Speaking in Wavelet Domain: A Simple and Efficient Approach to Speed up Speech Diffusion Model
Xiangyu Zhang, Daijiao Liu, Hexin Liu, Qiquan Zhang, Hanyu Meng, Leibny Paola Garcia, Eng Siong Chng, Lina Yao
TL;DR
The paper tackles the slow training and inference costs of speech diffusion models by shifting the generative target to the wavelet domain. By applying a Discrete Wavelet Transform (CDF 5/3) to obtain $c_A$ and $c_D$ and training on the concatenated $y=[c_A;c_D]$, the approach halves data length and memory while maintaining or improving speech quality. It demonstrates effectiveness on both synthesis and enhancement tasks (DiffWave and CDiffuSE) and introduces a Low-frequency Enhancer and a Multi-Level Wavelet Accelerator to push speedups beyond 5× with modest quality changes. This wavelet-centric, front-end strategy offers a practical, model-agnostic path to faster, scalable diffusion-based speech systems and highlights task-dependent wavelet choices for optimal results.
Abstract
Recently, Denoising Diffusion Probabilistic Models (DDPMs) have attained leading performances across a diverse range of generative tasks. However, in the field of speech synthesis, although DDPMs exhibit impressive performance, their long training duration and substantial inference costs hinder practical deployment. Existing approaches primarily focus on enhancing inference speed, while approaches to accelerate training a key factor in the costs associated with adding or customizing voices often necessitate complex modifications to the model, compromising their universal applicability. To address the aforementioned challenges, we propose an inquiry: is it possible to enhance the training/inference speed and performance of DDPMs by modifying the speech signal itself? In this paper, we double the training and inference speed of Speech DDPMs by simply redirecting the generative target to the wavelet domain. This method not only achieves comparable or superior performance to the original model in speech synthesis tasks but also demonstrates its versatility. By investigating and utilizing different wavelet bases, our approach proves effective not just in speech synthesis, but also in speech enhancement.
