Publication
A reliable sound source is essential in acoustic facilities, such as impedance tubes. However, conventional loudspeakers, regardless of their design, are prone to sound reflections, contrarily to theoretical matched sources. This can severely compromise the accuracy of the measurements, especially for nonlinear devices under test, where the unavoidably reflected harmonic components are likely to pollute the measurements. To be able to experimentally assess the performance of nonlinear systems, an ideal matched sound source capable of generating, without reflecting, a prescribed incident pressure is still missing. The corona discharge transducer consists of a membrane-less flow velocity source which is inherently transparent to sound. When backed with an anechoic termination (e.g. melamine foam wedge), one can generate sound while avoiding any reflection from the back, resulting in an actual matched source. An experimental prototype of such matched source has been designed and assessed in an impedance tube, focusing on linear frequency response and harmonic distortion analysis. Finally, the matched source is employed for assessing non-linear systems in impedance tube, and compared to conventional loudspeaker, to provide a practical demonstration of its capabilities under realistic conditions.