Sound Pickup Device Noise Isolation via Reference Microphone

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Solution Overview

Problem

Conventional sound pickup devices with porous exterior surfaces face challenges in mounting microphones effectively due to difficulties in molding recessed portions for microphone fixation, leading to noise contamination in audio signals from external sources.

Innovation Solution

The sound pickup device incorporates a configuration with a main microphone and a reference microphone disposed inside a housing with a porous exterior surface, utilizing support and blocking members to isolate the reference microphone from external sound pressure, allowing for efficient noise suppression by generating a noise-reduced audio signal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a porous exterior surface with multiple holes is used for sound pickup, then sound capture capability is improved, but noise contamination from external sources increases

Engineering Contradiction:

Improvesound capture capabilityVSAvoidnoise contamination

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The device divides the microphone system into two separate functional units: a main microphone for capturing external sound through the porous surface, and a reference microphone for detecting noise. This segmentation allows independent optimization of each microphone's function and position, enabling the main microphone to capture sound while the reference microphone monitors noise separately for subsequent cancellation processing

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The reference microphone acts as an intermediary that detects noise components in the environment. Its output is processed through an adaptive filter to generate a noise cancellation signal, which then subtracts the noise component from the main microphone's output. This intermediary approach enables indirect noise removal without directly interfering with the main sound capture path

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If microphones are mounted inside the housing, then protection from external elements is improved, but molding recessed portions for fixation becomes difficult

Engineering Contradiction:

Improveprotection from external elementsVSAvoidmolding complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The microphones are arranged in the depth dimension (Z-axis) inside the housing rather than requiring complex lateral recesses. The main microphone is positioned closer to the porous surface while the reference microphone is positioned deeper inside, allowing both to be mounted on a flat or simply contoured surface without requiring difficult multi-directional recessed portions

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Measurement precision

If the reference microphone is isolated from external sound, then noise detection accuracy is improved, but isolation structure complexity increases

Engineering Contradiction:

Improvenoise detection accuracyVSAvoidisolation structure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The housing structure serves multiple functions simultaneously: it provides mechanical protection for both microphones, defines the internal mounting positions, and acts as the isolation barrier for the reference microphone. By merging these functions into a single integrated housing component, the patent avoids adding separate isolation structures while still achieving effective noise detection

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

This configuration effectively reduces noise in audio signals picked up by the device, even with a porous exterior surface, enabling high-quality sound capture while allowing for easier microphone placement and housing molding.

Implementation Method 1

a housing (105) having a porous (a plurality of tone holes 114) exterior surface

Methodology Applied

Scientific EffectSound transmission through porous material: Porosity

Implementation Method 2

a second blocking member (116, 132, 134) that blocks between the outside of the housing and an inside of the reference microphone (111N), and a third blocking member (116, 132) that blocks the inside of the housing and the inside of the reference microphone (111N)

Methodology Applied

Scientific EffectAcoustic isolation: Physical Containment

Data Source

PatentEP3352473B1Sound pickup device and imaging device using same

Publication Date: 2019.07.24 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

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Figure 2A~2B
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AI summary

A sound pickup device includes a housing having a porous exterior surface, main microphones, a reference microphone disposed near the main microphones, a first support member, a second support member, a first blocking member that blocks between the inside of the housing and the insides of the main microphones, a second blocking member that blocks between the outside of housing and the inside of the reference microphone, and a third blocking member that blocks between the inside of the housing and the inside of the reference microphone.