The dark art of acoustics

Life is busy, and living in a city, life can also be very noisy.  Your home should be your sanctuary, and a place to be able to relax, but it can be difficult to relax in a noisy environment.

We all know how important acoustics are in public buildings, especially theatres and libraries, but the importance of acoustics in your home is often overlooked as people focus on thermal performance and aesthetics.

There are three basic areas of acoustics we need to think about:

1.       Exterior noise control

2.       Inter-space noise control

3.       Interior space acoustics

If you’re controlling the exterior noise, primarily you’re trying to minimise traffic noise.  This is best achieved close to the source, so a solid fence is in order – this won’t keep the urban planners happy, but you will get a quieter home – at least on the ground floor.

The next point to deal with exterior noise is the exterior of the building.  Note that walls are good (especially dense walls like concrete), and windows are bad. 

Acoustic urban myth number one about to be destroyed … double glazing does not help with acoustics, and in some circumstances the sound may actually be amplified in the air gap!  For double glazing to be effective, you need a large air gap between the glass panes, with about 20cm between panes being the most effective.  Obviously this is hard to achieve in most homes, but what you can do is use glass with a higher density – laminated glass is the simplest (cheapest) option, and special “hush” glass is also available.

Interspace noise control is often considered, with people asking for acoustic insulation between rooms.  This will help, but often isn’t the best option.  If you have plumbing in the walls, then acoustic insulation won’t help much, but two layers of plasterboard or a layer of plywood and a layer of plasterboard will help a lot.  13mm plasterboard is also much better than 10mm plasterboard. 

You also need to consider airborne noise, and vibration – think treble and bass. 

To eliminate vibration, there are clips for attaching linings to structure that have rubber grommets, and again, like glass and walls, density of building materials helps.  The best solution we use to minimise noise transfer between floors, is to use solid concrete, or solid timber structure, rather than timber framing with particle board.

Interior space acoustics are often something you won’t consider or notice until you’re in a room that is particularly poorly performing.  It’s not until you’re in a poorly performing room and you can’t hear people talking that you really find out how important acoustics are – if they are working well, then we normally just take it for granted.

In architecture, there is a balancing act between aesthetics, thermal performance, and acoustics.  Thermal mass is often requested – this often relies upon the floor of a room being exposed concrete or tiles, which perform well thermally, and aesthetically, but are terrible acoustically.  If you combine a tiled floor with a lot of glazing to let the sun and light in, and plasterboard walls and ceilings, the room will perform terribly acoustically.

Carpeted rooms are relatively simple – the soft surface will absorb the noise rather than reflect it.

My solution for rooms where we want a lot of glazing, and a lot of thermal mass, is to use acoustic ceilings.  Our go-to material is timber, which we can get manufactured with holes in it, and install with absorbent acoustic blankets behind it – in my opinion this also looks great, as well as performs well.

In my opinion acoustic performance needs to be considered just as much as thermal performance if you want a building that is pleasurable to live in, especially as unlike heating, you can’t just turn a heat pump on to control acoustics…