Multi-Metric Preference Alignment for Generative Speech Restoration

TL;DR

This paper introduces a multi-metric preference alignment approach for generative speech restoration, improving model quality by aligning with human perceptual preferences through a new dataset and multi-metric optimization.

Contribution

It proposes a novel multi-metric preference alignment strategy, including a new dataset and application of DPO, to enhance speech restoration models across various paradigms.

Findings

Significant performance improvements across multiple models and benchmarks.

Multi-metric approach reduces reward hacking compared to single-metric methods.

Aligned models effectively generate pseudo-labels for data-scarce tasks.

Abstract

Recent generative models have significantly advanced speech restoration tasks, yet their training objectives often misalign with human perceptual preferences, resulting in suboptimal quality. While post-training alignment has proven effective in other generative domains like text and image generation, its application to generative speech restoration remains largely under-explored. This work investigates the challenges of applying preference-based post-training to this task, focusing on how to define a robust preference signal and curate high-quality data to avoid reward hacking. To address these challenges, we propose a multi-metric preference alignment strategy. We construct a new dataset, GenSR-Pref, comprising 80K preference pairs, where each chosen sample is unanimously favored by a complementary suite of metrics covering perceptual quality, signal fidelity, content consistency, and timbre preservation. This principled approach ensures a holistic preference signal. Applying Direct Preference Optimization (DPO) with our dataset, we observe consistent and significant performance gains across three diverse generative paradigms: autoregressive models (AR), masked generative models (MGM), and flow-matching models (FM) on various restoration benchmarks, in both objective and subjective evaluations. Ablation studies confirm the superiority of our multi-metric strategy over single-metric approaches in mitigating reward hacking. Furthermore, we demonstrate that our aligned models can serve as powerful ''data annotators'', generating high-quality pseudo-labels to serve as a supervision signal for traditional discriminative models in data-scarce scenarios like singing voice restoration. Demo Page:https://gensr-pref.github.io