08-22-2014, 02:49 PM
Sound reduction index
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Calculation of the sound reduction index R is based on test results obtained at different frequencies. The results are plotted against the reference curve between 100 Hz and 3150 Hz at 1/3-octave intervals. If the measurements are performed in situ (in a real building) the values are denoted R’. The standard test procedure is defined in EN ISO 140, where standard methods are given for both laboratory and field measurements.
The difference between laboratory and field values can be a significant number of dB depending on the const ruction details and workmanship.
If a partition consists of different kinds of elements – for example, a wall with windows and doors which have different sound transmission characteristics – the overall sound reduction index must be calculated.
The sound reduction index for holes and slits is nearly equal to 0 dB. The influence of holes and slits may therefore be important, for instance, at the connections between walls, at doors and windows without sealing strips, and at any necessary openings in partitions. If there is an acoustically absorbing material in the slits, it will give a higher sound reduction index for the slits.
Calculation of the sound reduction index R is based on test results obtained at different frequencies. The results are plotted against the reference curve between 100 Hz and 3150 Hz at 1/3-octave intervals. If the measurements are performed in situ (in a real building) the values are denoted R’. The standard test procedure is defined in EN ISO 140, where standard methods are given for both laboratory and field measurements.
The difference between laboratory and field values can be a significant number of dB depending on the const ruction details and workmanship.
If a partition consists of different kinds of elements – for example, a wall with windows and doors which have different sound transmission characteristics – the overall sound reduction index must be calculated.
The sound reduction index for holes and slits is nearly equal to 0 dB. The influence of holes and slits may therefore be important, for instance, at the connections between walls, at doors and windows without sealing strips, and at any necessary openings in partitions. If there is an acoustically absorbing material in the slits, it will give a higher sound reduction index for the slits.