A self-silenced sound beam
Source: Acoustical Physics, Volume 56, Number 5, September 2010 , pp. 637-639(3)
Publisher: MAIK Nauka/Interperiodica
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.
Document Type: Research article
Publication date: 2010-09-01