Acoustic Optimization

SEFAR LIGHTFRAME – Acoustic Optimization

By: Ron White, Technical R&D Manager, Decoustics


A) Sound focusing
B) Flutter echo
C) Simple reflection

The problem of poor acoustics is prevalent

in a wide variety of building and indoor environment types. Schools, offices, atriums, cafeterias, libraries, swimming pools, air terminals, correctional institutions and public buildings are very often not adequately acoustically treated. Excessive reverberation and poor speech intelligibility can lead to high stress levels, fatigue, anxiety, poor produc- tivity, headaches, frustration and low tolerance, poor attention spans and if continued to physical illness.

The acoustic properties of the indoor environment affect everyone in that environment, from office workers (work efficiency), to school children and teachers (learning ability), to the performers and audience at a show. Commercially, the acoustic environment also affects the leaseability, rentability, or saleability of a property or individual rooms.

Unlike a lot of annoying distractions, such as the sun reflecting off a nearby window into your eyes, escape from a poor acoustic environment is very difficult for a lot of people, where safety (reduced ability to identify and respond to warning signals), and communication are compromised.

For every space/room there is an optimal reverberation time (echo), which is dependent on the physical size of the room and the end use of the room (eg. speech, music, choir etc.). The amount of reflected sound (and number of reflections) must be controlled in order to achieve optimum or near optimum conditions. Most rooms/spaces can be corrected with the use of appropriate acoustic materials (sound absorbing, sound diffusing, and sound reflecting).

A consultant will be able to determine how much additional absorption, diffusion, and reflection

(if any) is required and the location of any corrective treatment.

There are basically three types of 'acoustical defects' that occur in buildings:

The straight forward reflection. This can be from the ceiling, floor, or the walls. A sound hits the hard (non-acoustically absorbing) surface and is reflected back to another location. (Like a rubber ball hitting a concrete wall).

Flutter Echo. This occurs between two parallel, acoustically reflective, surfaces. Either between the floor and ceiling, or more commonly between two walls. Basically the sound is reflected back and forth a number of times before it finally loses energy and fades away.

Sound Focusing. This occurs when sound hits a curved acoustically reflective surface, and is reflected to the centre point of the radius (The focal point). The majority of sounds hitting this surface reflect to the same location.

The area that generally produces the most dramatic acoustic change is the ceiling. If an area

has no acoustically absorptive treatment in the ceiling (often an existing metal deck or gypsum board), the addition of ceiling panels or baffles will generally have a noticeable impact on the acoustics. This treatment, however, should be complemented with acoustic treatment to the walls, to achieve the desired reverberation time and acoustic conditions. Treatment of the walls and not the ceiling (e.g. commercial spaces, gymnasiums and swimming pools), can in some instances, produce very little change to the reverberation time for the amount of dollars spent.

When acoustically treating problem areas, it is important to realize there will be an optimum amount of treatment required. There is a point where adding acoustically absorptive panels is no longer cost effective. The same is true for the surfaces to be treated. There is no point in locating all of the acoustic treatment on one wall, or on the ceiling – even if it does theoretically contain all the absorption required for that particular room. Strategic location and optimum amount of absorption will provide a cost effective solution for rooms where reflected sound (high reverbe- ration time) is a problem.

Effective acoustic optimization will result in better working, learning, and listening conditions, better productivity and a little less stress for everyone. Good acoustic environments should enhance the rentability or leaseability of a property, and provide a method of generating additional income for building owners, governing boards, and facility managers.

About Decoustics

For over 35 years, Decoustics has served as a leader in interior architectural products through the design and manufacture of innovative acoustical ceiling panels, wall panels and systems.

A CertainTeed Ceilings company, Decoustics specializes in custom-engineered, high-precision solutions backed by world-class expertise and technical support. For more information, visit


Decoustics now includes SEFAR LIGHTFRAME illuminated modular fabric ceiling system in its product offerings. A perfect fit, considering LightFrame is the only fabric ceiling system available that can provide both light diffusion and acoustic improvements for a multitude of interior or exterior ceiling and canopy soffit applications.