Spectral peak noise reduction with frequency modulated carrier wave for parametric loudspeaker

摘要

In the conventional modulation method with amplitude modulation (AM) in a parametric loudspeaker, a carrier frequency of an AM wave is set at a resonance frequency of ultrasonic elements to intensely emit the AM wave. In the parametric loudspeaker, it is known that causes fatigue failure of ultrasonic elements due to supply high voltage to the ultrasonic element. Spectral peak noise is generated in using the parametric loudspeaker with fatigue failure of ultrasonic elements. Then, the power of the spectral peak noise depends on the carrier frequency. Therefore, we propose the spectral peak noise reduction method with the frequency modulated carrier wave. The proposed method can reduce the spectral peak noise. From evaluation experiments, we confirmed that the proposed method can reduce the spectral peak noise and the demodulated sound with the proposed method is similar to one with the conventional method.