08-22-2014, 02:56 PM
It is important to choose a suitable material and to make sure that is not bypassed with rigid bridges such as fixings and pipes.
Air paths, including those due to shrinkage, must be avoided; porous materials and gaps at joints in the structure must be sealed.
Resonances must also be avoided; these may occur if some part of the structure (such as dry lining) vibrates strongly at a particular sound frequency (pitch) and transmits more energy at this pitch.
Impact sound insulation is calculated from measurements of the sound pressure level produced by the standardised hammer method. The results are presented as a curve between 50 – 5000 Hz.
When calculating a single-number quantity L n,W or L’n,W the levels for the 16 frequencies are compared to the standard curve in a similar manner to the calculation of the sound reduction index. The only difference is that the deviation between the measured curve and the standard curve is in this case above the standard curve. Ln is measured in the lab whilst L’n is measured in the field. For both Ln and L’n low numerical values mean good impact sound insulation.
Also for impact sound insulation, two spectrum adoption terms Ci,100-2500 and Ci,50-2500 are needed in case of a floor with wooden beams. The difference between the results of laboratory and field measurement is caused by the flanking phenomena in a building. In a real building, sound transfers not only through a structure being designed – for example, a floor – but also via connecting structures adjacent to the floor.
Air paths, including those due to shrinkage, must be avoided; porous materials and gaps at joints in the structure must be sealed.
Resonances must also be avoided; these may occur if some part of the structure (such as dry lining) vibrates strongly at a particular sound frequency (pitch) and transmits more energy at this pitch.
Impact sound insulation is calculated from measurements of the sound pressure level produced by the standardised hammer method. The results are presented as a curve between 50 – 5000 Hz.
When calculating a single-number quantity L n,W or L’n,W the levels for the 16 frequencies are compared to the standard curve in a similar manner to the calculation of the sound reduction index. The only difference is that the deviation between the measured curve and the standard curve is in this case above the standard curve. Ln is measured in the lab whilst L’n is measured in the field. For both Ln and L’n low numerical values mean good impact sound insulation.
Also for impact sound insulation, two spectrum adoption terms Ci,100-2500 and Ci,50-2500 are needed in case of a floor with wooden beams. The difference between the results of laboratory and field measurement is caused by the flanking phenomena in a building. In a real building, sound transfers not only through a structure being designed – for example, a floor – but also via connecting structures adjacent to the floor.