Voice Signal Noise Suppression with Timed Post-Detection Muting

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Solution Overview

Problem

Existing noise suppression techniques using adaptive filters are insufficient until they are optimized, and residual echo suppression units can inadvertently suppress signal components with small amplitudes along with residual echoes.

Innovation Solution

A noise suppression device that detects noise generation timing and separately suppresses the noise component in a voice signal for a predetermined period using a period suppression unit, preventing excessive suppression after adaptive filter optimization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an adaptive filter is used to suppress noise components, then noise suppression capability is improved, but suppression performance is insufficient until the adaptive filter is optimized

Engineering Contradiction:

Improvenoise suppression capabilityVSAvoidoptimization time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system performs preliminary noise suppression using a fixed filter before the adaptive filter optimization is complete. This preliminary action ensures acceptable noise suppression performance during the transient period when the adaptive filter is still learning, without waiting for full optimization to occur.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system alternates between fixed filter suppression and adaptive filter suppression based on the optimization state. During early stages, fixed filter provides periodic suppression; as optimization progresses, the system transitions to adaptive filter suppression, creating a periodic switching pattern that maintains performance throughout the optimization process.

Inventive Principle:

Principle #19Periodic action

2Reliability

If a residual echo suppression unit is used to suppress noise, then noise suppression is improved, but signal components with small amplitude are suppressed together with residual echoes

Engineering Contradiction:

Improvenoise suppression effectivenessVSAvoidvoice signal integrity

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The system applies different suppression characteristics to different parts of the signal processing chain. The fixed filter applies gentle suppression that preserves small amplitude components, while the adaptive filter applies stronger suppression only to identified noise components, creating local quality differences in the suppression approach.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The system dynamically adjusts the suppression strategy based on signal conditions. When voice signals with small amplitudes are detected, the system reduces suppression intensity to preserve these components. When only noise is present, full suppression is applied, making the suppression characteristic dynamic rather than static.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentEP3438977B1Noise suppression in a voice signal

Publication Date: 2020.01.29 FUJITSU LTD

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AI summary

A noise suppression device includes: an adaptive filter unit that suppresses, using an adaptive filter, a noise component contained in a voice signal generated from a voice captured by a voice input unit to generate a corrected voice signal; a noise generation detection unit that detects timing of generation of the noise component in the voice signal; and a period suppression unit that suppresses the corrected voice signal during a predetermined period of time after the timing of the generation of the noise component.