scholarly journals System for receiving and processing diversity acoustic noise control data

2019 ◽  
Vol 30 ◽  
pp. 04005
Author(s):  
V. V. Tersin ◽  
V. V. Bulkin ◽  
T. D. Khromulina
Keyword(s):  
Fourier Transform ◽  
Noise Control ◽  
Acoustic Noise ◽  
Audio Signal ◽  
Sampling Frequency ◽  
Control Data ◽  
Graphical Programming ◽  
Advantages And Disadvantages ◽  
System Check ◽  
Acoustic Chamber

The results of the development and experimental verification of a system for obtaining and processing diversity acoustic noise control data are presented. The system is implemented using the LabView G graphical programming language. The length of the measured realization is determined by the ratio of the sample size to the sampling frequency. The number of measurements of each sound signal is determined by the ratio of the analysis time to the length of the measured realization. The measured audio signal implementation in the form of 40,000 16-bit binary numbers is processed using the fast Fourier transform. The result is a discrete spectrum of the audio signal in the range from 0 to 20 KHz with a step of 1 Hz. The results of the system check using a laboratory acoustic chamber and a noise shield are presented. The advantages and disadvantages of the system are formulated.

scholarly journals Modified GSC Method to Reduce the Distortion of the Enhanced Speech Signal Using Cross-Correlation and Sidelobe Neutralization

2021 ◽  
Vol 11 (14) ◽  
pp. 6288
Author(s):  
Hang Su ◽  
Chang-Myung Lee
Keyword(s):  
Speech Signal ◽  
Output Signal ◽  
Cross Correlation ◽  
Acoustic Noise ◽  
Audio Signal ◽  
Noise Signal ◽  
Lms Algorithm ◽  
Least Mean Square ◽  
Experiment Data ◽  
Noise Component

The generalized sidelobe canceller (GSC) method is a common algorithm to enhance audio signals using a microphone array. Distortion of the enhanced audio signal consists of two parts: the residual acoustic noise and the distortion of the desired audio signal, which means that the desired audio signal is damaged. This paper proposes a modified GSC method to reduce both kinds of distortion when the desired audio signal is a non-stationary speech signal. First, the cross-correlation coefficient between the canceling signal and the error signal of the least mean square (LMS) algorithm was added to the adaptive process of the GSC method to reduce the distortion of the enhanced signal while the energy of the desired signal frame was increased suddenly. The sidelobe pattern of beamforming was then presented to estimate the noise signal in the beamforming output signal of the GSC method. The noise component of the beamforming output signal was decreased by subtracting the estimated noise signal to improve the denoising performance of the GSC method. Finally, the GSC-SN-MCC method was proposed by merging the above two methods. The experiment was performed in an anechoic chamber to validate the proposed method in various SNR conditions. Furthermore, the simulated calculation with inaccurate noise directions was conducted based on the experiment data to inspect the robustness of the proposed method to the error of the estimated noise direction. The experiment data and calculation results indicated that the proposed method could reduce the distortion effectively under various SNR conditions and would not cause more distortion if the estimated noise direction is far from the actual noise direction.

scholarly journals Multichannel Feedforward Active Noise Control System with Optimal Reference Microphone SelectorBased on Time Difference of Arrival

2018 ◽  
Vol 8 (11) ◽  
pp. 2291 ◽  
Author(s):  
Kenta Iwai ◽  
Satoru Hase ◽  
Yoshinobu Kajikawa
Keyword(s):  
Noise Control ◽  
Acoustic Noise ◽  
Control Point ◽  
Active Noise Control ◽  
Broadband Noise ◽  
Time Difference ◽  
Arrival Direction ◽  
Noise Sources ◽  
Time Difference Of Arrival ◽  
Active Noise

In this paper, we propose a multichannel active noise control (ANC) system with an optimal reference microphone selector based on the time difference of arrival (TDOA). A multichannel feedforward ANC system using upstream reference signals can reduce various noises such as broadband noise by arranging reference microphones close to noise sources. However, the noise reduction performance of an ANC system degrades when the noise environment changes, such as the arrival direction. This is because some reference microphones do not satisfy the causality constraint that the unwanted noise propagates to the control point faster than the anti-noise used to cancel the unwanted noise. To solve this problem, we propose a multichannel ANC system with an optimal reference microphone selector. This selector chooses the reference microphones that satisfy the causality constraint based on the TDOA. Some experimental results demonstrate that the proposed system can choose the optimal reference microphones and effectively reduce unwanted acoustic noise.

Defect Detection Using Pulse Phase Thermography - Repeatability and Reliability of Data

2013 ◽  
Vol 569-570 ◽  
pp. 1164-1169
Author(s):  
Rachael C. Waugh ◽  
Janice M. Dulieu-Barton ◽  
Simon Quinn
Keyword(s):  
Fourier Transform ◽  
Standard Deviation ◽  
Defect Detection ◽  
Phase Contrast ◽  
Initial Temperature ◽  
Processing Parameters ◽  
Sampling Interval ◽  
Sampling Frequency ◽  
Pulse Phase ◽  
Peak Phase

A study has been carried out to characterize the effect of variation of processing parameters on the phase contrast data between defective and defect-free areas obtained through the use of pulse phase thermography (PPT). Processing parameters used to implement the fast Fourier transform (FFT) have been varied. Phase contrast was maximized when the datum used as the start point for the FFT was taken as the frame just after the pulse. Optimum recording duration was found when the surface temperature had returned to its initial temperature. A truncation shorter than this resulted in a reduced phase contrast. Sampling interval and range is required to be balanced against the quantity of data produced and the computational expense. A sampling frequency of 0.06 Hz was suggested for the sample studied as this allowed peak phase contrast to be captured without unnecessarily increasing data size. Repeatability of tests was also investigated. It was found that PPT phase contrast results have been found to be repeatable with a maximum standard deviation of 6°.

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