Omnidirectional Parametric Loudspeaker
The research team of La Salle Acoustics has designed an omnidirectional source of sound (in other words, a loudspeaker that is able to radiate sound in the 360º) that is built with parametric loudspeakers.
An initial prototype, the omnidirectional parametric loudspeaker (OPL), consisting of a sphere with hundreds of ultrasonic transducers placed on it has been constructed. The OPL emits audible sound thanks to the parametric acoustic array phenomenon, and the close proximity and the large number of transducers results in the generation of a highly omnidirectional sound field.
Compared to a conventional dodecahedron loudspeaker, the OPL prototype has performed better specially for frequencies higher than 500 Hz, its main drawback being the difficulty to generate intense pressure levels at low frequencies. From a practical point of view, the OPL prototype is by far lighter and handier than a conventional loudspeaker (it weights less than 500gr, whereas a standard dodecahedron weights about 10Kg).
The prototype is protected by patent and the research results have been published in the Journal of Acoustical Society of America (J. Acoust. Soc. Am. Volume 134, Issue 3, pp. 1899-1907).