Overhead Microphone Assembly Using Beamforming for Noise Rejection
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Solution Overview
Problem
Conventional microphones, such as omni-directional and cardioid microphones, face challenges in audio and video conferencing applications due to their inability to effectively reject reverberation and noise, leading to poor sound quality and inconvenient placement requirements, which complicates conference settings and limits coverage area.
Innovation Solution
A microphone assembly utilizing multiple unidirectional microphone elements installed overhead, with a microphone steering processor that dynamically mixes and gates signals to optimize signal-to-noise ratio, allowing for wide-area coverage and scalable configurations, while minimizing interference and maintaining high sound quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If an omni-directional microphone is used to gather sound from all directions, then coverage area is improved, but sound quality deteriorates due to inability to reject reverberation and noise
Solution Approach 1:
The patent divides the microphone system into multiple unidirectional microphone elements arranged in a specific geometry (e.g., tetrahedral configuration with four elements). Each element has a defined pickup direction, and through electronic beam forming and signal processing, the system achieves both wide coverage and noise rejection by selectively combining signals from different elements based on the direction of interest.
2Reliability
If a cardioid microphone is used to reject noise from other directions, then sound quality is improved, but coverage area deteriorates to a very small area
Solution Approach 1:
The patent combines multiple unidirectional microphone elements with different pickup orientations into a single integrated system. By electronically merging the outputs of these elements through beam forming techniques, the system achieves the noise rejection characteristics of directional microphones while extending the effective coverage area to encompass the entire conference room volume.
Solution Approach 2:
The patent transitions from a single-directional pickup approach to a three-dimensional array configuration. The microphone elements are positioned in space (e.g., tetrahedral arrangement) to capture sound from multiple directions simultaneously, adding spatial dimensionality to the pickup pattern and enabling both wide coverage and directional selectivity.
3Area of stationary object
If several cardioid microphones are connected simultaneously to cover more participants, then coverage area is improved, but device complexity increases and the room becomes cluttered
Solution Approach 1:
The patent creates a universal microphone system that can serve multiple participants simultaneously through a single overhead installation. The multi-element array with electronic beam forming provides omnidirectional coverage and can dynamically focus on different speakers without requiring physical reconfiguration or multiple separate microphone units, thereby reducing overall system complexity.
4Area of stationary object
If microphones are placed on conference tables for each participant, then coverage area is improved, but ease of operation deteriorates as participants must speak into specific microphones
Solution Approach 1:
The overhead microphone system with electronic beam forming automatically tracks and follows the active speaker without requiring participant action. The system self-adjusts by detecting the direction of speech and dynamically focusing on the current speaker, eliminating the need for participants to consciously direct their speech toward specific microphones or to manually select which microphone to use.
Data Source
AI summary
An overhead microphone assembly using multiple unidirectional microphone elements. The microphone assembly is installed overhead, generally above all the desired sound sources and below the undesired sound sources. The signals from these multiple microphone elements are fed into a microphone steering processor which can mix and gate the signals to ensure the best signal/noise ratio. The steering processor may also track the sound source dynamically when such tracking (source locating) is desired. The resulting audio signal from the steering processor may be further processed, such as echo canceling, noise reduction and automatic gain control.