters carry out this analysis automatically, on digital data. Integrating sound level meter in dB(A) A sound level meter is used to measure sound levels, usually in terms of subjective loudness. ...
Two basic methods exist for creating a sufficiently loud noise (which must have a defined cutt off point).
Impulsive noise sources such as a blank pistol shot, or balloon burst may be used to measure the "Impulse Response" of a room.
A random noise signal such as pink noise or white noise may be generated through a loudspeaker, and then turned off. This is known as the "interrupted method", and the measured result is known as the interrupted response.
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See also Convolution reverb | reverberation | Decay Convolution reverb is a type of process in which a physical space is sampled by means of an impulse response (IR), so it can be used in audio applications. ...
When sound is produced in a space, multiple reflections may build up and blend together, creating reverberation, or reverb. ...
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External links - Calculation of the reverb time RT60 - decay after Sabine
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