Research On Speech Enhance Method Of Microphone Array Of Mobile Phone

The noise and reverberation can affect the communication quality when we use mobile phone in daily life. The signal collected by microphone is not pure speech signal. In order to enhance the speech signal to improve the quality of the communication, microphone array use on mobile phone has become a hot research topic. Mutiple microphones are composed in an array according to certain rules, when the voice and environmental information is collected by multiple microphones, the microphone array can be adjusted to the filter coefficients for each channel, forming a beam to the target sound source in the desired direction effectively, enhancing signal within the beam, suppressing signals outside the beam, so as to achieve the purpose of extracting the sound source and suppressing noise simultaneously, which is the speech enhancement method based microphone array. Using a microphone array in the mobile terminal that have many problems, which is an emerging research topic. This paper mainly studies how to use the microphone array technology in mobile phone, in the condition of mobile phone hands-free and handheld mode, which technology can be used to enhance the speech quality.1. Summarized the existing time delay estimation techniques and microphone beamforming method, get their advantages and disadvantages and applicable environment. Find out an effective method can use on microphone array of mobile phone.2. To analysis the environment when we use mobile phone in hands-free mode, can get that room reverberation and far-field noise are two key elements of interference quality of call. Propose a scheme which filtering the signal before beam forming. According to the attenuation coefficient of indoor reverberation, proposed an improvement method to reduce the reverberation. The signal collected by microphone through dereverberation and denoising, then wight-sum to get the output signal. The result of the scheme is good through the test, but the effect of speech enhancement has declined when the noise increases.3. To analysis the environment when we use mobile phone in handheld mode and obtain the main elements which affect the quality of call is noise signal. GSC beamforming method can eliminate the relevant noise signal and Zelinski filtering method can eliminate the irrelevant noise effectively. We combine the two method to form a speech enhancement scheme. The experimental result is good. With the signal-to-noise ratio decreases, the speech enhancement effect decreased slowly.4. According to the diversity of mobile phone models, analysis the position of the sound source relative to the microphone and make the microphone array’s beam point to this direction. In this process, we need to take attention in people’s behavior. Some people used to take the mobile phone with the left hand, others used to take the mobile phone with the right hand.