Self-Attention Audio Denoising for Multi-Channel Spectrum

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Solution Overview

Problem

Existing methods for denoising multi-channel audio signals, such as those used in speech recognition, are limited in effectively representing the multi-channel spectrum and require recurrent neural networks to estimate mixing coefficients, which can be inefficient.

Innovation Solution

A novel self-attention mechanism is employed to compute channel mixing weights for each time-frequency component of a multi-channel audio signal, allowing each time-frequency bin to be aware of all other bins across channels, thereby enhancing the representation of the multi-channel spectrum and denoising the signal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a recurrent neural network is used to estimate mixing coefficients, then denoising can be performed, but the processing efficiency is reduced and the representation of multi-channel spectrum is limited

Engineering Contradiction:
Improvedenoising performanceVSAvoidprocessing efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent replaces the recurrent neural network (RNN) mechanism with a self-attention mechanism. The self-attention mechanism computes mixing coefficients through parallel attention computations across all time-frequency bins simultaneously, eliminating the sequential processing bottleneck of RNNs while maintaining or improving denoising performance through better spectral representation.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent transforms the processing approach by introducing a global attention dimension that considers all time-frequency bins across all channels simultaneously. The self-attention mechanism computes attention weights that capture long-range dependencies and global spectral patterns, adding a dimensional perspective that RNNs cannot achieve through their sequential nature.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Reliability

If conventional approaches are used, then mixing coefficients can be estimated, but the multi-channel spectrum representation is insufficient

Engineering Contradiction:
Improvemixing coefficient estimationVSAvoidmulti-channel spectrum information
Core Design Contradiction:
ReliabilityVSLoss of information

Solution Approach 1:

The self-attention mechanism implements a feedback loop where each time-frequency bin's representation is continuously refined by attending to all other bins. The attention weights are computed based on queries, keys, and values from all channels, and the resulting attended representations are fed back to update the mixing coefficients, creating an iterative refinement process that preserves spectral information.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The self-attention mechanism serves multiple functions simultaneously: it estimates mixing coefficients, represents multi-channel spectrum information, captures temporal and spectral dependencies, and performs denoising. This universal approach replaces the specialized RNN architecture with a single mechanism that handles all these tasks through its attention-based computation.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP3994690B1Audio processing apparatus and method for denoising a multi-channel audio signal
Publication Date: 2024.06.19 HUAWEI TECH CO LTD
  • EP3994690B1 patent drawingFigure 1
  • EP3994690B1 patent drawingFigure 2
  • EP3994690B1 patent drawingFigure 3

AI summary

The invention relates to an audio processing apparatus (100), comprising: a plurality of audio sensors (101), each audio sensor (101) configured to receive a respective plurality of audio frames of an audio signal from an audio source, wherein the respective plurality of audio frames defines an audio channel of the audio signal; and a processing circuitry (103) configured to: determine a respective feature set having at least one feature for each audio frame of each of the plurality of audio frames, wherein the plurality of features define a three-dimensional feature array; process the three-dimensional feature array using a neural network, wherein the neural network comprises a self-attention layer configured to process a plurality of two-dimensional sub-arrays of the three-dimensional feature array; and generate an output signal on the basis of the plurality of processed two- dimensional sub-arrays. Moreover, the invention relates to a corresponding audio processing method.