Record Display for the EPA National Library Catalog


Main Title Environmental effects on microphones of various constructions /
Author Hruska, Gale R.
Other Authors
Author Title of a Work
Magrab, Edward B.
Penzes, William B.
Publisher Dept. of Commerce, National Bureau of Standards : Reproduced by National Technical Information Service,
Year Published 1976
Report Number EPA/550-9-76-009; NBSIR-76-1090; NBS-2003110
Stock Number PB-255 505
OCLC Number 04398474
Subjects Microphone--Calibration
Additional Subjects Microphones ; Acoustic measurement ; Calibrating ; Electrets ; Ceramics ; Capacitors ; Sensitivity ; Humidity ; Temperature ; Environmental tests ; Stability ;
Internet Access
Description Access URL
Library Call Number Additional Info Location Last
ELBD ARCHIVE EPA 550-9-76-009 Received from HQ AWBERC Library/Cincinnati,OH 10/04/2023
ESAD  EPA 550-9-76-009 Region 10 Library/Seattle,WA 12/19/2018
NTIS  PB-255 505 Some EPA libraries have a fiche copy filed under the call number shown. 07/26/2022
Collation 24, A-8 pages : illustrations ; 28 cm
The pressure sensitivities of two 1/2-inch electret, two 1-inch ceramic, and two back-vented 1-inch condenser microphones were measured for numerous combinations of temperature, percentage relative humidity, and frequency. The two condenser microphones were calibrated by the reciprocity technique at each combination of temperature, relative humidity and frequency. The condenser microphones were then used as calibrated sources to determine the pressure sensitivities of the other microphones. Insert voltage techniques were used to eliminate the environmental effects on the electronics. It was found that the back-vented condenser microphones are insensitive to changes in relative humidity. At frequencies considerably below their resonance frequencies they exhibited only a very small change in sensitivity with temperature. At frequencies closer to the resonance frequency the temperature coefficient increases approximately fourfold. The temperature and humidity coefficient for the electret and ceramic microphones could not be determined due to the instability in their sensitivities which produced changes that were larger than those induced by the temperatures and humidities.
"NBSIR 76-1090." "EPA/550-9-76-009." "PB-255 505." "July 1976." Includes bibliographical references.