What is Reverb?

Reverb or reverberation is a term that refers to the persistence of sound that continues because of its interaction with the surrounding environment even after the source of that sound has ceased.  Consisting of a series of echoes, reverb is a crucial component of how sound is perceived and is an important aspect of acoustics.  This is because a sound can vary greatly based on the number of echoes, how those echoes reflect upon the surrounding environment, and how fast those echoes decay.  This is why everything from actual space dimensions to the materials within that space is significant for a proper control of reverberance.

It is within large spaces consisting or hard, firm surfaces that the echoes of a sound last for the longest time after the initial sound ceases.  I’m sure most of you have heard the reverberance within a large auditorium, a church, or some other large structure.  On the other hand, small rooms like those found in many homes more effectively absorb the sounds due to the confined space and the soft materials that are often present.

Whether the environment is a pleasant home atmosphere or a business space serving the public in some way, there are several reasons why there might be a need to control reverberation.  This can include the desire to maximize sound quality, improve the intelligibility of speech, or reduce the intensity of annoying noise or clamor.

 

Reverberance and Absorption

In order to control reverberation, it is necessary to alter your environment so that it provides the proper amount of sound absorption necessary to meet your specifications.  This sometimes requires using acoustic absorbers since they are soft and excel at absorbing the sound.  There are now sound absorbing materials available for the roof, walls and other parts of the interior, such as an absorbing wood finish for a wall or ceiling tiles composed of compressed mineral wood.  And if you are preparing a studio or recording space, you will need to have sound absorbers to ensure that the recording environment is properly setup to best control reverb since sound absorbing materials can improve the quality of sound while recording. Sound recording options for absorption can include acoustic panels, studio foam, baffles, cotton-fiber panels, or other materials.

Whatever absorbing materials are selected for your home, business, or recording studio, it is often important that their installation does not intrude on the pleasant design aspects of the structure.  This is why micro-perforated absorbers are now in common use since they have low visibility when applied to wood and plastic surfaces.  And acoustic plasters are now being used on walls and roofs for the very same reason.  With sustainability of absorbing materials and thermal efficiency also being important in many cases, those working to control reverberance must sometimes take a large number of factors into consideration.

Digitally Simulating Reverberance

When it comes to the output of sound from electronics such as public announcement systems and sound equipment, there are other methods to control reverberance in addition to the natural environmental factors.  Devices such audio cards, effects processors, synthesizers, or other audio applications can help in modifying reverb by imitating a desired environment.  For example, you can utilize this equipment to simulate the sound of an auditorium thousands of feet in diameter with hard floors and walls even though you are in a small room with soft materials and carpet.

Those skilled in digital signal processing (DSP) can replicate a desired specific environment by simulating the acoustics that would take place within the real space they are imitating.  This includes determining the original sound reflections, echoes, and echo decay for various frequencies.  With the modern technology available today, it is absolutely amazing what these DSP designers can accomplish.

It is important to remember that the major factor in reverberance control is sound absorption and it is by altering the degree of absorption that one can effectively manage reverberance.  The key to success is to use the proper materials and/or tools to create the perfect environment that produces the acoustics that you desire.

-By John Redick

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