Sound Signal Processing Apparatus for Echo Distortion Suppression
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Solution Overview
Problem
Conventional echo cancellers fail to suppress distortion in sound signals output to loudspeakers, leading to poor sound quality in communication systems like handsfree devices, as they do not account for non-linear characteristics introduced by amplifiers.
Innovation Solution
A sound signal processing apparatus that includes a correlation value calculator, determiner, and suppressor to assess and suppress the level of sound signals based on their correlation with echo signals, preventing distortion and cracking sounds at the loudspeaker.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the sound signal level is increased to improve communication quality, then the sound quality improves, but distortion occurs due to amplifier saturation
Solution Approach 1:
The system performs preliminary detection of the correlation between the sound signal and echo signal before the amplifier reaches saturation. By calculating the correlation value in advance and determining whether suppression is needed, the system prevents distortion before it occurs, rather than attempting to correct it after amplifier saturation has happened.
Solution Approach 2:
The system establishes a feedback loop where the correlation value calculator continuously monitors the relationship between the sound signal and echo signal, the determiner decides whether suppression is necessary, and the suppressor adjusts the sound signal level accordingly. This closed-loop feedback mechanism dynamically maintains optimal signal levels to prevent distortion while preserving communication quality.
2Object-generated harmful factors
If conventional echo canceller is used to cancel echo, then echo cancellation is achieved, but distortion of the sound signal is not suppressed
Solution Approach 1:
The system merges the echo cancellation function with a new distortion suppression function. The correlation value calculator and determiner work together with the existing echo cancellation mechanism, combining both functions into a unified system that simultaneously achieves echo cancellation and distortion suppression through integrated signal processing.
Solution Approach 2:
The correlation value calculator acts as an intermediary between the sound signal and the echo cancellation process. By introducing this intermediate detection step, the system can assess the relationship between signals and make informed decisions about suppression, bridging the gap between simple echo cancellation and sophisticated distortion prevention.
3Object-affected harmful factors
If the sound signal level is suppressed to prevent distortion, then distortion is reduced, but the communication quality may deteriorate
Solution Approach 1:
The system applies suppression selectively rather than uniformly. By calculating the correlation value and determining suppression needs on a case-by-case basis, the system applies distortion suppression only when and where it is necessary, preserving communication quality in situations where suppression is not needed while preventing distortion when correlation indicates risk.
Data Source
AI summary
In a sound signal processing apparatus, a communication part receives a far-end sound signal from a smartphone serving as a sound source. A correlation value calculator calculates a correlation value indicative of a correlation between the far-end sound signal and a sending sound signal that includes an echo signal deriving from the far-end sound signal. When the correlation value is equal to or smaller than a predetermined suppression threshold, a determiner determines to suppress the far-end sound signal. When the determiner has determined to suppress the far-end sound signal, a suppressor suppresses the far-end sound signal, and outputs the suppressed far-end sound signal to a sound volume adjuster.