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    Please use this identifier to cite or link to this item: http://asiair.asia.edu.tw/ir/handle/310904400/26293

    Title: 在二維聲譜濾波法中使用諧波調適提升語音增強系統效能之研究
    Authors: 陸清達
    Contributors: 資訊學院;資訊傳播學系
    Keywords: 語音增強;聽覺遮蔽閾值;後處理;二維聲譜濾波;音樂型殘留雜訊;母音諧 波頻譜調適;speech enhancement;auditory masking threshold;post processing;two-dimension spectrogram filtering;musical residual noise;harmonic spectrum adaptation
    Date: 2012
    Issue Date: 2013-07-18 15:57:01 (UTC+8)
    Abstract: 有許多的語音增強處理系統已經成功地用來從事改善受到各種雜訊干擾的語音信 號,但是大部分的方法,都面臨殘留雜訊過多與語音失真太嚴重的問題。我們經過仔細 的研究發現:使用聽覺遮蔽閾值調適的方法處理受干擾語音信號,可以藉由保留人耳聽 不見的殘留雜訊,維持較多的受干擾語音信號,達到降低語音失真的目的;可是受到背 景雜訊估計誤差的影響,造成增強後的語音信號中的音樂型殘留雜訊效應依然很明顯, 聽起也非常吵雜,其主因就是具有較大音強的殘留雜訊頻譜,隨機地分佈在相鄰次頻帶 與相鄰音框中所致;要如何降低音樂型殘留雜訊的效應,是一項迫切需要解決的問題。 有許多殘留雜訊抑制的後處理演算法,在抑制殘留雜訊頻譜的過程中,會造成嚴重的語 音失真,以及產生回音現象,使得後處理的效果不盡理想。本研究計畫嘗試透過語音增 強及後處理方式,大幅抑制殘留雜訊與提升語音品質;首先,使用聽覺遮蔽閾值調適的 語音增強演算法來抑制受干擾的語音信號,期使能效抑制背景雜訊,並且能維持高品質 的預處理語音信號;接著施以疊帶式諧波頻譜調適之二維聲譜濾波的後處理演算,大幅 的抑制音樂型殘留雜訊頻譜;並且融合重建母音諧波頻譜與合成子音信號,提升後處理 的語音信號品質。

    Many speech enhancement systems have been employed to enhance a speech signal which is corrupted by various kinds of noise. Most of them suffer from a quantity of residual noise containment and serious speech distortion. After careful study on the research topics of speech enhancement, we find that the speech enhancement algorithm adapted by the auditory masking properties of the human ear performs better than the other state-of-the-art methods. It is attributed to the preservation of residual noise which is inaudible by the human ear. Due to the reservation of noisy speech, the speech distortion is reduced in the enhanced speech. However, the annoying musical residual noise still exists and is apparent. It is caused by incorrect estimation on the noise level, yielding musical residual tones with strong energy to randomly appear over the neighbor subbands and in successive frames. Thus, how to reduce the effect of musical residual noise is an import task for speech enhancement. Many residual noise reduction algorithms suffer from serious speech distortion and echo effect, resulting in the quality of enhanced speech to be deteriorated. In this project, we aim to improve the performances of the reduction of residual noise and of the improvement of speech quality by a post-processing system. Firstly, we will employ a speech enhancement system adapted by the human auditory masking properties to suppress background noise, while the speech quality should be maintained at a high level. The enhanced signal is called as pre-processed speech. Hence, an iterative-two-dimensional spectrogram filtering technique adapted by vowel harmonicity will be developed to significantly reduce the spectra of musical residual noise. Furthermore, we will also try to reconstruct harmonic spectra and synthesize consonants. They will be adequately synthesized with the filtered speech to produce the post-processed speech. Accordingly, the quality of the posed-processed speech can be significantly improved.
    Appears in Collections:[資訊傳播學系] 科技部研究計畫

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