Research on the cancellation of background reflected sound field based on parametric array loudspeaker

The adaptive active control of sound field adopts the reference sensor as the feedforward processing, but the effect is not ideal and some environmental factors are difficult to meet this condition. In this paper, the problem of active control of the reflected sound field of a finite volume target is studied. The incident sound wave on the target surface is used as the reference source, the high directivity parametric array loudspeaker is used as the secondary sound source, Using the target reflection response function to modulate the emission signal of the secondary sound source, the reflected sound of the target itself is cancelled. A real-time processing controller is developed to perform the functions of incident wave acquisition, transfer function storage and loading, and real time demodulating of parametric array. Two typical targets are tested. For the indoor wall, the echo intensity of all frequency bands is reduced 6-15dB. For the outdoor metal cylinder (diameter 0.4m, height 2.5m), the echo intensity is reduced 6-9dB, and the adaptability of the transfer function to different signals is verified. The parametric loudspeaker has a constant narrow directivity in a wide frequency band. This method can be used in a variety of audio environments.