A Directional Audible Sound System using Ultrasonic Transducers

Wen-Kung Tseng

doi:10.14569/ijarai.2015.040903

Abstract

In general the audible sound has the characteristics of spreading, however the ultrasound is directional. This study used amplitude-modulating technique for an array of 8 ultrasonic transducers to produce directional audible sound beam. In this study sound field distribution for the directional audible sound beam has been investigated. The effect of different weightings varied with different frequency for the transducers on the directivity of the sound beam has also been evaluated. An H (infinity) optimization method was used to calculate the optimal weightings of the transducers for better directivity of the sound beam. Different optimal weightings also added to the carrier and sideband frequencies to control the difference frequency’s beamwidth and sidelobe amplitude. The results showed that the beam width can be controlled and good directivity of the sound beam can be obtained by using the H_8 optimization method.

Highlights

IntroductionThe highly directional audible sound has been investigated for a few years
The simulation results for the directivity of the audible sound beam created by using the optimization method are presented, and compared to those obtained by using Chebyshev weighting method [2]
In this paper the optimization method has been proposed for designing directional audible sound beam

Summary

Introduction

The highly directional audible sound has been investigated for a few years. The audible sound has the characteristics of spreading, the ultrasound is directional. The performance in the ultrasound systems and their beamforming has been studied. Beamforming is the concept of forming directional beams. Previous study [1] has discussed that two plane waves of different ultrasonic frequencies could generate the directional audible sound due to acoustical nonlinearity. There are mainly two new waves, one of which has a frequency equal to the decrease of the original two frequencies and the other equal to the difference frequency

Methods

Results

Conclusion