Stop That Noise! – Sound Deadening for Car Audio Applications

Stop That Noise!

Sound Deadening For Car Audio Applications

A car offers many challenges to the music lover. Apart from the rubbish equipment fitted as standard and passed off as “in car entertainment” there are challenges associated with the afterthought positioning of the speakers to contend with too. However, one of the most basic of improvements you can make does not carry a huge financial overhead but will make things sound better and is absolutely essential before you upgrade your speakers. The dark art to which I refer is sound deadening. Cars are made from flimsy metal panels which flex and oscillate when mechanical movement is induced. A speaker moves air and is made to oscillate by a conversion of electronic signal input into mechanical movement. The common denominator is that both result in air being moved about. The problem with car body panels moving air is that this directly compromises the same air being moved by the speakers.

It is necessary to get your head around how sound is heard in order to gain a full understanding of this. There is a lot of very good information on this on the internet but basically, ears collect movement in air and concentrate it, sending down tubes on either side of your head which are lined with minute hairs which are blown about as a result. the brain interprets the “blowing about” into perceived sound – Wonderful aint it? This is of course a very basic description for those who don’t have time to find out all of the ins and outs but it  is more or less the case. Imagine what happens when turbulence is introduced into the air the ear is collecting? The brain is very good at separating different noises out but has its limitations and disturbances that are similar in frequency to those you want to hear will affect the amount and quality of the sound you are trying to hear. A speaker cone moves in and out at varying speeds (frequencies) to project sound into the air and towards the listeners ears. This mechanical movement can be affected or distorted by air blowing in the opposite direction. Can we eliminate the affect of wobbly car panels and air disturbance in a car? – I would say this is not practically possible however, it can be made much, much better.

The first step to take is to make the wobbly panels a little more rigid by applying  a flexible, mechanically absorbent material. Such materials exist in ready supply by way of Skinz sound deadening. This is a flat sheet of layered materials with layers of bitumen in between them. as the bitumen never becomes solid, any vibrations in the panels to which it is affixed will be literally dampened down to almost nothing. It is very effective and will cut down the noise inside a vehicle radically. As a minimum the doors where speakers are to be fitted require this treatment. If you drive an inherently noisy vehicle such as a LandRover Defender or panel van for instance, then huge additional noise attenuation can be achieved by treating as many panels as can be reached including roof and floor. If you are new to this, it may sound a bit whacky, but believe me, it is a very common practice these days!

As you can see from the image above, Skinz has a shiny relatively flat surface and although it is very good at deadening “lively” panels, it offers a reasonably reflective surface which will reflect sound generated from the rear of a speaker mounted against it. Sometimes called back waves, these too can cause unwanted air to distort the speaker cone or at least suppress free movement so another solution was developed. Called  Wave diffuser, this is a thick open cell foam with a similar profile to the inside of an egg box. Being made of fairly soft foam it offers additional damping but the complex shape of its surface also scatters any back waves so they do not get reflected back to the speaker.

For those looking for further damping, employing Skinz panel liner could be just the ticket. This is available in two thicknesses, 6mm and 10mm. This is a flat self-adhesive foam and can be used in conjunction with Skinz sound deadening to further attenuate unwanted noise in the vehicle.

All of these products are used routinely by your local FOUR MASTER who is also expert at removing door panels, floor coverings and roof linings without causing damage so as always, we urge you to leave the job to them. If you purchase a pair of speakers from a FOUR MASTER he will always recommend adding sound treatment as part of the job. Your speakers will work far better in treated mounting areas.

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