Characterization of condenser microphones under different environmental conditions for accurate speed of sound measurements with acoustic resonators

Journal Article · Wed Jul 15 00:00:00 EDT 2009 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.3160295· OSTI ID:22053528

Guianvarc'h, Cecile; Pitre, Laurent ^[1]; Gavioso, Roberto M; Benedetto, Giuliana ^[2]; Bruneau, Michel ^[3]

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1. Laboratoire Commun de Metrologie LNE/Cnam, 61 rue du Landy, 93210 La Plaine Saint Denis (France)
2. Istituto Nazionale di Ricerca Metrologica, Strada delle Cacce 91, 10135 Turin (Italy)
3. Laboratoire d'Acoustique de l'Universite du Maine UMR CNRS 6613, av. Olivier Messiaen, 72085 Le Mans Cedex 9 (France)

Condenser microphones are more commonly used and have been extensively modeled and characterized in air at ambient temperature and static pressure. However, several applications of interest for metrology and physical acoustics require to use these transducers in significantly different environmental conditions. Particularly, the extremely accurate determination of the speed of sound in monoatomic gases, which is pursued for a determination of the Boltzmann constant k by an acoustic method, entails the use of condenser microphones mounted within a spherical cavity, over a wide range of static pressures, at the temperature of the triple point of water (273.16 K). To further increase the accuracy achievable in this application, the microphone frequency response and its acoustic input impedance need to be precisely determined over the same static pressure and temperature range. Few previous works examined the influence of static pressure, temperature, and gas composition on the microphone's sensitivity. In this work, the results of relative calibrations of 1/4 in. condenser microphones obtained using an electrostatic actuator technique are presented. The calibrations are performed in pure helium and argon gas at temperatures near 273 K and in the pressure range between 10 and 600 kPa. These experimental results are compared with the predictions of a realistic model available in the literature, finding a remarkable good agreement. The model provides an estimate of the acoustic impedance of 1/4 in. condenser microphones as a function of frequency and static pressure and is used to calculate the corresponding frequency perturbations induced on the normal modes of a spherical cavity when this is filled with helium or argon gas.

• OSTI ID: 22053528
• Journal Information: Review of Scientific Instruments, Vol. 80, Issue 7; Other Information: (c) 2009 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
ACOUSTICS
ACTUATORS
AIR
AMBIENT TEMPERATURE
ARGON
CALIBRATION
CAVITIES
DISTURBANCES
FREQUENCY DEPENDENCE
HELIUM
IMPEDANCE
PRESSURE RANGE KILO PA
RESONATORS
SENSITIVITY
SOUND WAVES
SPHERICAL CONFIGURATION
TEMPERATURE RANGE
TRANSDUCERS
WATER