Abstract : Demand for calibration at infrasonic frequencies has emerged in response to earth monitoring problems. The primary standard for sound pressure is defined through the reciprocity calibration method specified in the International Electrotechnical Commission (IEC) Standard 61094-2:2009. This method is based on the use of closed couplers and is routinely applied by the National Metrology Institutes for a large frequency range; however, infrasonic frequencies below 2 Hz have not been explored until recently. The acoustic transfer admittance of the coupler, including the heat conduction effects of the fluid, must be modelled precisely to obtain accurate microphone sensitivity. IEC 61094-2:2009 provides two standardised solutions for the correction of heat conduction. However, researchers have noted significant deviations between these corrections at low frequencies in plane wave couplers, indicating that one or both techniques incorrectly calculate the influence of heat conduction. In this paper, the limitations of the standardised formulations at infrasonic frequencies are identified and two alternative solutions are proposed. An experiment is also reported, which highlights the discussed limitations of the standardised formulations for acoustic transfer admittance, while also demonstrating the validity of the proposed alternative formulations at frequencies down to 0.04 Hz.
https://hal-univ-lemans.archives-ouvertes.fr/hal-02460960 Contributeur : Stéphane DurandConnectez-vous pour contacter le contributeur Soumis le : mardi 23 novembre 2021 - 12:11:48 Dernière modification le : mardi 8 mars 2022 - 16:34:02 Archivage à long terme le : : jeudi 24 février 2022 - 19:31:43
P. Vincent, D. Rodrigues, F. Larsonnier, Cécile Guianvarc'H, Stéphane Durand. Acoustic transfer admittance of cylindrical cavities in infrasonic frequency range. Metrologia, IOP Publishing, 2019, 56 (1), pp.015003. ⟨10.1088/1681-7575/aaee28⟩. ⟨hal-02460960⟩