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Acoustic isolation vessel for measurement of the background noise in microphonesAn acoustic isolation vessel has been developed to measure the background noise in microphones. The test microphone is installed in an inner vessel, which is suspended within an outer vessel, and the intervening air space is evacuated to a high vacuum. An analytical expression for the transmission coefficient is derived, based on a five-media model, and compared to experiment. At an isolation vacuum of 5 x 10 exp -6 Torr the experimental transmission coefficient was found to be lower than -155 dB at frequencies ranging from 40 to 1200 Hz. Measurements of the A-weighted noise levels of commercial condenser microphones of four different sizes show good agreement with published values.
Document ID
19930068878
Document Type
Reprint (Version printed in journal)
Authors
Ngo, Kim C. T. (Old Dominion Univ. Norfolk, VA, United States)
Zuckerwar, Allan J. (NASA Langley Research Center Hampton, VA, United States)
Date Acquired
August 16, 2013
Publication Date
May 1, 1993
Publication Information
Publication: Acoustical Society of America, Journal
Volume: 93
Issue: 5
ISSN: 0001-4966
Subject Category
ACOUSTICS
Distribution Limits
Public
Copyright
Other