Multiple Sound Source Microphone Directivity Testing via Wave Interference

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Solution Overview

Problem

Existing methods for measuring microphone directivity require a large test environment due to significant amplitude differences when the microphone is placed close to a single point sound source, leading to inaccurate measurements.

Innovation Solution

A directivity measurement method and device using multiple sound sources, where sound waves from two or more sound sources overlap and interfere, allowing directivity measurement at a closer distance by ensuring consistent amplitude and frequency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If the microphone is placed close to a single point sound source to reduce test environment size, then the test environment size is reduced, but the amplitude difference between front and rear openings becomes excessive causing measurement inaccuracy

Engineering Contradiction:

Improvetest environment sizeVSAvoiddirectivity measurement accuracy

Core Design Contradiction:

Area of stationary objectVSMeasurement precision

Solution Approach 1:

The patent divides a single point sound source into multiple sound sources (at least two) arranged in specific spatial positions. This segmentation allows the microphone to be placed closer to the sound sources while maintaining consistent acoustic pressure conditions, thereby reducing test environment size without compromising measurement accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent combines multiple sound sources to create a composite acoustic field where the sound waves from different sources overlap and interfere constructively at the microphone position. This merging of sound sources produces a stable acoustic environment that enables accurate directivity measurement at close distances.

Inventive Principle:

Principle #5Merging (Combining)

2Measurement precision

If the microphone is placed far away from the sound source to ensure consistent amplitude, then measurement accuracy is improved, but the test environment size increases

Engineering Contradiction:

Improvedirectivity measurement accuracyVSAvoidtest environment size

Core Design Contradiction:

Measurement precisionVSArea of stationary object

Solution Approach 1:

By segmenting the acoustic source into multiple distributed sound sources, the patent creates a localized acoustic field that maintains consistent amplitude characteristics at close distances, eliminating the need for large separation distances while preserving measurement accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the spatial arrangement and distribution parameters of the sound sources, positioning them at specific distances and angles relative to the microphone. This parameter optimization allows accurate measurement at reduced distances by controlling the acoustic field characteristics.

Inventive Principle:

Principle #35Parameter changes

3Area of stationary object

If multiple sound sources are used to enable close-distance measurement, then test environment size is reduced, but device complexity increases

Engineering Contradiction:

Improvetest environment sizeVSAvoidmeasurement system complexity

Core Design Contradiction:

Area of stationary objectVSDevice complexity

Solution Approach 1:

The patent designs the multiple sound sources to serve dual functions: they collectively create the acoustic field for directivity measurement while individually acting as point sources for calibration purposes. This multi-functionality reduces the need for separate calibration equipment, offsetting the increased complexity of having multiple sound sources.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

Enables accurate directivity measurement of microphones in a smaller environment by minimizing amplitude differences through overlapping and interfering sound waves, reducing the required distance to 10 cm or less from each sound source.

Implementation Method 1

a first sound wave generated by the first sound source overlaps and interferes with a second sound wave generated by the second sound source

Methodology Applied

Scientific EffectSound wave interference: Interference

Data Source

PatentUS20250310712A1Directivity measurement method and device for a multiple sound source microphone

Publication Date: 2025.10.02 LANTO ELECTRONIC LIMITED

AI summary

A directivity measurement method and device for a multiple sound source microphone is disclosed, wherein a first sound wave generated by a first sound source overlaps and interferes with a second sound wave generated by a second sound source, and a transmission range of the first and second sound waves encompasses a measurement position. Because the first sound wave of the first sound source and the second sound wave of the second sound source overlap and interfere with each other, the intensity of the amplitude of the overlapped and interfered with first and second sound waves, while smoothly varying, is obtained at a position closer to the first sound source and the second sound source. Therefore, the directivity of a microphone to be tested can effectively and accurately be measured even if the microphone to be tested is placed close to the first sound source and the second sound source.