Attenuation in ducts with 25 mm lining are indicated below:
Attenuation in ducts with 50 mm lining are indicated below:
- 1 in = 25.4 mm
- 1 ft = 0.3 m
- sound attenuation in unlined duct
Example - Sound Attenuation in Lined Duct
The sound attenuation in 610 x 610 mm lined duct is approximately 2.5 dB/m at frequency 250 Hz. The sound attenuation in 10 m duct can be calculated as
(10 m) (2.5 dB/m) = 25 dB
Room acoustics and acoustic properties, decibel A, B and C, Noise Rating (NR) curves, sound transmission, sound pressure, sound intensity and sound attenuation.
Noise is usually defined as unwanted sound - noise, noise generation, silencers and attenuation in HVAC systems.
The speed and attenuation of sound in moist air varies with sound frequency and air humidity.
Estimating sound attenuation where ducts splits to terminals.
Sound attenuation from main ducts to branch ducts.
Noise attenuation in duct elbows by reflected sound.
Sound transmission from ducts to surrounding rooms.
Noise attenuation in unlined sheet-metal ducts.