Most architects and interior designers these days are aware of the importance of acoustics in the design of an interior commercial space. Clients, and building occupants too, have become much more demanding in this regard, and now have high expectations of sound quality and noise minimization in interior spaces. Acoustics-related terms like unwanted noise, reverberation control, sound clarity, etc., are all high on the list when a design brief is being developed, especially where entertainment or public spaces are concerned.

Absorption of reflected sound or reverberation is usually achieved with the installation of sound absorbing or diffusing linings on walls and/or ceilings. These may take the form of pre-engineered acoustic panels faced, for example, with porous fabric like Sontext Serenity, or perforated timber like Murano Acoustics. The choice of facing is of course critical to achieve the “look” the interior designer requires. However, from a sound quality viewpoint, these decorative facings need to be acoustically transparent, and are primarily there to cover the acoustic absorbing infill underneath.

Available technical data for most acoustic absorber panels includes an N.R.C.  – a shorthand measure of sound absorption averaged over four centre frequencies (in accordance with the relevant Australian standard). This is fine as a general product comparison of sound absorption over the frequencies usually encountered in normal human speech and activity. However, when designing spaces where a wide range of sound frequencies may be encountered it pays to address sound absorption across the whole frequency spectrum. Music, performance, public address systems, indoor sports, etc. can all include sound frequencies outside of the NRC average. The result of such uncontrolled high and low frequency sound can render conversation unintelligible, and can ruin a listening experience. In particular, low frequency high energy sound is notoriously irritating for some listeners.

Thicker Acoustic Absorber Panels absorb more low frequency sound

Extra thickness sound absorbing wall treatments or acoustic absorber panels can be a solution in such cases. Compare the absorption at various frequencies on the accompanying graph. At higher frequencies the absorption at 25, 50 and 75mm thicknesses is similarly good – but at lower frequencies, around 125 or 250Hz – the thicker the panel, the higher the absorption.

It is therefore quite important to consider the end-use of the interior space when choosing materials for noise control or sound quality. This is the reason Sontext manufactures acoustic absorber panels to various thicknesses –  from 25mm thickness up to 100mm –  tested to provide predictable performance.