Controllable Waveform Pulse Sound Generation Technology

In applied acoustics field, the sound absorption measurement of an acoustic material and structure is always an important and basic task. At present, some traditional lab methods, including the standing wave tube method and the reverberation room method, are commonly used. The result of these measurements gives the acoustic absorption performance of the specimen in standard acoustic conditions and provides an important reference for its application. However, this performance is usually different from that measured in an actual environment. As a result, some modern techniques which are applicable for in—suit measurement have been developed. Most of these techniques use the Echo-impulse method. Therefore, an impulsive sound source with excellent performance is a key problem because it is an indispensable tool for the sound absorption measurement in the Echo-impulse method.According to the requirement of the time-domain parameter inversion method, a digitally-controlled impulsive sound source has been successful developed. The principle, design and experiment are introduced in this paper.The main achievements of this paper are as follows.The frequency response function (FRF) of an electric-acoustic system is analyzed, and the pulse FFT method is selected for the measurement and solution of the impulsive source' FRF. Several excitation signals, including the function of butterworth filter, chebyshev filter and white noise signal are discussed when they are used for FRF measurement. Some sound pulses, such as single cycle sinusoidal signal, damped single cycle sinusoidal signal and differential guassian signal, are designed and simulated. The pulse lengths are 1ms and 0.5ms. The driven signal of the impulsive source is finally calculated. Experiment result show that the developed impulsive source can radiate the desired sound pulses successfully.The impulsive source is designed and produced. Digital control is implemented by data acquisition card of Nl DAQCard—PXI4A72 or Nl DAQCard-PCMClA6062E. Good quality sound pulses are generated by this source in a semi-anechoic chamber. Propagation experiment validates it a...