Traditionally, fixed bit-rate speech coding is used in VoIP system. This technology can not adaptively switch its bit-rate due to network condition. So we select AMR speech coder.The AMR speech coder consists of the multi-rate speech coder, a source controlled rate scheme including a voice activity detector and a comfort noise generation system, and an
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With the development of computer, network and communication technology, multimedia data, which include image, video and audio, becomes primary information media in the field of information processing. Audio data is an important part of multimedia applications.Raw audio data is non-semantic and non-structured binary data stream which lacks semantic content description and structured organization. These characteristics
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As computer science and information technology develop, speech recognition will become the main communication tool between human and machine. Through its development in about half a century, speech recognition technology has become more and more perfect and there are more and more products that are changing people’s life.Speech recognition system has been widely used in
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AMR(Adaptive Multi-Rate) is a codec recommended by 3GPP WCDMA. It is a typical ACELP codec with multimode. Its coding mode can be adjusted according to radio environment to enhance its ability to resist bit error and improve quality and capacity. As 3G gains more and more popularity, AMR will play a more important role in
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In speech signal processing, distinguished the speech and no-speech from speech signal defined as speech endpoint detection.Accurate endpoint detection will increase the channel utilization and reduce the amount of data with speech processing. Early endpoint detection algorithm based on short-term energy and zero crossing rate, cepstrum distance, spectral entropy. However, these methods are difficult to
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The purpose of voice activity detection (VAD) is detecting the beginning and ending points of speech from a signal which contains speech. As a pre-operation of speech signal processing, VAD is very important and has potential applications in the areas of speech enhancement, coding, identification and so on. VAD methods could be divided into two
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Speech communication plays an important role in modern communication.G.729 that was issued by ITU-T in 1996 is widely used owning to its high compression rate and excellent quality in synthetic speech. Several algorithms such as voice activation detection, are added in G.729B in order to decrease the code rate and improve the spectral efficiency. However,
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With the popularity of automobile, research on how to attenuate car interior noise becomes one of the focuses in the realm of signal processing. Active noise cancellation earphone is fit for this application. The prototype of this kind of earphone is Adaptive Active Noise Control (AANC) system, which bases on the theory of Adaptive Filtering.
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The object that speech recognition technology researches is speech signal processing. This technology can make the machine understand natural language of mankind and can be human-computer interaction interface.Now, in ideal environment, most speech recognition products can have a high recognition rate. But in noisy environment, the rate reduced rapidly. So how to improve the performance
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With the rapid development of science and technology, voice communications technology is becoming more and more mature. Voice is a very important way of communication between humans, and voice quality will affect the communication and exchange between people. In real life, when using mobile phone, microphone, telephone and other communications equipment in such as military
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