Title :
Measurement of thermal noise in condenser microphones and associated preamplifier in a vacuum-isolation vessel
Author :
Ngo, Kim Chi T ; Zuckerwar, Allan J.
Author_Institution :
Dept. of Electr. & Comput. Eng., Old Dominion Univ., Norfolk, VA, USA
Abstract :
The electrical noise generated by thermal agitation of the air molecules impinging upon the membrane of a condenser microphone and from its associated preamplifier has been studied analytically and experimentally over a wide bandwidth. These background noise levels constitute one of the most important specifications of a microphone, for they determine the lowest sound pressure than can be detected. Therefore, a novel method for measuring the thermal agitation noise within a bandwidth of 1-25600 Hz has been developed. It has been found experimentally that there is a 1/f noise source in the membrane of the microphone. Measurements of sound propagation into the isolation vessel as a function of vacuum at different frequencies are compared to theory
Keywords :
electric noise measurement; microphones; preamplifiers; thermal noise; 1 to 25600 Hz; 1/f noise; acoustical isolation; condenser microphones; electrical noise; membrane; preamplifier; thermal agitation noise; thermal noise measurement; vacuum-isolation vessel; Acoustic noise; Acoustic propagation; Background noise; Bandwidth; Biomembranes; Frequency measurement; Microphones; Noise generators; Noise measurement; Preamplifiers;
Conference_Titel :
Southeastcon '91., IEEE Proceedings of
Conference_Location :
Williamsburg, VA
Print_ISBN :
0-7803-0033-5
DOI :
10.1109/SECON.1991.147808
