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|Type:||Artigo de evento|
|Title:||The Development Of A Calibrated Acoustic Actuator Based On The Two-microphone Technique|
|Abstract:||This paper presents the realization of a calibrated acoustic actuator that represents an improvement to the commercially available actuators that use a driver loudspeaker connected to a tube. The usual calibration of this device is made using one microphone under the assumption that the environment influence is negligible. Previous work demonstrated that under special conditions (high impedance medium), this simplifying assumption is not valid and volume acceleration is not accurately measured. The present article investigates an improved calibration technique that uses two microphones. As only plane waves will propagate in the tube (of small diameter) in the frequency range of interest, the two-microphone technique allows the calculation of the amplitudes of the waves going inward and outward the tube mouth. The focus of the analysis is centered on the measurement of the volume acceleration, which is needed in the acoustic modal analysis, and on the active acoustic power, necessary for experimental SEA. The volume acceleration measurement was first validated in an anechoic chamber and the experimental acoustic modal analysis of a rectangular shallow cavity, which has an analytical solution, proved the accuracy of the actuator in a medium of relatively high impedance. The measurement of the acoustic active power was made in an anechoic chamber and it is shown that the two-microphone technique faces large problems in this case. An alternative technique is proposed for the measurement of the acoustic active power in media approaching a free-field, and a different device configuration is proposed for future work.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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