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Acoustics - Basic Guide to Acoustic Terminology

 

Sound Reduction

Sound Reduction - May also be termed sound attenuation or sound insulation. Stated in decibels it is the ratio of the amount of sound energy incident upon a partition and the proportion of that energy which passes through the partition.

 

red Decibel: 'a logarithmic scale applied to acoustic units such as sound pressure, sound intensity and sound power.'

It is also used to express sound reduction or sound insulation when the result is stated as a "decibel reduction". Audible sound ranges from the threshold of hearing at 0dB to the pain threshold at around 130-140dB.

 

red dBA A-weighting: This is a filter process.

Human hearing is less sensitive at very low and very high frequencies. To account for this, the noise is ‘weighted’ to provide results which conform approximately to the response of the human ear. Denoted as dB

 

red Rw Weighted Sound Reduction Index: R values are measured in tests in octave or 1/3rd octave bands covering the range 100Hz to 3150Hz (tests actually cover a wider range).

The resultant curve is adjusted so that any shortfall of the actual measurements below the standard curve, averaged over all the octave or 1/3 octave bands is not greater than 2dB. The resultant value of the curve at 500Hz is the Rw.