A new impedance sensor for industrial applications
Abstract
Some years ago, the LAUM, together with the CTTM developed a new impedance sensor based on a controlled volume velocity source. The impedance of a measured system was easily and accurately obtained from 20 to 5000 Hz. Due to the low level of the generated volume velocity, this sensor is mainly devoted to laboratory studies (musical acoustics, porous material characterization...). For this measurement principle to be applied to engineering topics, a new device is conceived, using a recently developed electrodynamic transducer. In particular, leakages between its front and back sides should be reduced to a minimum, and mechanical resonances must be rejected out of the frequency range of interest. To illustrate the capabilities of this new impedance sensor, the characterization and tuning of a loudspeaker bass reflex enclosure is performed. The sensor measures the low frequency acoustic impedance of the enclosure seen from the loudspeaker location. The measured impedance is then compared with a lumped element model. The analysis of the impedance magnitude is used to cancel the acoustic resonances inside the volume and to check the correct tuning of the bass reflex system.
Origin | Publisher files allowed on an open archive |
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