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Sound Transmission through Duct Walls
Estimating sound transmission from ducts to surrounding rooms
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Sound transmitted from the inside of a duct to the surrounding room can be expressed as:
Lp = Lw - TL - 10 log( A F / 4 Ad ) (1)
where
Lp = sound pressure in room (dB)
Lw = sound power level in the duct (dB)
TL = transmission loss through duct wall (dB)
A = room absorption (m2 sabine)
F = cross section area of duct (m2)
Ad = surface area of duct (m2)
Transmission loss through duct walls are indicated in the table below:
| Attenuation - TL - (dB) | ||||
| Duct sheet thickness (mm) |
Frequency (Hz) | |||
| 125 | 250 | 500 | 1000 | |
| 1.25 | 17 | 22 | 25 | 29 |
| 1.0 | 15 | 20 | 23 | 27 |
| 0.75 | 14 | 19 | 22 | 26 |
| 0.65 | 12 | 17 | 20 | 24 |
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Related Topics
- Acoustics - Room acoustics, acoustic properties - decibel A, B and C - Noise Rating (NR) curves, sound transmission, sound pressure, sound intensity, attenuation and more ..
- Noise and Attenuation - Noise is usually defined as unwanted sound - noise, noise generation, silencers and attenuation in HVAC systems
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