Dual-Microphone Audio Capture for Shadowing and Comb Filtering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Acoustic obstructions, such as laptop computers, cause quality degradation in audio signals during teleconferencing by introducing shadowing and comb filtering effects, which affect sound pickup and transmission.
Innovation Solution
A dual-microphone system is employed, with one microphone arranged close to the surface and another elevated above the obstruction, using low pass and high pass filters to combine signals and reduce these effects, along with optional toroid microphone configurations and time delays to enhance audio quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single microphone is placed on the table surface for easy installation and coverage, then installation simplicity and coverage are improved, but audio quality degrades due to shadowing effects from acoustic obstructions
Solution Approach 1:
The patent divides the audio capture function into two separate microphones positioned at different heights. The first microphone is placed on the table surface for easy installation and coverage, while the second microphone is elevated above the obstruction to capture high-frequency sounds that would otherwise be blocked. This segmentation allows each microphone to specialize in different frequency ranges, resolving the contradiction between installation simplicity and audio quality.
Solution Approach 2:
The patent introduces a vertical dimension to the microphone arrangement by positioning one microphone above the acoustic obstruction. This dimensional change allows the system to capture sounds from different spatial perspectives, specifically enabling the elevated microphone to receive high-frequency sounds that diffract over the obstruction while the table-level microphone captures lower frequencies, thereby improving overall audio quality without compromising installation ease.
2Area of stationary object
If microphones are placed on the table surface for coverage, then coverage area is improved, but sound quality worsens due to acoustic obstructions blocking the sound path
Solution Approach 1:
The patent segments the audio capture function across two microphones at different heights. The table-level microphone maintains wide coverage area while the elevated microphone specifically captures high-frequency sounds that would be blocked by obstructions. This segmentation allows the system to preserve coverage area while improving sound quality through frequency-based division of labor.
Solution Approach 2:
The patent applies local quality by assigning different functional characteristics to microphones at different positions. The table-level microphone is optimized for coverage and lower frequencies, while the elevated microphone is specifically positioned to capture high-frequency sounds that diffract over obstructions. This local optimization of microphone placement and frequency response resolves the contradiction between coverage area and sound quality.
3Adaptability or versatility
If acoustic obstructions are present in the sound path, then device placement flexibility is improved, but audio signal quality deteriorates due to shadowing and comb filtering effects
Solution Approach 1:
The patent converts the harmful shadowing effect of acoustic obstructions into a beneficial frequency separation mechanism. By positioning one microphone above the obstruction, the system exploits the fact that high-frequency sounds diffract over the obstruction while lower frequencies are blocked. This transforms the obstruction from a purely harmful element into a natural frequency filter, allowing the elevated microphone to capture high frequencies that would otherwise be mixed with blocked low frequencies at the table level.
Solution Approach 2:
The patent resolves the conflict between placement flexibility and audio quality by adding a vertical dimension to the microphone arrangement. This allows the system to accommodate acoustic obstructions in the horizontal plane while maintaining audio quality through the elevated microphone position, thereby preserving device placement flexibility without sacrificing signal 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 system effectively minimizes shadowing and comb filtering artifacts, improving sound quality by handling different frequency ranges and reducing subjective distortions, resulting in clearer and more intelligible audio transmission.
Implementation Method 1
processing a signal provided by the first microphone using a low pass filter
Implementation Method 2
processing a signal provided by the second microphone using a high pass filter
Data Source
AI summary
A method and system for obtaining an audio signal. In one embodiment, the method comprises receiving a first sound signal at a first microphone arranged at a first height vertically above a substantially flat surface; receiving a second sound signal at a second microphone arranged at a second height vertically above the substantially flat surface; processing a signal provided by the first microphone using a low pass filter; processing a signal provided by the second microphone using a high pass filter; adding the signals processed by the low pass filter and the high pass filter to form a sum signal; and outputting the sum signal as an audio signal.