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Main Authors: Kondo, Yuto, Kameoka, Hirokazu, Tanaka, Kou, Kaneko, Takuhiro
Format: Preprint
Published: 2025
Subjects:
Online Access:https://arxiv.org/abs/2506.18326
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author Kondo, Yuto
Kameoka, Hirokazu
Tanaka, Kou
Kaneko, Takuhiro
author_facet Kondo, Yuto
Kameoka, Hirokazu
Tanaka, Kou
Kaneko, Takuhiro
contents The automatic speech quality assessment (SQA) has been extensively studied to predict the speech quality without time-consuming questionnaires. Recently, neural-based SQA models have been actively developed for speech samples produced by text-to-speech or voice conversion, with a primary focus on training mean opinion score (MOS) prediction models. The quality of each speech sample may not be consistent across the entire duration, and it remains unclear which segments of the speech receive the primary focus from humans when assigning subjective evaluation for MOS calculation. We hypothesize that when humans rate speech, they tend to assign more weight to low-quality speech segments, and the variance in ratings for each sample is mainly due to accidental assignment of higher scores when overlooking the poor quality speech segments. Motivated by the hypothesis, we analyze the VCC2018 and BVCC datasets. Based on the hypothesis, we propose the more reliable representative value N_low-MOS, the mean of the $N$-lowest opinion scores. Our experiments show that LCC and SRCC improve compared to regular MOS when employing N_low-MOS to MOSNet training. This result suggests that N_low-MOS is a more intrinsic representative value of subjective speech quality and makes MOSNet a better comparator of VC models.
format Preprint
id arxiv_https___arxiv_org_abs_2506_18326
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Selecting N-lowest scores for training MOS prediction models
Kondo, Yuto
Kameoka, Hirokazu
Tanaka, Kou
Kaneko, Takuhiro
Sound
Audio and Speech Processing
The automatic speech quality assessment (SQA) has been extensively studied to predict the speech quality without time-consuming questionnaires. Recently, neural-based SQA models have been actively developed for speech samples produced by text-to-speech or voice conversion, with a primary focus on training mean opinion score (MOS) prediction models. The quality of each speech sample may not be consistent across the entire duration, and it remains unclear which segments of the speech receive the primary focus from humans when assigning subjective evaluation for MOS calculation. We hypothesize that when humans rate speech, they tend to assign more weight to low-quality speech segments, and the variance in ratings for each sample is mainly due to accidental assignment of higher scores when overlooking the poor quality speech segments. Motivated by the hypothesis, we analyze the VCC2018 and BVCC datasets. Based on the hypothesis, we propose the more reliable representative value N_low-MOS, the mean of the $N$-lowest opinion scores. Our experiments show that LCC and SRCC improve compared to regular MOS when employing N_low-MOS to MOSNet training. This result suggests that N_low-MOS is a more intrinsic representative value of subjective speech quality and makes MOSNet a better comparator of VC models.
title Selecting N-lowest scores for training MOS prediction models
topic Sound
Audio and Speech Processing
url https://arxiv.org/abs/2506.18326