Abstract
Public telephone systems transmit speech across a limited frequency range, about 300–3400 Hz, called narrowband (NB) which results in a significant reduction of quality and intelligibility of speech. This paper proposes a fully backward compatible novel method for bandwidth extension of NB speech. The method uses adaptive data hiding technique to provide a perceptually better wideband speech signal. The spectral envelope parameters are extracted from the high frequency components of speech signal existing above NB, which are then spread by using spreading sequences, and are embedded in the NB speech signal using adaptive data hiding technique. The embedded information is extracted at the receiving end to reconstruct the wideband speech signal. Theoretical and simulation analyses show that the proposed method is robust to quantization and channel noises. The log spectral distortion test clearly show that the reconstructed wideband signal gives a much better performance in terms of speech quality when compared to the conventional speech bandwidth extension methods employing data hiding.
Highlights
Speech transmission through existing telephone networks face difficulties in respect of losing a portion of speeches as frequency of human speeches lies beyond its bandwidth ranging between 300 and 40000 Hz
Artificial bandwidth extension (ABE) is considered as an effective BWE technique that works on the principle of mutual dependency of NB signal with out-of-band
Two channel models are used by the experiments which are regulated in this study provided below: (i) -law channel model. (ii) AWGN channel model with a signal to noise ratio (SNR) of 35 dB
Summary
Speech transmission through existing telephone networks face difficulties in respect of losing a portion of speeches as frequency of human speeches lies beyond its bandwidth ranging between 300 and 40000 Hz. Artificial bandwidth extension (ABE) is considered as an effective BWE technique that works on the principle of mutual dependency of NB signal with out-of-band It helps in estimating the information regarding out-of-band from NB signal and utilise those information to reconfigure the WB for enhancing the quality of speech. A suitable set of existing literature is present to suggest an alternative solution for improving the quality of telephonic speech in comparison to ABE techniques It includes transmission of additional information regarding out-of-band that results in improving the quality effectively [1]. As proposed by Zhe Chen et al [15] there is another technique of perception based least significant bit watermark method used for reconfiguring a high quality WB signal by embedding UB elements in the NB speech framework These components are extracted at the receiver’s end for reconstructing the WB signal.
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