# Passive control: duct silencers

The noise from heating installations of large residential areas is radiated through the chimneys. This noise consists of large low-frequency tones within a wideband noise. The low-frequency tones can be attenuated by large duct silencers.

Attenuation of low-frequency noise through the chimney of a heating installation at 70 % (left) or 100 % (right) of its nominal power