Calibration Method Of Microphone Amplitude And Phase Mismatch Errors In 3D Sound Intensity Measurement

Microphone array is different from traditional single microphone systems.It can obtain the spatial information of the sound source,which makes it widely applicated in all kinds of speech processing system.By processed,they can realize sound source localization,speech enhancement,and speech separation.At present,signal processing algorithms based on microphone arrays are emerging one after another.Simulation has confirmed the effectiveness of these algorithms,but the actual test results are not ideal.One of the important reasons is that the array microphones have amplitude and phase mismatch errors.Therefore,it is of great significance to study microphone calibration methods.This paper takes the calibration of three-dimensional sound intensity probe array as the research goal,and studies two calibration methods: the exchange microphone method is studied,with a microphone as a reference to calibrate the microphone individually;an array active calibration method is studied,which directly calibrates the microphone array.The main research contents are:1)Combined with the theoretical knowledge of traditional array model,near-field far-field model and pulsating spherical source characteristics,and according to the specific conditions of the test,the near-field broadband microphone array signal model and error model were constructed.The effects of array amplitude and phase mismatch error on 3D sound intensity measurement and sound source localization algorithm are analyzed by simulation.2)The frequency response function method is difficult to ensure that the measurement points of the dual microphones are in the same sound field in the actual implementation.For this,the exchange microphone method is studied.Taking a microphone as a reference,the calibration function is obtained by performing two tests by swapping the position of the dual microphones.In order to ensure that the measurement points after the microphone exchange can coincide,a fixture for microphone calibration was designed.The fixture achieved the measurement point position of the exchange microphone by rotating the core member of the microphone installation by 180o.The feasibility of the exchange microphone method was verified by a single sound source localization experiment,and its performance was better than the frequency response function method.3)An active broadband near-field calibration method is studied for microphone array gain-phase mismatch errors.This method uses only one calibration source,and uses a linear sinusoidal sweep signal as the excitation signal.Firstly,it performs amplitude and phase compensation on the signals received by the array.One element in the array is used as the reference element,and the reference element and the element to be calibrated are regarded as a single-input-single-output linear system.Then,several FIR filters for channel calibration are obtained by the recursive least squares(RLS)system identification algorithm.The calibration and sound source localization experiments were carried out with a three-dimensional sound intensity probe array,and the proposed calibration method was verified to be practical and effective.