Introduction to room acoustics

 

It’s never been more important to get your room acoustics right. Here’s why.

Look at the growth in popularity of open plan offices. When designed well, they encourage collaboration and communication. Not to mention the savings gained from getting more workers in a smaller space. However, badly designed room acoustics come at a cost – to productivity and morale. A study by real estate company Savills and the British Council for Offices found: ’Noise level also ranks highly amongst the factors impacting employee’s wellbeing’.

Room acoustics is also a major issue for the restaurant/cafe/bar industry. In a recent survey by restaurant reviews website Zagat, noise was #2 in the list of common complaints (behind service).

The physics of sound, coupled with the complexity of modern-day buildings, mean that it’s impossible to apply a one-size-fits-all approach to room acoustics. So whether you’re planning for acoustics in new builds and fit-outs, or looking to fix existing builds, here’s what you need to know.

 

Sound absorption

 

When sound strikes a surface in a room, some of the sound bounces back into the room. The rest of it is absorbed by the surface’s fibres.

This means that wherever you get a room with lots of hard surfaces – like windows, metal ceilings or bare floors – there will be less sound absorption. The result? A noisier environment. So it’s important you take action. Especially when you’re dealing with rooms that will contain lots of people talking, moving around and making noise.

 

Noise reduction coefficient (NRC)

 

When choosing a surface material, you need to know its NRC. This is a lab-tested scale telling you how much sound energy can be absorbed. The scale runs from 0 to 1 – with 0 representing perfect reflection, and 1 representing perfect absorption. Acoustic material with a 0.90 NRC rating will absorb 90% of sound in a space, and reflect the remaining 10%.

With increments of 0.05, the NRC is the average across four frequencies you’ll find in everyday life, including human speech. These are: 250Hz, 500Hz, 1000Hz and 2000Hz. For effective room acoustics design, you’ll need to keep track of which of these frequencies you’re trying to reduce, control or shape.

 

And finally

 

It’s important to remember that sound absorption is different to sound proofing. Sound absorption is all about improving the sound experience, by controlling noise, reverberations and echoes. Sound proofing is about insulating a room so that it stops sound from entering or leaving.

When it comes to room acoustics, the design should ideally be factored in from the start. Of course, in practice this isn’t always the case. So to give your sound the best possible platform, first decide on the result you want. From there you can work out what you need to treat, and how best to achieve it.

Got any questions? Feel free to contact us – we’re always happy to give advice and talk about room acoustics!

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