Noise Attenuation by Changing Duct Area

Sound attenuation when changing duct areas or dimensions:

dL = 10 log( ( 1 + A₁ / A₂ )² / 4 (A₁ / A₂) )                                                                (1)

where

dL = noise attenuation (dB)

A₁ = inlet area (m²)

A₂ = outlet area (m²)

Note! - valid only for sharp changes.

Example - Attenuation when changing the size of a duct

The attenuation of noise when the ratio between area before and after A₁ / A₂ = 5 - can be calculated as

dL = 10 log( ( 1 + 5 )² / 4 (5))

    = 2.5 dB

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Citation

This page can be cited as

• Engineering ToolBox, (2008). Noise Attenuation by Changing Duct Area. [online] Available at: https://www.engineeringtoolbox.com/duct-area-change-noise-attenuation-d_1408.html [Accessed Day Mo. Year].

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