Noise reduction combining time-frequency ε-filter and M-transform

Tomomi Abe*, Mitsuharu Matsumoto, Shuji Hashimoto

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review


    This paper introduces noise reduction combining time-frequency ε-filter (TF ε-filter) and time-frequency M-transform (TF M-transform). Musical noise is an offensive noise generated due to noise reduction in the time-frequency domain such as spectral subtraction and TF ε-filter. It has a deleterious effect on speech recognition. To solve the problem, M-transform is introduced. M-transform is a linear transform based on M-sequence. The method combining the time-domain ε-filter (TD ε-filter) and time-domain M-transform (TD M-transform) can reduce not only white noise but also impulse noise. Musical noise is isolated in the time-frequency domain, which is similar to impulse noise in the time domain. On these prospects, this paper aims to reduce musical noise by improving M-transform for the time-frequency domain. Noise reduction by using TD M-transform and the TD ε-filter is first explained to clarify its features. Then, an improved method applying M-transform to the time-frequency domain, namely TF M-transform, is described. Noise reduction combining the TF ε-filter and TF M-transform is also proposed. The proposed method can reduce not only high-level nonstationary noise but also musical noise. Experimental results are also given to demonstrate the performance of the proposed method.

    Original languageEnglish
    Pages (from-to)994-1005
    Number of pages12
    JournalJournal of the Acoustical Society of America
    Issue number2
    Publication statusPublished - 2008

    ASJC Scopus subject areas

    • Acoustics and Ultrasonics


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