Acoustic Filter Elements
There are a number of different types of acoustic filter elements that are used in many different applications.
- Absorptive Duct
- Absorption within ducts is used to break up standing waves and attenuate high frequency noise such as flow generated noise.
- Expansion Chamber
- The expansion chamber can be considered as a simple low pass filter.
- Helmholtz Resonator
- It is effectively a mass on a spring (single degree of freedom system). The large volume is the spring and the volume of air in the neck is the mass.
- Porous Duct
- A number of different types of porous materials are used within engine air intake systems to break up standing waves that would exist in a solid wall construction.
- Quarter Wave Tube
- A resonator used most commonly on air intake systems to reduce resonance. Works over a narrow frequency range, i.e. used to attenuate a specific frequency.
- Side Branch Orifice
- The side branch orifice is an acoustic filter element and behaves as a high pass filter.
See also: Acoustic Impedance, Duct Acoustics, Expansion Chamber, Helmholtz Resonator, Insertion Loss, Quarter Wave Tube, Side Branch Orifice, Silencer.
Subjects: Architectural Acoustics Mechanical Engineering Noise & Vibration