Vehicle Cabin Audio Feedback Cancellation Using Shared Adaptive Filters

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Solution Overview

Problem

Existing communication support systems in vehicles face excessive system size and processing volume due to the need for additional adaptive filters to suppress audio feedback, alongside active noise control and echo cancellation.

Innovation Solution

A communication support system that uses a noise canceling adaptive filter and an audio feedback canceling section, with transfer function update processing, to suppress audio feedback without requiring a dedicated adaptive filter, employing the Filtered-X LMS algorithm for adaptive operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a dedicated adaptive filter is added to suppress audio feedback, then audio feedback suppression is improved, but device complexity and processing volume increase excessively

Engineering Contradiction:

Improveaudio feedback suppressionVSAvoidsystem size

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent makes the existing adaptive filter perform multiple functions: it simultaneously handles active noise control, echo cancellation, and audio feedback suppression. By configuring the adaptive filter to process multiple signal paths and apply different transfer functions for different purposes, the system eliminates the need for separate dedicated filters while maintaining all required functions.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the functions of multiple separate adaptive filters into a single unified adaptive filter. By combining audio feedback suppression with existing noise control and echo cancellation operations in one filter structure, the system reduces the total number of components and processing units required.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If a dedicated adaptive filter is added to suppress audio feedback, then audio feedback suppression is improved, but processing volume increases excessively

Engineering Contradiction:

Improveaudio feedback suppressionVSAvoidprocessing volume

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The single adaptive filter is configured to handle multiple signal processing tasks simultaneously, including noise control, echo cancellation, and audio feedback suppression. This multi-functional approach consolidates processing operations that would otherwise require separate computational resources.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines multiple processing functions into one adaptive filter structure, reducing the total computational load by eliminating redundant processing operations that would occur if separate filters were used for each function.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If multiple adaptive filters are used for active noise control and echo cancellation, then noise control and echo cancellation are improved, but device complexity increases

Engineering Contradiction:

Improvenoise control and echo cancellationVSAvoidsystem size

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The adaptive filter is configured to perform active noise control, echo cancellation, and audio feedback suppression using different transfer functions and signal paths. This multi-functional configuration allows one filter to replace what would traditionally require multiple separate filters.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges noise control and echo cancellation functions into a single adaptive filter structure, reducing system complexity while maintaining the effectiveness of both functions through proper configuration of transfer functions and signal routing.

Inventive Principle:

Principle #5Merging (Combining)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Effectively suppresses audio feedback in vehicle communication systems by diverting transfer functions of adaptive filters for noise and echo cancellation, reducing system complexity and processing volume.

Implementation Method 1

Methodology Applied

Scientific EffectFiltered-X LMS algorithm:

Implementation Method 2

an echo cancel technique is used. That is, in a system for supporting conversation between a user in a first area and a user in a second area by outputting a user's voice picked up by a microphone 41 in the first area from a speaker 43 in the second area

Methodology Applied

Scientific EffectEcho cancellation: Echo

Data Source

PatentEP4236284B1Communication support system

Publication Date: 2025.11.19 ALPS ALPINE CO LTD

Figure 1A~1B
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AI summary

A noise canceling adaptive filter outputs, from a front seat speaker, a noise canceling sound generated by applying a transfer function X(z) adapted by an adaptive operation using an output of a front seat microphone as an error to an output sound of a sound source apparatus. An output of the front seat microphone is added to an output of an audio feedback canceling filter by a second adder, added to an output sound of the sound source apparatus by a third adder, and output from a rear seat speaker. The audio feedback canceling filter applies a transfer function X'(z) and a transfer function C^(z) on an output of the second adder and outputs a resultant. The transfer function C^(z) corresponds to a transfer function C(z) from the front seat speaker to the front seat microphone. In synchronization control, the transfer function X(z) is set as the transfer function X'(z).