A self-silenced sound beam |
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Authors: | C M Hedberg K C E Haller T Kamakura |
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Institution: | 1. Blekinge Institute of Technology, School of Engineering, 371 79, Karlskrona, Sweden 2. Department of Electronic Engineering, University of Electro-Communications, 1-5-1, Choufugaoka, Choufu-shi, Tokyo, 182-8585, Japan
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Abstract: | Parametric loudspeakers are transmitting two high power ultrasound frequencies. During propagation through the air, nonlinear interaction creates a narrow sound beam at the difference frequency, similar to a light beam from a torch. In this work is added the physical phenomenon of propagation cancellation, leaving a limited region within which the sound can be heard—a 1 meter long cylinder with diameter 8 cm. It is equivalent to a torch which would only illuminate objects within 1 meter. The concept is demonstrated both in simulation and in experiment. |
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