Mixed Near-Filed And Far-Filed Speech Source Localization Based On Microphone Arrays

The localization of sound source is the basis and prerequisite for realization of speech recognition and speech enhancement. It has broad application prospects. As the development of the technology of the digital and array signal’s processing, the microphone array has been widely used in the localization of sound source, but the most of sound source localization based on microphone array technology, either completely in near field source, or in the far field source. The most assuming source is narrow-band signal, but voice signal in real life is broadband signal.To solve these problems, this paper deeply studied in the case of mixed near field and far field of sound source localization based on microphone array technology. The main contents can be stated as follows:First, it analyses the characteristics of the speech signal, introduces the traditional narrow band signal processing model and broadband signal processing model, and studies the model of the uniform linear array microphone array in the far field and near field.Second, it is necessary to preprocess the data because the microphone array receives both the useful speech signal and all other kinds of noise. The preprocessing includes pre-filtering, pre-emphasis and normalization, and window frame, short-time energy detection, and voice noise reduction, etc. In this paper, the voice activity detection is studied. In order to take advantages of these two kinds of methods:logarithmic energy on the time domain and band-partitioning spectral entropy on the frequency domain, this paper gives a new logarithmic band-partitioning energy spectral entropy.Third, it studies the near-field MUSIC algorithm, and the signal model with the situation that the signal is in both the far field and the near field, and gives the algorithm of using MUSIC algorithm to locate the wideband speech signal in the hybrid field. The algorithm first separates the arrival direction and distance of the signal source, then gets a direction matrix which only contains the information of arrival direction. Then we can get the arrival angle of all sources with the apply of the MUSIC algorithm. At the end, we can obtain the far field and near field sound source localization through the MUSIC algorithm, based on the characteristics of the information of arrival direction and the far field.Last, it studies the sound source localization algorithm based on sparse decomposition in the near field and the mixed field. When the source is mixed in field, this paper, based on the signal model of hybrid field, puts forward the mixed structure suitable for microphone array field method of atomic library, and then succeeds in estimating the direction in mixed field of the sound, using the matching pursuit. Simulation shows that the algorithm has good robustness through the experiment under the condition of low signal-to-noise ratio.