振動子アレイの動特性チューニングによる放射音波の偏向

抄録

In order to deflect the radiated sound waves by an array of sound sources, temporal phase differences between the adjacent sound sources are necessary. Usually, the sound can be deflected by electronically providing the phase-shifted driving signal to sound sources comprising the array. In this study, we propose a new method for deflecting sound emitted from a linear array of sound sources whose driving frequency, amplitude, and phase characteristics are all consistent. Instead of directly changing the phase of the driving signal, the dynamic characteristics of the vibration systems installed in front of the emitter are adjusted to cause a physically phase-shifted response. Such an indirect phase difference caused by the vibrator array achieves the deflection of the interfered sound waves. Firstly, numerical calculations are performed by assuming different natural frequencies to the vibrators composing an array so that the radiated sound could be deflected at angles of θ = 20°, 30°, 40°, 50°, and 60°. It was found that the desired deflection angle could be obtained under all conditions. Secondly, experiments were conducted to verify the numerical predictions. Thin resin plates with different elastic moduli were manufactured that mimicked vibrators. We confirmed that the sound wave could be deflected for all deflection angles at the sound source frequency of 4 kHz.