Speech Enhancement Using Harmonic Regeneration

Abstract

This paper addresses the problem of single microphone speech enhancement in noisy environments. Common short-time noise reduction techniques introduce harmonic distortion in enhanced speech because of the non reliability of estimators for small signalto-noise ratios. We propose a new method called Harmonic Regeneration Noise Reduction technique which solves this problem. A fully harmonic signal is calculated based on the distorted signal using a non-linearity to regenerate harmonics in an efficient way. This artificial signal is then used to compute a suppression gain able to preserve the speech harmonics. This method is theoretically analyzed, then objective and formal subjective results are given and show a significant improvement compared to classical noise reduction techniques.

A new efficient two-channel backward algorithm for speech intelligibility enhancement: A subband approach

“…A several one-, two-and multichannel sensors techniques are proposed to deal with this problem. For example in [14][15][16][17], several single and two-sensor techniques are proposed to correct these distortions [18][19][20]. More advanced techniques are then proposed recently in [21,22].…”

Voice activity detection using harmonic frequency components in likelihood ratio test

“…To improve the noise-robustness of an ASR system trained using clean data, techniques such as speech enhancement [1][2][3][4], noise-robust feature extraction feature enhancement [5] [6], and model-based noise adaptation [7] can be applied. Most of these techniques require a reliable voice activity detector (VAD) to identify non-speech segments for noise estimation.…”

“…Nonlinear spectral subtraction (NSS) in [3] defined a smaller subtraction factor at harmonic peaks which resulted in higher ASR accuracy at low SNRs. In [4], regeneration of harmonic structures improved the quality of denoised speech. A harmonic model is used in a generalized LRT for robust voiced/unvoiced detection in [8], and a periodic-toaperiodic component ratio used for speech/non-speech detection in [9] showed promising results with aperiodic noise interferences.…”

Adaptive Weiner Filter for Speech Enhancement under Various Noisy Conditions

“…The distorted signal is processed to create a fully harmonic signal where all the missing harmonics are regenerated. Hence, this method is called as Harmonic Regeneration Noise Reduction (HRNR) method and it was presented in [3], [5], [8], [9]. Two-step noise reduction (TSNR), to refine the estimation of the a priori SNR which get rid of the drawbacks of the DD approach while maintaining its advantage, i.e.…”