Acoustic Equalization is part of every day life and is used extensively to amplify and control musical performance. Unwanted reverberation noise can cause great discomfort and pose a serious health hazard, greatly reducing efficiency in the workplace and quality of life.

Minimalist design themes produce architecturally pleasing environments. However such designs, generally incorporate hard, flat surfaces, which produce reverberation and exacerbate unpleasant noise.

Properly controlled acoustics are becoming increasingly important for architects, designers and builders internationally as they strive to meet both design criteria and health and safety standards.

The method of quantifying reverberation time was first developed in 1900 by Wallace Sabine, an American Physicist.

• T = Reverberation time
• V = Volume in m3
• A = Average absorption coefficient of the room
• S = Total surface area of the room in m2

Both the design and the analysis of room acoustics begin with this equation. Using the equation and the absorption coefficients of the materials from which the walls are to be constructed, an approximation can be obtained for the way in which the room will function acoustically. Absorbers and reflectors, or some combination of the two, can then be used to modify the reverberation time and its frequency dependence, thereby achieving the most desirable characteristics for specific uses. Representative absorption coefficients—showing the fraction of the wave, as a function of frequency, that is absorbed when a sound hits various materials—are given in the Table. The absorption from all the surfaces in the room are added together to obtain the total absorption (A).

The tendency of a space to maintain sound energy is quantified by its “reverberation”. One could describe reverberation as a smooth, slowly decaying echo.

• Indoor swimming pools
• Art galleries
• Museums
• Open plan offices
• Restaurants
• Civic buildings
• Hospitals
• Libraries
• Shopping malls
• Lecture theatres
• Meeting rooms
• Entrance halls
• Dining areas
• Schools and Colleges
• Reception areas
• Interview rooms

Good acoustic design must take account of all these possible problems while emphasizing the desired acoustic features. One of the problems in a large auditorium involves simply delivering an adequate amount of sound to the rear of the hall. The intensity of a spherical sound wave decreases in intensity at a rate of six decibels for each factor of two increase in distance from the source, as shown above. If the auditorium is flat, a hemispherical wave will result. Absorption of the diffracted wave by the ceiling/ floor or audience near the bottom of the hemisphere will result in even greater absorption, so that the resulting intensity level will fall off at twice the theoretical rate, at about 12 decibels for each factor of two in distance. Because of this absorption, the ceiling of an auditorium are generally sloped downward toward the rear.

The human ear has become «more sensitive» and it reacts negatively to reverberations and other disturbing acoustic effects.
Our modern society is highly sensitized to sounds, special tones and noises: the human ear has become «more sensitive» and it reacts negatively to reverberations and other disturbing acoustic effects. Therefore, more attention is currently being paid to acoustic requirements. Increasing numbers of studies about concentration problems and noise-induced stress (in schools and offices, etc.) prove that poor room acoustics are unhealthy in the long  term, and they can lead to physical and psychological disorders and damage.

Concert halls, auditoriums, lecture theatres and other large open-plan areas are not the only locations where room acoustics must meet exacting requirements nowadays. More and more frequently, acoustic issues are also to the fore when it comes to the construction of industrial and office buildings, as well as residential accommodation. The same issues arise in many building renovation or refurbishment projects (such as balcony undersides).