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arXiv · 2412.08409

A nonreciprocal and tunable active acoustic scatterer

Anis Maddi·Gaelle Poignand·Vassos Achilleos·Vincent Pagneux·Guillaume Penelet
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Abstract

A passive loudspeaker mounted in a duct acts as a reciprocal scatterer for plane waves impinging on either of its sides. However, the reciprocity can be broken by means of an asymmetric electroacoustic feedback which supplies to the loudspeaker a signal picked-up from a microphone facing only one of its sides. This simple modification offers new opportunities for the control and manipulation of sound waves. In this paper, we investigate the scattering features of a pair of such actively controlled loudspeakers connected by means of a short and narrow duct. The theoretical and experimental results demonstrate that by tuning the feedback loops, the system exhibits several exotic effects, which include an asymmetric reflectionless configuration with one-way transmission or absorption, a directional amplifier with an isolation of 42 dB, and a quasi CPA-lasing configuration. All of these effects were achieved using a single setup in the subwavelength regime, highlighting the versatility of such an asymmetrically active scatterer.

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Anis Maddi, Gaelle Poignand, Vassos Achilleos, Vincent Pagneux, Guillaume Penelet. 2024-12-11. A nonreciprocal and tunable active acoustic scatterer. https://arxiv.org/abs/2412.08409

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