Zhong Yan Jiong
Zhang Zhen Shan
Dept. of Automatic Control, Univ. of Sci. and Technol., Beijing 100083, People's Republic of China
In order to get the mathematic model of a noise control system in space, which is the impulse response of a speaker--microphone system, a square impulse modulated by a single frequency signal has been used. In the paper, a pseudorandom correlation identification method is used to get the impulse response of a MIMO speaker microphone system in the spatial field. The dynamic process and the time delay of sound waves in the spatial field and speaker coils are presented exactly. The model is used for digital simulation and a space sound experiment using a developed adaptive filter algorithm presented by the authors which is the recursive algorithm with interlacing cycle and increasing phase. The sampled noise signal from the motor driver cabin is used as the input of the system. The simulaiton and the experiment have proved the correctness of the model and the effectiveness of the developed adaptive fillter algorithm.
It is a well-known axiom that it is necessary for accurate calibrated acoustical instrumentation to be used in order to achieve accurate and repeatable measurements. The term ``calibration'' has different meanings to different people. The purpose of this session is to examine the topic of acoustical instrument calibration from a number of viewpoints. These viewpoints come from scientists, engineers, lawyers, and industrial hygienists who are acoustical instrument evaluators, manufacturers, and users. Perhaps attendees will come away from the session with a better understanding of the term ``calibration,'' or at least will give it some thought the next time they have an instrument calibrated.