Before you start collecting all those egg boxes, we wanted to provide an insight into a few soundproofing fundamentals that ensure you do not start causing yourself a bigger headache than you had before!
Firstly let’s clear up one misconception. Sound attenuation is not the same as sound absorption and you could be left very disappointed if you do not apply the correct mitigation method.
Sound attenuation is the measure of energy loss in the form of decibels through a partition or barrier erected between a noise source and receptor i.e stopping sound from emitting into and out of a space.
Sound absorption is when a material dissipates sound energy (measured as an absorption coefficient) minimising its reflection to ensure resonance does not occur.
Effectively anything heavy and dense will considerably reduce sound, even the troublesome low bass frequencies. This approach will best control airborne noise such as speech but will be less effective against impact noise (structural borne transmission) which we will touch on shortly.
It is essential that whilst installing high density mass, additional materials are used in conjunction that have a supple membrane such as rubber or mass loaded vinyl.
The dampening element must always be sandwiched between the heavyweight mass materials chosen allowing sound waves to move through each substance at different speeds creating friction and thus transferring movement into thermal energy or heat, and therefore attenuating noise to a greater extent.
Any mass barrier installed should be independent to the existing building envelope to ensure structure borne transmission does not occur. This is when sound waves pass through structural components of a building, generating various tones and noise issues at a receptor position.
The isolation design varies, depending on environmental conditions, application and the optimal specific frequency that needs to be attenuated. The solution can range from simple resilient isolation bars to specifically tuned rubber compound or steel spring mounts.
As discussed above sound attenuation and sound absorption are very different, but the latter can be a contributing factor to noise disturbance. Improving sound absorption is therefore one of the principles of improving attenuation. Where a noise source is positioned within a space with reflective surfaces, sound will reverabete causing an amplification to occur. This generates additional air and structure borne transmission.
Whilst assisting with attenuation, it also improves the speech intelligibility of a space forming the perfect listening environments found in recording studios and sound stages.
Reducing the reverberation time of a space is a relatively simple process as it is a case of disrupting and absorbing a wave form within a space. Treatment can be as simple as using those egg boxes you’ve been collecting to the installation of acoustic foam blocks in specific locations.
It’s important to remember every soundproofing scenario is different, whether that’s due to the sound source or just the receptors requirements, therefore the attenuation design should be specifically adapted to each job to see optimal performance.
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