Microphone Directivity in Recessed Audio Housing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In audio conferencing apparatuses, the presence of a housing wall behind unidirectional microphones reduces their sensitivity and directivity due to sound reflection, leading to lowered performance.
Innovation Solution
The audio apparatus features a tub-shaped recessed part with microphones arranged inside, where each microphone's front side faces the bottom surface and its back side is directed higher than the wall, ensuring the direction opposite to its directivity is open acoustically, and may include a mesh steel sheet to further enhance this openness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If unidirectional microphones are arranged in a recessed part with directivity toward the center, then the microphones can collect sound from the front side, but the housing wall at the back side reflects sound and lowers sensitivity and directivity
Solution Approach 1:
The invention extracts the harmful reflective wall surface from the microphone's acoustic environment by creating an open acoustic space at the back side of the microphone, removing the source of sound reflection that degrades microphone performance
Solution Approach 2:
Instead of having the microphone face the center with the housing wall behind it (conventional arrangement), the invention inverts the arrangement by making the back side of the microphone acoustically open, allowing sound to reach the microphone from the front without being reflected by a rear wall
2Volume of moving object
If microphones are arranged in a recessed part on the housing, then the apparatus has a compact configuration, but the recessed part wall reduces microphone directivity
Solution Approach 1:
The invention applies different acoustic properties to different parts of the recessed structure: the front side maintains a closed recessed configuration for compactness, while the back side is made acoustically open to preserve microphone directivity, creating localized quality differences in the recessed part
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 maintains high directivity for unidirectional microphones even when embedded in a recessed part, reducing sound reflection and feedback, thereby improving sensitivity and reducing unwanted noise pickup.
Implementation Method 1
a wall surface of the recessed part of the housing exists at a rear side of each microphone (a direction opposite to a direction having a directivity). A unidirectional microphone has a sensitivity toward only its front side by combining a sound reaching from its back side and a sound reaching from its front side (a direction having a directivity) by means of level adjustment and phase adjustment. Thus, if a housing exists at the back side, the sound reaching from the front side reflects just at the back side, and the sensitivity with respect to the front side is lowered.
Implementation Method 2
a direction opposite to the direction having the directivity of each of the plurality of directional microphones is open acoustically. Namely, a front side of each microphone is directed toward a bottom surface of the recessed part, and its back side is directed toward a direction higher than the wall surface of the tub-shaped recessed part
Data Source
Figure 1(A)~1(C)
Figure 2(A)~2(B)
Figure 3
AI summary
The invention provides an audio apparatus which hardly causes a directivity to be lowered even in a case where a plurality of unidirectional microphones, each having a directivity toward a center of a housing of the apparatus, are embedded in a recessed part provided on an upper surface of the housing. Microphones 10A to 10P are disposed in the vicinity of a wall surface of a recessed part 13. Each of the microphones 10A to 10P is disposed so that its sound-collecting direction (a direction having a high directivity) corresponds to a center direction as viewed from an upper side of a housing 1. A direction (a rear side) opposite to the direction having the directivity of each of the plurality of directional microphones is open acoustically. Namely, a front side of each microphone directs toward an upper surface of the recessed part 13, and its back side directs toward a direction higher than the wall surface of the tub-shaped recessed part as viewed from a lateral side of the housing.