Article
Measurement of transmission parameters of porous sound-absorbing materials. Part 1. Measurement Techniques in Terms of the Electrical Analogues
Instrument Review
(1965)
Abstract
Adoption ofthe novel "pseudo-impedance " artifice is partly responsible for complicating the measurements ; although a little tedious to the user it makes measurements possible over a wide frequency-range without involving any "tuning" operation, so that the sample of material can be held in a short, rigid tube of fixed length. The electrical analogues that form the basis of this part of the paper are justified by the findings of Part 2 where it will be shown that sound pressure is attenuated in pas sing into the thickness of the test-material in much the same way that voltage is attenuated in travelling along an electrical transmission-line . The final stages of Part 2 describe how the primary acoustical transmission constant s are derived ; Part 1 carries the analysis up to this same point but in terms of the electrical analogue. Occasionally it will be necessary to anticipate later findings but only to keep the discussion within proper bounds and in general this part will treat the behaviour of transmission lines by direct analogy as follows : (b) a terminal load equal to Zo, the characteristic trans- mission impedance of the line ; Alternating sound pressure Alternating volume-flow of air Acoustical impedance Alternating p.d. Alternating current. Electrical impedance
Keywords
- Acoustic,
- Measurement
Disciplines
Publication Date
Spring May, 1965
Citation Information
Edmund Ramsay Wigan. "Measurement of transmission parameters of porous sound-absorbing materials. Part 1. Measurement Techniques in Terms of the Electrical Analogues" Instrument Review (1965) p. 183 - 203 Available at: http://works.bepress.com/edmund-wigan/24/