VoiceFixer: A Unified Framework for High-Fidelity Speech Restoration

Speech restoration aims to remove distortions in speech signals. Prior methods mainly focus on a single type of distortion, such as speech denoising or dereverberation. However, speech signals can be degraded by several different distortions simultaneously in the real world. It is thus important to extend speech restoration models to deal with multiple distortions. In this paper, we introduce VoiceFixer, a unified framework for high-fidelity speech restoration. VoiceFixer restores speech from multiple distortions (e.g., noise, reverberation, and clipping) and can expand degraded speech (e.g., noisy speech) with a low bandwidth to 44.1 kHz full-bandwidth high-fidelity speech. We design VoiceFixer based on (1) an analysis stage that predicts intermediate-level features from the degraded speech, and (2) a synthesis stage that generates waveform using a neural vocoder. Both objective and subjective evaluations show that VoiceFixer is effective on severely degraded speech, such as real-world historical speech recordings. Samples of VoiceFixer are available at https://haoheliu.github.io/voicefixer.Comment: Submitted to INTERSPEECH 202

Hybrid acoustic metamaterial as super absorber for broadband low-frequency sound

A hybrid acoustic metamaterial is proposed as a new class of sound absorber, which exhibits superior broadband low-frequency sound absorption as well as excellent mechanical stiffness/strength. Based on the honeycomb-corrugation hybrid core (H-C hybrid core), we introduce perforations on both top facesheet and corrugation, forming perforated honeycomb-corrugation hybrid (PHCH) to gain super broadband low-frequency sound absorption. Applying the theory of micro-perforated panel (MPP), we establish a theoretical method to calculate the sound absorption coefficient of this new kind of metamaterial. Perfect sound absorption is found at just a few hundreds hertz with two-octave 0.5 absorption bandwidth. To verify this model, a finite element model is developed to calculate the absorption coefficient and analyze the viscous-thermal energy dissipation. It is found that viscous energy dissipation at perforation regions dominates the total energy consumed. This new kind of acoustic metamaterials show promising engineering applications, which can serve as multiple functional materials with extraordinary low-frequency sound absorption, excellent stiffness/strength and impact energy absorption

3D In-situ XCT Image Based Meso-scale Fracture Modelling and Validation of Concrete Using Voxel Hexahedron Meshing and Damage Plasticity Model

Abstract Three-dimensional (3D) meso-scale finite element models of concrete in compression based on insitu X-ray Computed Tomography (XCT) images are developed and validated in this study. The micro-scale images from a Brazilian-like in-situ XCT test are first compressed and then transformed into manageable meso-scale 3D meshes using a voxel hexahedron meshing technique with a stacking algorithm. The concrete damaged plasticity model in ABAQUS is used to simulate complicated damage and fracture behaviour of concrete. Excellent qualitative agreement is found between the simulations and the XCT test in terms of damage evolution and fracture process on both the surface and interior of the specimen. The effects of internal heterogeneous meso-structures on the macro-scale loading-carrying capacities and failure patterns are quantitatively and qualitatively evaluated by modelling different uniaxial loading directions