Echo Suppression Device Adaptive Comfort Noise Generation
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Solution Overview
Problem
Existing echo suppression devices generate comfort noise based on white noise, which does not match ambient noise changes in environments like on-board communication devices, leading to unnatural sound experiences.
Innovation Solution
An echo suppression device that estimates ambient noise from the microphone signal to generate comfort noise, using a noise estimation unit, suppression unit, and superimposition unit to create a natural sound experience by adjusting noise levels in each frequency band and only adding noise where necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If comfort noise is generated based on white noise signal, then the echo suppression device can reduce acoustic echo, but the comfort noise has magnitude and timbre different from actual ambient noise causing unnatural sound
Solution Approach 1:
The patent changes the parameters of comfort noise generation from fixed white noise to adaptive noise based on estimated ambient noise characteristics. The noise estimation unit analyzes the input signal to determine actual ambient noise parameters (magnitude, timbre, frequency distribution), and the comfort noise generation unit adjusts these parameters dynamically to match the estimated ambient noise, resolving the contradiction between echo suppression effectiveness and naturalness.
2Reliability
If comfort noise is added to maintain background sound, then overlapping parts between transmitting and receiving voices are reduced, but the voice from transmitting side becomes soundless and uncomfortable
Solution Approach 1:
The patent applies partial action by selectively adding comfort noise only in frequency bands and time periods where it is actually needed. The noise estimation unit identifies regions with excessive echo suppression (where voice becomes soundless), and the comfort noise generation unit adds noise only to those specific regions rather than uniformly across all frequencies and time, thus maintaining background sound while preserving voice clarity.
3Reliability
If echo removal is performed to reduce acoustic echo, then the acoustic echo is reduced, but the noise signal is also suppressed making the sound unnatural
Solution Approach 1:
The patent introduces an intermediary comfort noise signal that mediates between the echo-removed signal and the final output. The comfort noise generation unit generates this intermediary noise based on estimated ambient noise characteristics, and the superimposition unit adds it to the echo-removed signal. This intermediary noise compensates for the unnaturalness caused by excessive echo removal while not interfering with the echo suppression effectiveness.
Data Source
AI summary
There is provided an echo suppression device that allows adding a natural comfort noise even in an environment in which a change in ambient noise is large. An echo is removed from an input signal to generate an echo-removed signal, a noise signal included in the echo-removed signal is estimated to generate an estimated noise signal, and a noise signal included in the echo-removed signal is suppressed based on the estimated noise signal to generate a suppressed signal. A comfort noise is generated based on the estimated noise signal, and the comfort noise is superimposed on the suppressed signal.