Experimental evaluation of distortion in amplitude modulation techniques for parametric loudspeakers

Date
2020Version
Acceso abierto / Sarbide irekia
xmlui.dri2xhtml.METS-1.0.item-type
Artículo / Artikulua
Version
Versión publicada / Argitaratu den bertsioa
Project Identifier
ES/1PE/BIA2016-76957
Impact
|
10.3390/app10062070
Abstract
Parametric loudspeakers can generate a highly directional beam of sound, having applications in targeted audio delivery. Audible sound modulated into an ultrasonic carrier will get self-demodulated along the highly directive beam due to the non-linearity of air. This non-linear demodularization should be compensated to reduce audio distortion, different amplitude modulation techniques have been d ...
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Parametric loudspeakers can generate a highly directional beam of sound, having applications in targeted audio delivery. Audible sound modulated into an ultrasonic carrier will get self-demodulated along the highly directive beam due to the non-linearity of air. This non-linear demodularization should be compensated to reduce audio distortion, different amplitude modulation techniques have been developed during the last years. However, some studies are only theoretical whereas others do not analyze the audio distortion in depth. Here, we present a detailed experimental evaluation of the frequency response, harmonic distortion and intermodulation distortion for various amplitude modulation techniques applied with different indices of modulation. We used a simple method to measure the audible signal that prevents the saturation of the microphones when the high levels of the ultrasonic carrier are present. This work could be useful for selecting predistortion techniques and indices of modulation for regular parametric arrays. [--]
Subject
Publisher
MDPI
Published in
Applied Sciences, 2020, 10 (6), 2070
Departament
Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa. InaMat - Institute for Advanced Materials /
Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa. ISC - Institute of Smart Cities
Publisher version
Sponsorship
This work has been funded by the Spanish Ministry of Economy and Competitiveness through the R+D+I research project with reference BIA2016-76957-C3-2-R, and by the Government of Navarre through the Technology Transfer project 0011-1365-2019-000086.