School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore.
IEEE Trans Ultrason Ferroelectr Freq Control. 2011 Feb;58(2):437-50. doi: 10.1109/TUFFC.2011.1821.
In the past two decades, the majority of research on the parametric loudspeaker has concentrated on the nonlinear modeling of acoustic propagation and pre-processing techniques to reduce nonlinear distortion in sound reproduction. There are, however, very few studies on directivity control of the parametric loudspeaker. In this paper, we propose an equivalent circular Gaussian source array that approximates the directivity characteristics of the linear ultrasonic transducer array. By using this approximation, the directivity of the sound beam from the parametric loudspeaker can be predicted by the product directivity principle. New theoretical results, which are verified through measurements, are presented to show the effectiveness of the delay-and-sum beamsteering structure for the parametric loudspeaker. Unlike the conventional loudspeaker array, where the spacing between array elements must be less than half the wavelength to avoid spatial aliasing, the parametric loudspeaker can take advantage of grating lobe elimination to extend the spacing of ultrasonic transducer array to more than 1.5 wavelengths in a typical application.
在过去的二十年中，大多数关于参量扬声器的研究都集中在声传播的非线性建模和预失真技术上，以减少声音重放中的非线性失真。然而，关于参量扬声器指向性控制的研究却很少。本文提出了一种等效的圆形高斯声源阵列，该阵列可以近似线性超声换能器阵列的指向性特征。通过使用这种近似，参量扬声器的声束指向性可以通过乘积指向性原理来预测。本文提出了新的理论结果，并通过测量进行了验证，结果表明延迟求和波束控制结构对于参量扬声器是有效的。与传统扬声器阵列不同，为了避免空间混叠，阵列单元之间的间距必须小于半波长，而参量扬声器可以利用栅瓣消除来扩展超声换能器阵列的间距，使其在典型应用中超过 1.5 个波长。
