Stiffness control of low frequency acoustic transmission through the walls of rectangular ducts
Abstract
An investigation is reported here on the use of "stiffness control" to reduce low frequency acoustic "breakout" through the walls of rectangular air-moving ducts; in this, attempts are made to increase the fundamental transverse resonance frequency of the duct walls (by using materials with a high stiffness/mass ratio) so that the capacitive (stiffness) controlled nature of the wall impedance below this frequency may be exploited to raise the wall transmission loss and remove low frequency resonances. Some degree of success is achieved in this, and the results appear encouraging. As a necessary part of the work, the nature of the acoustic/structural wave combinations is explored in more detail than hitherto, and a simplified low frequency approximate method of determining the transmission loss of ducts is also given.
- Publication:
-
Journal of Sound Vibration
- Pub Date:
- February 1981
- DOI:
- 10.1016/0022-460X(81)90304-7
- Bibcode:
- 1981JSV....74..351C
- Keywords:
-
- Acoustic Ducts;
- Acoustic Impedance;
- Acoustic Propagation;
- Stiffness;
- Transmission Loss;
- Walls;
- Low Frequencies;
- Metal Sheets;
- Resonant Frequencies;
- Rigid Structures;
- Sandwich Structures;
- Sound Transmission;
- Wave Equations;
- Acoustics