Miipher-2: A Universal Speech Restoration Model for Million-Hour Scale Data Restoration

Fuente: arXiv
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Main Authors: Karita, Shigeki, Koizumi, Yuma, Zen, Heiga, Ishikawa, Haruko, Scheibler, Robin, Bacchiani, Michiel
Format: Preprint
Published: 2025
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author Karita, Shigeki
Koizumi, Yuma
Zen, Heiga
Ishikawa, Haruko
Scheibler, Robin
Bacchiani, Michiel
author_facet Karita, Shigeki
Koizumi, Yuma
Zen, Heiga
Ishikawa, Haruko
Scheibler, Robin
Bacchiani, Michiel
contents Training data cleaning is a new application for generative model-based speech restoration (SR). This paper introduces Miipher-2, an SR model designed for million-hour scale data, for training data cleaning for large-scale generative models like large language models. Key challenges addressed include generalization to unseen languages, operation without explicit conditioning (e.g., text, speaker ID), and computational efficiency. Miipher-2 utilizes a frozen, pre-trained Universal Speech Model (USM), supporting over 300 languages, as a robust, conditioning-free feature extractor. To optimize efficiency and minimize memory, Miipher-2 incorporates parallel adapters for predicting clean USM features from noisy inputs and employs the WaveFit neural vocoder for waveform synthesis. These components were trained on 3,000 hours of multi-lingual, studio-quality recordings with augmented degradations, while USM parameters remained fixed. Experimental results demonstrate Miipher-2's superior or comparable performance to conventional SR models in word-error-rate, speaker similarity, and both objective and subjective sound quality scores across all tested languages. Miipher-2 operates efficiently on consumer-grade accelerators, achieving a real-time factor of 0.0078, enabling the processing of a million-hour speech dataset in approximately three days using only 100 such accelerators.
format Preprint
id arxiv_https___arxiv_org_abs_2505_04457
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Miipher-2: A Universal Speech Restoration Model for Million-Hour Scale Data Restoration
Karita, Shigeki
Koizumi, Yuma
Zen, Heiga
Ishikawa, Haruko
Scheibler, Robin
Bacchiani, Michiel
Sound
Computation and Language
Audio and Speech Processing
Training data cleaning is a new application for generative model-based speech restoration (SR). This paper introduces Miipher-2, an SR model designed for million-hour scale data, for training data cleaning for large-scale generative models like large language models. Key challenges addressed include generalization to unseen languages, operation without explicit conditioning (e.g., text, speaker ID), and computational efficiency. Miipher-2 utilizes a frozen, pre-trained Universal Speech Model (USM), supporting over 300 languages, as a robust, conditioning-free feature extractor. To optimize efficiency and minimize memory, Miipher-2 incorporates parallel adapters for predicting clean USM features from noisy inputs and employs the WaveFit neural vocoder for waveform synthesis. These components were trained on 3,000 hours of multi-lingual, studio-quality recordings with augmented degradations, while USM parameters remained fixed. Experimental results demonstrate Miipher-2's superior or comparable performance to conventional SR models in word-error-rate, speaker similarity, and both objective and subjective sound quality scores across all tested languages. Miipher-2 operates efficiently on consumer-grade accelerators, achieving a real-time factor of 0.0078, enabling the processing of a million-hour speech dataset in approximately three days using only 100 such accelerators.
title Miipher-2: A Universal Speech Restoration Model for Million-Hour Scale Data Restoration
topic Sound
Computation and Language
Audio and Speech Processing
url https://arxiv.org/abs/2505.04457