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Topic: Reverberation time

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	Reverberation Time
		The reverberant sound in an auditorium dies away with time as the sound energy is absorbed by multiple interactions with the surfaces of the room.
		The reverberation time is perceived as the time for the sound to die away after the sound source ceases, but that of course depends upon the intensity of the sound.
		The reverberation time is strongly influenced by the absorption coefficients of the surfaces as suggested in the illustration, but it also depends upon the volume of the room as shown in the Sabine formula.
	hyperphysics.phy-astr.gsu.edu /hbase/acoustic/revtim.html (494 words)

	Reverberation - Wikipedia, the free encyclopedia
		Reverberation time is the time required for a sound in a room to decay by 60 dB (called RT Reverberation time is defined for wide band signals.
		Reverberation effects are often used in studios to "smooth" sounds; the effect is commonly used on vocals to help remove inconsistencies in pitch.
		Reverberation time is often given as a measurement of decay time.
	en.wikipedia.org /wiki/Reverberation_time (1295 words)

	Reverberation Time - Acoustics.com
		Reverberation time (RT60) is defined as the time required, in seconds, for the average sound in a room to decrease by 60 decibels after a source stops generating sound.
		Reverberation time is the primary descriptor of an acoustic environment.
		Reverberation time is affected by the size of the space and the amount of reflective or absorptive surfaces within the space.
	www.reverberationtime.com (787 words)

	reverberation
		the reverberation time is defined as the time taken for a given sound to die away to a level of 60 decibels below its original level.
		for a general purpose auditorium for both speech and music, a reasonable reverberation time is taken to be in the range 1.5-2.5 seconds.
		auditoria are often designed to have a longer reverberation time for the lower frequency sound since the human ear discriminates against lower frequency sound more as the sound becomes quieter.
	www.bath.ac.uk /~ab8lam/labs/reverberation.htm (522 words)

	Millard - Acoustical Modeling of a Multipurpose Auditorium (Site not responding. Last check: 2007-11-04)
		Reverberation time is a measure of how long a sound lingers in a room.
		The reverberation times were imported into a spreadsheet and later used to confirm the validity of both the spreadsheet model(47k) and the CADP2 model.
		Although optimal reverberation time contour shown in Appendix A was not achieved, a significant rise in the overall reverberation time was attained.
	www.acs.psu.edu /users/mspencer/millard/millard_frame.html (2272 words)

	Reverberation
		To quantitatively characterize the reverberation, the paramater called the reverberation time is used.
		The delay between the direct sound and the first reflected sound is a significant characteristic for an auditorium, though not as important as the overall reverberation time.
		These plots can be extrapolated to give reverberation times for the room, which amount to about 0.5 s for the empty room and about 0.4 s for the occupied room.
	hyperphysics.phy-astr.gsu.edu /hbase/acoustic/reverb.html (277 words)

	Auditorium Acoustics
		During a continuous sound, the reverberant sound level is reached when the rate at which energy is supplied by the source is equal to the rate at which sound is absorbed by the room and its contents.
		Optimum reverberation time is a compromise between clarity (requiring short reverberation time), sound intensity (requiring a high reverberant level), and liveness (requiring a long reverberation time).
		The optimum reverberation time of an auditorium is dependent on the use for which it is designed.
	ccrma.stanford.edu /CCRMA/Courses/150/auditorium_acoustics.html (771 words)

	Reverberation
		W.C. Sabine established the official period of reverberation as the time required by a sound in a space to decrease to one-millionth of its original strength (i.e.
		Although it may not be realized consciously, reverberation is one of many cues used by a listener for orientation in a given space.
		Reverberation times of less than a second are necessary for speech comprehension.
	www.sfu.ca /sonic-studio/handbook/Reverberation.html (637 words)

	Reverberation
		Reverberation is defined as "the combined effect of multiple sound reflections within a room." (2) The reverberation characteristics of a room are affected by several factors: the shape and size of the room, the materials of which the room is constructed, and the materials present in the room.
		He found that the reverberation time was largely dependent on the contents of the room as well as the building materials used to construct the room.
		In order to model the reverberation time of a room via physical modeling, we must know several characteristics of that room; the most important are its size and shape, and the materials of which it is made.
	www.owlnet.rice.edu /~elec431/projects97/Phhh/reverb.html (2806 words)

	The Citizen Scientist (Site not responding. Last check: 2007-11-04)
		In "The Science of Sound" by Thomas Rossing, Richard Moore and Paul Wheeler (2002), the reverberation time is taken to be the time for the sound amplitude to fall to 1/1000 of its initial value.
		This means that the reverberation time is proportional to a length that characterizes the average distance between surfaces.
		The reverberation time is estimated by looking at the time scale (in seconds) on the horizontal axis.
	www.sas.org /tcstest/weeklyIssues_2005/2005-03-25/feature1/index.html (498 words)

	Church acoustics,church sound problems - speech intelligibility,reverberation time control, RT60,echo reduction,noise ...
		This time the reflection followed the direct signal with a time delay of about 65 - 3 = 62 ms and it could easily be heard as a separate signal.
		Reverberation can come from somewhere but it is an overflow of chaotic sound being stored in a reverberant space.
		Reverberation is a general din of noise that takes a long time to die out compared to the rapid sequences of speech sounds.
	www.church-acoustics.com /aa102.htm (2762 words)

	Harmony Central®: Effects Explained: Reverberation
		Reverberation is the result of the many reflections of a sound that occur in a room.
		Technically speaking, the reverb time is the amount of time it takes for sound pressure level or intensity to decay to 1/1,000,000th (60 dB) of it's original value (or 1/1000th of it's original amplitude.) Longer reverberation times mean that the sound energy stays in the room longer before being absorbed.
		The reverberation time is controlled primarily by two factors - the surfaces in the room, and the size of the room.
	www.harmony-central.com /Effects/Articles/Reverb (3352 words)

	David Griesinger
		In room acoustics the time it takes for the sound to decay 10 decibels (multiplied by six to be comparable in magnitude to the reverberation time) is usually used to describe reverberant level.
		Reverberation level matching experiments at the Massachusetts Institute of Technology and in our laboratory show that the reverberant profile - especially the amount of predelay - and the reverberation time have a large effect on our perception of the loudness of running reverberation.
		By the time it is finished the melody has jumped to a different critical band, and enough time has elapsed that the brain can identify the reverberation from the C as RR.
	world.std.com /~griesngr/PARIS.html (4429 words)

	Reverberation Time and 3D Audio Demos (Site not responding. Last check: 2007-11-04)
		Reverberation time refers to the amount of time required for the sound field in a space to decay 60dB, or to one millionth of the original power.
		Reverberation time is important because it can affect how well you understand speech, and it can change the way music sounds.
		The preferred reverberation time range for a space intended for speech is 1.0 second, or less.
	www.mcsquared.com /reverb.htm (1160 words)

	Quiet Classrooms - How to measure reverberation time?
		Reverberation time is defined as the length of time required for sound to decay 60 decibels from its initial level.
		Reverberation time is defined as the length of time required for sound to decay 60 dB from its initial level.
		Reverberation time is often calculated with the room unoccupied.
	www.quietclassrooms.org /library/test2.htm (541 words)

	Reverberation Time
		Reverberation time is the duration in seconds before the acoustic energy has dissipated 60dB.
		Without getting theoretical, it follows that reverberant noise depends on the amount of energy initially generated, the volume of the room in which it occurs, and the amount of absorption that takes place at the boundaries of the room (A living room with wall-to-wall carpeting and drapes is "softer" than a bare room.
		Through study and experimentation it has been concluded that reverberation time in seconds is equal to 0.05 times the volume of the room divided by the total number of sabines in the room.
	www.eckeleurope.co.uk /reverb.htm (957 words)

	Understanding Noise Control at QWYATT.com
		The formula allows for quick and easy calculations to estimate the existing reverberation time (RT) and to calculate how much additional treatment, using absorption materials, is required to obtain a lower RT value which is consistent with the intended use of the space.
		Reverberation time calculations using the Sabin Formula vary according to the volume of the space and the units of sound absorption or Sabins in the space.
		Reverberation time is the time measured in seconds that a sound of average loudness can be heard before it becomes completely inaudible under quiet ambient conditions.
	www.noisecontrol.net /architectural.html (1162 words)

	Functions - Acoustics - Performance
		Reverberation time is the time taken for the sound pressure level to drop by 60 dB after the generated noise has been stopped.
		Areas with a long reverberation time are referred to as being ’live’, e.g.
		As a rough guide the reverberation time of a room is approximately equal to the time it takes for loud clapping to become inaudible.
	www.owa.de /english/func_aku_raum.html (244 words)

	ReverbCalc
		Reverberation time is the time required for a steady-state sound to reach one millionth or -60dB of its original intensity.
		There are several models used in calculating the reverberation time but the first and most commonly used is that of Wallace Sabine (1868-1919).
		Example: Calculate the reverberation time at 125Hz, 500Hz, and 2000Hz for a classroom that is 8m wide by 12m long by 3m high.
	webphysics.davidson.edu /faculty/dmb/py115/ReverbCalc.html (289 words)

	Lenard Audio - Education - Acoustics
		Reverberation is sound reflecting off the floor, walls and ceiling and builds up to a percentage of the direct sound, and is different at all frequencies.
		Time is halved for each 3db increase (87dB/2hrs) (90dB/1hr) etc. Some people (not all) with hearing damage caused by loud noise, suffer hearing sensitivity loss in the 1K to 3K Hz range only, regardless of what frequencies caused the damage.
		Reverberant noise of city streets, work places and recreational venues, is often in excess of what is safe to experience.
	www.lenardaudio.com /education/04_acoustics.html (3747 words)

	Physics 4830 Course Notes
		Reverberation Time is the time it takes the sound to decay away 60 dBs.
		Reverberation times should be consistent with visual cues, which tell us what the size of the room is. A desirable reverberation time also depends on the type of music.
		where T is the reverberation time, V is the volume of the room and A is the surface area of absorbing material.
	www.colorado.edu /physics/phys4830/phys4830_fa01/lab/n0920.htm (767 words)

	Beethoven Pianos - Room Acoustics
		In the study of auditorium acoustics, great emphasis is placed on the reverberation time—the amount of time it takes for a burst of sound to decay by sixty decibels (to one-millionth of its original intensity).
		Too short a reverberation time will thus create a "dry" sound, and the performer may have to work too hard to be heard.
		Although it's not practical, of course, for a homeowner to measure reverberation time, it is possible, when designing a small room, to adjust it to some extent to one's taste an to balance the treble and bass.
	www.beethovenpianos.com /tuning4.php (1222 words)

	Reverberation Effect: Theory & Practice
		Time of reverberation is duration of signal damping by 60 dB from the starting value.
		According to time of reverberation and its depth in a natural acoustic environment it's possible to estimate dimensions of the room and its acoustic properties.
		Usually, to reach the sense of integrity of space a reverberation type like Hall (Room, Live) is used for the mix on the whole; and for separate instruments of groups of instruments it's possible to use additional processing by the reverb processor to get special effects.
	www.digit-life.com /articles2/theoryofreverb/index.html (2105 words)

	Room Acoustics and Reverberation Time Lab
		The initial time delay between the direct sound and the first reflected sound, and the initial reverberation consisting of the first few reflections are very important in the perception of the acoustical quality of a room.
		This expression for the reverberation time was derived around 1895 by the father of modern architectural acoustics, Clement Sabine.
		Usually, the reverberation time is measured in octave bands centered at 125, 250, 500, 1000, 2000, and 4000 Hz.
	www.kettering.edu /~drussell/GMI-Acoustics/Reverb.html (2416 words)

	Modern Recording Overview of Xovers
		The time difference between when the listener hears the direct sound and when the reflection (echo) is heard is referred to as the echo delay time.
		Auditoriums and concert halls are frequently evaluated on the basis of their "reverberation time, " that is, the time that it takes for a sound to decay away to inaudibility.
		However, if one signal is delayed slightly in time and then the [two] signals are combined, the net result is a series of cancellations of certain frequencies, the canceled frequencies depending on the precise amount of time delay between the two signals.
	www.trueaudio.com /at_echo.htm (3890 words)

	Reverberation Time Calculation
		When sound waves contact a room surface such as a ceiling, wall or floor, a portion of the sound energy is reflected back into the room, and the rest is considered to be absorbed primarily by conversion into heat due to friction within a porous material, or by vibration of a solid material.
		The level of the reverberant sound within a room is dependant on both the volume of the room and the amount of sound absorption installed within the room, such that small hard surfaced rooms are "louder" than large well treated rooms.
		Specifically, the reverberation time is the time it takes for reflected sound within a space to decrease by 60 dB after the sound was made, for instance, the time it takes before you cannot hear a loud clap.
	www.armstrong.com /reverb/main.jsp?page=glossary (886 words)

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