Quiet Zone Design in Diffuse Fields Using Ultrasonic Transducers

Wen-Kung Tseng

Graduate Institute of Vehicle Engineering, National Changhua University of Education, Changhua.

DOI: 10.4236/jamp.2015.32036                

Abstract

This paper presents quiet zone design using ultrasonic transducers for local active control in pure tone diffuse fields. Most of researches in local active noise control used conventional loudspeakers for the secondary sources to produce quiet zones. Recently ultrasonic transducers have been used for the secondary sources to control the plane wave in active noise control. However there is no research related to active noise control in diffuse fields using ultrasonic transducers. Therefore this study uses ultrasonic transducers for the secondary sources to control the diffuse fields. The quiet zone produced using ultrasonic transducers in single tone diffuse fields has been analyzed through simulations in this work. The results showed that quiet zones created using ultrasonic transducers were larger than those created using conventional loudspeakers. This is due to the fact that the audible sound pressure produced by the ultrasonic transducers decays slowly with the distance. Therefore the secondary field created by an ultrasonic transducer could fit the primary field better and the larger zone of quiet could be obtained using the ultrasonic transducer. Also the audible sound produced by the ultrasonic transducers is directional; therefore the sound pressure amplification outside the quiet zones was lower. 

Keywords

Quiet Zone Design, Ultrasonic Transducers, Local Active Control, Diffuse Fields, Plane Wave

Conflicts of Interest

The authors declare no conflicts of interest.

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