Acoustics – The Final Frontier

So we recently attended an event held at the newly established Dux Central here in Christchurch. Apart from the fantastic venue located next to the brand new Vodafone building, the event was also very educational. James Whitlock from Marshall Day Acoustics had a particularly interesting presentation called “The Acoustic Design of Modern Offices”. Now if you are not familiar with acoustics and the control of noise let me tell you it is a science! There is even a New Zealand acoustics organisation you can join for $50.00 a year. We thought it might be useful to pass on the nuggets of information as bite size chunks …. so here we go.

The basics of acoustics …

(RT) Reverberation Time. The time taken for sound in a room to decay by 60db. They demonstrated this by playing sound from a listening room which had almost no RT (no echo), through to sound being played from a large cathedral which had an 8 second RT time (high amount of echo).

(NRC) Noise Reduction Coefficient or sound absorption. When sound hits a surface, some of it is reflected and some of it is absorbed by the material. The simplest way to think about this is soft and fluffy equals sound absorptive (for example 0.7NRC = 70% absorption = good), as opposed to hard and smooth surfaces which are sound reflective. Think of a noisy cafe you recently visited which had very little sound absorbing surfaces. Autex Industries have a number of excellent acoustic products that specify a NRC rating.

(dBA/NC) Background Noise. Believe it or not there is actually desirable and non desirable background noise. Desirable background noise can be things like HVAC or babble (crowds of people). Undesirable nosies can be items like mechanical devices & traffic. The crossover from desirable to non desirable is measured in hertz. Those of you who remember the old graphic EQ on your stereo will understand that there are certain frequencies that favour the ear and there are those that don’t.

Speech Privacy. The modern open plan office was born from a number of factors that were influenced by the cost of real estate, recognition that collaboration enhances productivity and that space can influence how people work. One of the disadvantages with open plan is people’s lack of private space or speech privacy. This is often influenced by the level of surrounding vocals and babble or background noise.

With all of the above in mind, how do we create spaces that favour an acoustically friendly and supportive environment? Autex Industries have been leaders in this field for a long time. Recently they released a ceiling-based acoustic solution called Quietspace® Frontier™ which allows designers to be creative with the product.

To summarise, all designers and furniture providers should have a level of knowledge and understanding which allows them to incorporate acoustic considerations in their designs.