An acoustic filter element used to reduce sound pressure levels inside a duct.
There are three types of silencer:
- Absoptive silencer - uses absorptive material to reduce noise levels
- Reactive silencer - uses expansion and reactive acoustic filters to reduce noise levels
- Active silencer - use active noise cancellation that adds noise using a loudspeaker to cancel out noise
A type of absorption silencer with a single perforated tube surrounded by sound-absorbing fibre. This results in a very low back pressure silencer, but at the same time only attenuates higher frequency noise.