Investigations in acoustics, electroacoustics and signal processing

我的目标是支持音频工程界在声学、电声学、测量工具和信号处理方面的基础研究。我的动机既有个人的好奇心，也有帮助该行业的真诚愿望。我认为这一领域是多学科的，利用物理、数学和工程。选择用于研究的项目来自与潜在研究生、行业和个人优先事项的接触。已完成的研究是：(A)研究高磁场强度(高Bl)对普通音盆扬声器功率效率的好处，特别是高Bl与开关或D类放大器相结合的好处，(B)研究正常密封箱单极扬声器的声学中心，特别是与了解扬声器在房间中的作用有关，以及(C)用一种新的、准确和快速的方法测量声学表面阻抗。新提出的扬声器研究将从以下几个方面进行选择：(I)进一步开展声学表面阻抗测量工作，(Ii)研究导致同心扬声器系统性能不佳的声学非线性，涉及移动边界的声学，和(Iii)研究粘弹性扬声器的衰减和锥体附近流动空气的惯性。我和一位同事研究抖动已有20多年，它是在量化器中加入噪声，将其失真和噪声调制转变为良性的低电平噪声。这些研究影响了数字音频蓬勃发展的方式。适当的抖动系统具有无限精细的信号分辨率，没有噪声调制，在它们的行为上变得真正模拟。我们将把这些相同的概念应用到图像处理中，将这些研究扩展到多位图像处理中的不同形式的抖动以及低位半色调中的部分抖动。目前正在进行的一个外围项目是研究声波在混凝土和其他土木工程固体中的传播，以检测缺陷和裂缝。

My aim is to support the audio engineering community with basic research in acoustics, electroacoustics, measurement tools, and signal processing.  It is motivated both by personal curiosity and a genuine desire to help the industry.  This area is multidisciplinary, drawing on physics, mathematics and engineering.  Projects chosen for study derive from contact with prospective graduate students, industry, and personal priorities.   Completed research is (a) a study of the benefits of a high magnetic field strength (high Bl) on the power efficiency of normal cone loudspeakers, especially the combined benefits of high Bl in combination with switching or class-D amplifiers, (b) a study of the acoustic centre of normal sealed-box monopolar loudspeakers, particularly relevant to understanding how loudspeakers act in rooms, and (c) measurement of acoustic surface impedance with a new, accurate and rapid method.  Newly-proposed loudspeaker research will be chosen from several areas: (i) further work on acoustic surface impedance measurements, (ii) a study of the acoustic nonlinearities that are responsible for the poor performance of concentric speaker systems, involving the acoustics of moving boundaries, and (iii) study of viscoeleastic loudspeaker damping and the inertia of the moving air near the cone.   For over 20 years a colleague and I have worked on dither, which is the addition of noise to a quantizer to turn its distortion and noise modulation into benign low-level noise.  These studies have influenced the way digital audio has flourished.  Properly dithered systems have infinitely fine signal resolution and no noise modulation, becoming truly analog in their behaviour.  We will apply these same concepts to image processing, extending these studies to different forms of dither in multi-bit image processing as well as partial dithering in low-bit half-toning.   An ongoing peripheral project is a study of the propagation of acoustic waves in concrete and other civil engineering solids, in order to detect flaws and cracks.