Noise Extraction Device Using Microphone Directivity Synthesis

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Solution Overview

Problem

Conventional microphone devices using two or more units to address vibration noise face challenges due to differing vibration noise signals and sensitivity levels between microphone units, leading to incomplete noise cancellation and the need for additional vibration sensors.

Innovation Solution

A noise extraction device employing directivity synthesis units with different sensitivities to noise and sound pressure, and an acoustic cancellation unit to subtract noise components from directionally synthesized signals, allowing precise extraction of vibration noise without additional sensors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If the directivity synthesis method is used to form directivity on a small scale, then directivity can be formed, but the sensitivity to sound pressure is reduced and vibration noise becomes more serious

Engineering Contradiction:

Improvedirectivity patternVSAvoidsensitivity to sound pressure

Core Design Contradiction:

ShapeVSMeasurement precision

Solution Approach 1:

The patent applies local quality by creating different directivity patterns for different microphone units. The first microphone unit has a first directivity pattern optimized for sound pressure sensitivity, while the second microphone unit has a second directivity pattern optimized for vibration noise detection. This allows each microphone unit to have specialized local characteristics suited to its specific function, resolving the contradiction between forming directivity and maintaining sound pressure sensitivity.

Inventive Principle:

Principle #3Local quality

2Reliability

If separate vibration sensors are added to cancel vibration noise, then vibration noise can be cancelled, but device complexity increases

Engineering Contradiction:

Improvevibration noise cancellationVSAvoidnumber of sensors

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements multi-functionality by enabling the microphone units to serve dual purposes. The first microphone unit functions as both a sound wave pickup device and a vibration sensor. The second microphone unit similarly serves as both a reference device and a vibration sensor. This eliminates the need for separate dedicated vibration sensors, reducing device complexity while maintaining vibration noise cancellation capability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent applies self-service by having the microphone units themselves perform the vibration noise cancellation function through their own signal processing. The vibration noise is extracted from the signals of the first and second microphone units using directivity synthesis, and then used to cancel vibration noise in the original sound wave signals. This self-contained approach eliminates the need for external vibration sensors.

Inventive Principle:

Principle #25Self-service

3Ease of manufacture

If the same directivity synthesis is applied to all microphone units, then processing is simplified, but vibration noise cancellation becomes ineffective due to individual variability in vibration sensitivity

Engineering Contradiction:

Improveprocessing simplicityVSAvoidvibration noise cancellation accuracy

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

Inventive Principle:

Principle #3Local quality

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

The solution enables precise extraction and cancellation of vibration noise, improving microphone resistance to vibration and wind noise, allowing the device to function as both a microphone and vibration sensor without additional hardware.

Implementation Method 1

a directivity synthesis method of a sound-pressure gradient type

Methodology Applied

Scientific EffectSound pressure gradient: Pressure Gradient

Implementation Method 2

an acoustic cancellation unit which cancels an acoustic component of one of the two directionally synthesized signals by subtracting the one of the two directionally synthesized signals from the other of the two directionally synthesized signals

Methodology Applied

Scientific EffectSignal subtraction:

Implementation Method 3

first and second microphone units which each pick up a sound

Methodology Applied

Scientific EffectMicrophone transduction:

Data Source

PatentUS8311236B2Noise extraction device using microphone

Publication Date: 2012.11.13 PANASONIC HOLDINGS CORP

AI summary

A noise extraction device of the present invention includes: first and second microphone units (11 and 12) each picking up a sound; a directivity synthesis unit which performs a directivity synthesis on output signals respectively received from the first and second microphone units (11 and 12) and generates two directionally synthesized signals which have: different sensitivities to noise; the same directional pattern with respect to sound pressure; and the same effective acoustic center position; and an acoustic cancellation unit which cancels an acoustic component of one of the two directionally synthesized signals by subtracting the one of the two directionally synthesized signals from the other of the two directionally synthesized signal, so as to extract a noise component.