Design
D - 26
(6)Converting to overall A characteristics from octave band levels
If the calculated value for each band in the above table is adjusted by the conversion factors in the above
table, the A characteristic is obtained. These values are then combined in order of magnitude, using the
following calculation diagram to obtain the overall A characteristic.
<Calculation example >
From the frequency analysis table (operating sound for each octave band central frequency) the octave band
levels (dB) are obtained. These values are corrected with the A characteristic correction factor to obtain the A
characteristic. The following is a calculation for operating sound level.
These A characteristic values are combined one by one in order of magnitude. (same as combining operating sound)
(7) Designing sound-proofing countermeasures
<Calculation example>
In the installation of the figure on the right, a scheme for
sound-proofing operation sound with respect to the reception
point is required.
Firstly, the operating sound of the outdoor unit is read
according to frequency. This information is input into Table 1,
the sound-proofing calculation sheet, and the sound
attenuation and amplification for the installation is calculated.
he overall A characteristic is calculated to be 60.95dB(A).
Sound source
Outdoor unit
House
Reception
point
Noise barrier
Outdoor unit
Penthouse
Penthouse
Reflected
sound
House
Reception point
6. Sound-proofing measures
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