Scientific Fact: Weighted Sound Insulation Rating

Weighted sound insulation level refers to the sound insulation level measured through a weighting network. Under the condition that the frequency spectrum and sound level of the sound source room are fixed, the sound insulation level measured in the receiving room is used to evaluate the sound insulation performance of the partition or component.

The weighted sound insulation level is determined by comparing a standard curve with the sound insulation frequency characteristics curve of the component. The standard curve takes into account the auditory characteristics of the human ear, meaning that the ear is less sensitive to high-frequency sounds than to low-frequency sounds. Additionally, it considers that typically, sound-insulating components have lower insulation at low frequencies and higher insulation at high frequencies. The standard curve is a broken line that varies with frequency. Although the sound insulation levels at different frequencies are different on this standard curve, the perceived sound insulation effect is the same, similar to the equal-loudness contour, effectively making it an equal sound insulation effect curve.

The steps to determine the weighted sound reduction index are as follows:

First, plot the sound insulation levels of the soundproofing components across different frequency bands on a graph with the sound insulation level on the vertical axis and frequency on the horizontal axis, and connect them to form a sound insulation frequency characteristic curve. Then, draw the standard curves for evaluating weighted sound insulation levels on a transparent sheet with the same coordinate scales (or copy the standard curves onto transparent polyester film), place the transparent standard curve graph over the sound insulation frequency characteristic curve graph of the components, align the frequency coordinates of both graphs, and move them vertically up and down until they meet the following two conditions.

The 1/3 octave frequency characteristic curve for sound insulation should meet:

The total sum of dB values for adverse deviations below the standard curve in all bands does not exceed 32dB.

(2) The sound insulation level of any frequency band in the sound insulation frequency characteristic curve should not exceed an adverse deviation of more than 8 dB below the standard curve.

The 1/1 octave bandwidth sound insulation frequency characteristic curve should meet:

(1) The total sum of dBs below the standard curve for all bands does not exceed 10dB.

(2) The sound insulation level of any frequency band in the sound insulation frequency characteristic curve should not exceed a negative deviation of more than 5 dB below the standard curve.

Then, draw a vertical line upward from 500Hz to intersect with the standard curve, and draw a horizontal line from the intersection point to intersect with the vertical axis of the sound insulation frequency characteristic curve diagram. The dB value at the intersection point is the calculated weighted sound insulation level RW.

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