Spherical Microphone Array for Omnidirectional Sound Collection
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Solution Overview
Problem
Conventional sound collection apparatuses require a large number of microphones to collect sound from all directions, and while increasing the distance between microphones improves accuracy, it also increases the apparatus size, leading to decreased resolution when the intervals are narrow.
Innovation Solution
A sound collection apparatus with a substantially spherical base featuring recess portions and microphones installed on the inner bottom surface, where the intervals between adjacent microphones are equal, allowing for accurate sound collection in all directions without enlarging the apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of microphones is increased to collect sound in all directions, then sound collection accuracy improves, but device complexity and size increase
Solution Approach 1:
The patent employs a spherical base structure with microphones arranged on its surface. This spherical geometry enables uniform 360-degree sound collection in all directions without requiring a large number of microphones. The curved surface naturally distributes the microphones optimally in three-dimensional space, improving spatial coverage and sound collection accuracy while maintaining a compact device configuration.
2Measurement precision
If the interval between adjacent microphones is increased to improve resolution, then estimation accuracy improves, but device size increases
Solution Approach 1:
The patent transitions from a two-dimensional planar arrangement to a three-dimensional spherical arrangement of microphones. By distributing microphones on the curved surface of a sphere, the system achieves larger effective intervals between adjacent microphones without increasing the overall device footprint. This three-dimensional spatial distribution improves phase difference measurement accuracy and sound source estimation while maintaining a compact apparatus size.
3Length of stationary object
If the interval between adjacent microphones is decreased to reduce device size, then device compactness improves, but phase difference measurement accuracy decreases
Solution Approach 1:
The spherical base structure allows microphones to be positioned with optimal spacing along the curved surface. The curvature of the sphere enables larger arc distances between adjacent microphones compared to planar arrangements of the same diameter, thereby maintaining adequate phase difference measurement accuracy while keeping the device compact. The three-dimensional spherical geometry maximizes the effective baseline for interferometric measurements within a small form factor.
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 enables accurate sound collection in all directions with a reduced number of microphones, improving resolution and reducing sound collection variation based on the arrival direction without increasing the apparatus size.
Implementation Method 1
N microphones 12-1 to 12-N are installed on inner bottom surface sides of the recess portions 111-1 to 111-N, respectively
Implementation Method 2
a substantially spherical base 11 on which at least N recess portions 111-1 to 111-N are provided in a surface thereof
Data Source
AI summary
A sound collection apparatus includes a substantially spherical base on which at least a predetermined number of recess portions are provided in a surface thereof with a predetermined interval therebetween; and a predetermined number of microphones. The predetermined number is an integer of 2 or greater. The microphones are installed on an inner bottom surface side of the recess portions one by one. Intervals between sound collecting portions of adjacent microphones are substantially equal to each other.