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Structured Sparse Spectral Transforms and Structural Measures for Voice Conversion
Journal article   Peer reviewed

Structured Sparse Spectral Transforms and Structural Measures for Voice Conversion

Yunxin Zhao, Mili Kuruvilla-Dugdale and Minguang Song
IEEE/ACM transactions on audio, speech, and language processing, Vol.26(12), pp.2267-2276
12/01/2018
DOI: 10.1109/TASLP.2018.2860682
PMCID: PMC6980218
PMID: 31984214
url
https://www.ncbi.nlm.nih.gov/pmc/articles/6980218View
Open Access

Abstract

We investigate a structured sparse spectral transform method for voice conversion (VC) to perform frequency warping and spectral shaping simultaneously on high-dimensional (D) STRAIGHT spectra. Learning a large transform matrix for high-D data often results in an overfit matrix with low sparsity, which leads to muffled speech in VC. We address this problem by using the frequency-warping characteristic of a source-target speaker pair to define a region of support (ROS) in a transform matrix, and further optimize it by nonnegative matrix factorization (NMF) to obtain structured sparse transform. We also investigate structural measures of spectral and temporal covariance and variance at different scales for assessing VC speech quality. Our experiments on ARCTIC dataset of 12 speaker pairs show that embedding the ROS in spectral transforms offers flexibility in tradeoffs between spectral distortion and structure preservation, and the structural measures provide quantitatively reasonable results on converted speech. Our subjective listening tests show that the proposed VC method achieves a mean opinion score of "very good" relative to natural speech, and in comparison with three other VC methods, it is the most preferred one in naturalness and in voice similarity to target speakers.
Acoustics Engineering Engineering, Electrical & Electronic Science & Technology Technology

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