Triangular Microphone Array for Vehicle Noise Reduction

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional microphones in vehicles face challenges in maintaining high signal-to-noise ratios due to ambient noise, particularly in vehicles, where noise levels fluctuate dynamically, affecting hands-free communication and voice recognition systems.

Innovation Solution

A microphone assembly with a triangular configuration of digital microphones and a digital signal processor (DSP) is integrated into a rearview mirror housing, utilizing sigma delta modulation and directional processing to reduce noise and enhance speech clarity by creating null regions and applying non-linear algorithms for noise suppression.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a single microphone is mounted in the mirror support, then the microphone location is known in advance and mounting is simplified, but the mirror blocks the direct path from the user to the microphone reducing speech signal quality

Engineering Contradiction:

Improvemicrophone mounting simplicityVSAvoidspeech signal quality

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The single microphone is divided into multiple microphones (at least three) arranged in a triangular configuration on the back surface of the mirror housing. This segmentation allows the system to overcome the blockage problem by using multiple sensing points while maintaining the integrated mirror mounting approach.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The microphones are positioned on the back surface of the mirror housing rather than inside the mirror support, utilizing the three-dimensional space available in the mirror assembly. This dimensional relocation allows direct sound path access while maintaining compact integration.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Adaptability or versatility

If omni-directional microphones are used to receive voice from all directions, then coverage is improved, but noise from all directions is also captured reducing signal-to-noise ratio

Engineering Contradiction:

Improvevoice reception coverageVSAvoidsignal-to-noise ratio

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

Instead of using omni-directional microphones with uniform sensitivity in all directions, the system employs directional processing that creates spatially selective response patterns. The triangular arrangement with DSP processing provides different sensitivity characteristics for different directions, enhancing speech signals while suppressing noise from specific directions.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The system converts the presence of multiple noise sources into a benefit by using the triangular microphone arrangement and DSP processing to identify and suppress noise from specific directions. The spatial distribution of microphones allows the system to distinguish between desired speech signals and unwanted noise, turning the challenge of multi-directional sound capture into an opportunity for directional noise suppression.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Device complexity

If conventional microphone arrangements are used, then device simplicity is maintained, but hands-free operation accuracy deteriorates in noisy vehicle environments

Engineering Contradiction:

Improvemicrophone assembly simplicityVSAvoidvoice recognition accuracy

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The system divides the microphone function into multiple transducers arranged in a triangular configuration, with each microphone contributing to the overall directional processing. This segmentation enables sophisticated noise suppression while maintaining a relatively simple integrated mirror assembly design.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system replaces complex mechanical directional microphone designs with an electrical/DSP-based directional processing approach. The triangular arrangement of omnirectional microphones combined with digital signal processing achieves directional selectivity without requiring mechanically complex directional microphone elements.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS8081772B2Vehicular microphone assembly using fractional power phase normalization

Publication Date: 2011.12.20 GENTEX CORP

AI summary

A triangular microphone assembly (101) for use in a vehicle accessory includes a mirror housing (106) adapted for attachment to the interior of the vehicle. A mirror is disposed in an opening of the mirror housing (106) and a plurality of virtual digital microphones (108a, 108b, 108c) are arranged in a substantially triangular configuration in the mirror housing (106). A digital signal processor (DSP) (537) is used for receiving signals from the plurality of digital microphones (108a, 108b, 108c) such that the digital microphones exhibit directional characteristics for reducing undesirable noise in at least one direction by normalizing the phase of the received signals as a function of signal frequency.