Construction of a new Omnidirectional Parametric Loudspeaker prototype

Omnidirectional loudspeakers are needed to perform a large variety of tests in acoustics, such as the measurement of the airborne sound insulation in buildings, or the reverberation time of a room. Researchers of the GTM (see publication below) have developed a new kind of sound source that uses ultrasound transducers instead of the standard speaker drivers arranged in a dodecahedral loudspeaker. Hundreds of these transducers are set on a sphere, each one emitting an ultrasonic carrier wave modulated by an audible signal. Thanks to nonlinear propagation, the air itself demodulates the signal bringing it back to the audible range. In this way, audible sound waves are emitted in all directions, obtaining what we termed as Omnidirectional Parametric Loudspeaker (OPL).

The construction of this prototype as well as some preliminary results have recently been published in the international journal Sensors. Details of the new OPL prototype can be found in this open access publication. The OPL improves the omnidirectionality of conventional dodecahedral loudspeakers at high frequencies. This work has resulted from the collaboration between researchers of the acoustics and signal processing areas of the GTM.

Link:  https://doi.org/10.3390/s18124317

Marc Arnela, Oriol Guasch, Patricia Sánchez-Martín, Joan Camps, Rosa Ma Alsina-Pagès and Carme Martínez-Suquía (2018), “Construction of an Omnidirectional Parametric Loudspeaker consisting in a Spherical Distribution of Ultrasound Transducers“, Sensors, 18 (12).

This work was supported by the BUILT2SPEC project, which received funding from the European Union’s Horizon 2020 Research and Innovation Program under Grant No. 637221. Acknowledgment is also given to the Universitat Ramon Llull internal project 2017-URL-Proj-015.