Acoustic RoomTreatment as Opposed to Soundproofing

Firstly can I dismiss a common myth Acoustic foam will not soundproof a room. Soundproofing often referred to as isolating is a totally different to acoustically treating a room with acoustic foam, soundproofing is stopping sound traveling from one room to another; acoustically treating a room is controlling the sound response within a room.

Acoustic foam is one product used in the acoustic treatment of a room and is done by the placement of products which absorb frequencies and allow you to control the ‘liveness‘ of a room. The way in which acoustic foam does this by helping to reduce  reverberation, echo and standing waves within the room. Thus defining and tightening up the rooms response to sound waves and making the room much more suited to the recording and performing of music,  also to where the listening of music is important i.e in mixing rooms will also benefit with acoustic foam treatment, acoustic foam is now often used in home cinemas for exactly the same reasons.

As stated earlier acoustic foam will do little to help with soundproofing or the isolation of sound. In order to actually soundproof you need to de couple the room this means you must make a gap between the room and the outside / adjoining room, this is where “a room within a room” (rwar) is needed this is a method of isolating sound, as most sound transfer from a room to the outside / adjoining rooms occurs through mechanical means. For example the sound passes through objects as vibration and goes directly through the brick, woodwork and other solid structural elements. When it meets with an element such as a wall, ceiling, floor or window, which acts as a sounding board, the vibration is amplified and heard in the second space. A mechanical transmission is much faster, more efficient and may be more readily amplified than an airborne transmission of the same initial strength.

Another aspect of using acoustic foam is that it can also be overused  if too much is installed, for example some of the natural sounds in traditional recordings can be lost, live rooms need some colour to bring out the sounds of instruments. This is why we never treat a room with total acoustic foam. It is best to work using percentages. Nearly every room is different and it is best to start with some acoustic foam paneling and add more if needed until you are entirely happy with the sound within the room. This is a  simple yet effective way of getting the results you want.

The physical structure of acoustic foam can be described using five determining properties that make it best suited to its purpose the combination of the cell structure the air permeability, density resilience and hardness acoustic foam is specifically formulated to perfect these qualities for sound absorption applications and this differentiates it from any other types of foam. The use of carpets duvets upholstery or egg box packaging foam may well help with some high end frequencies they are far from an ideal solution. If you were to do a handclap test and think your room is now well treated as the room sound dead you may have absorbed some high frequency however the mids and lows will have changed little and this will come out on the recording.

Many people are selling standard upholstery and packaging foam products under the guise of acoustic foam to be sure you are getting acoustic grade foam Please look for the foams NRC values to check if it has been formulated specifically for acoustic applications before using it and if the foam looks to be cheap eggbox convoluted packaging foam it may well be just that.

Comfortex Acoustics – Acoustic Foam Products Supplied Direct From The Manufacturer