Dual-Microphone Beamforming for Front-Rear Audio Balance
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Solution Overview
Problem
Portable electronic devices with multimedia capabilities face challenges in balancing audio levels between the operator and subject during recording, as the operator's audio often overpowers the subject due to their closer proximity to the microphones, especially with omnidirectional microphone capsules.
Innovation Solution
The implementation of an electronic apparatus with a rear-side and front-side microphone configuration, where an automated balance controller generates a balancing signal based on an imaging signal to process the audio signals and adjust the gain levels, ensuring the operator's audio does not overpower the subject's audio by using beamforming techniques to create directional patterns that emphasize the subject's audio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If omnidirectional microphones are used to record both operator and subject, then audio information from all directions can be captured, but the operator's audio overpowers the subject's audio due to proximity
Solution Approach 1:
The patent divides the audio capture function into two separate microphones: a front-side microphone for capturing subject audio and a rear-side microphone for capturing operator audio. This segmentation allows independent control of audio levels from different directions, resolving the imbalance problem where the operator's proximity causes their audio to overpower the subject's audio.
Solution Approach 2:
The patent applies different gain characteristics to different spatial zones: front-side gain for subject direction and rear-side gain for operator direction. By making the gain structure directionally dependent rather than uniform, the system achieves appropriate audio level balance for each spatial region while maintaining omnidirectional capture capability.
2Ease of operation
If the operator is positioned close to the device for convenient operation, then ease of use is improved, but the operator's audio level becomes too high relative to the subject
Solution Approach 1:
The patent implements directionally dependent gain control where the rear-side microphone (capturing operator audio) has different gain characteristics compared to the front-side microphone (capturing subject audio). This allows the system to accommodate close operator positioning for ease of use while compensating for the resulting audio level imbalance through differential gain adjustment.
Solution Approach 2:
The system dynamically adjusts the gain parameter based on the spatial origin of the audio signal. By changing the gain parameter differently for front-side and rear-side microphones, the system maintains appropriate audio level balance even when the operator is positioned close to the device for convenient operation.
3Device complexity
If a single microphone is used to reduce device complexity, then the device structure is simplified, but the ability to balance audio levels from different directions is lost
Solution Approach 1:
Instead of using a single omnidirectional microphone, the patent segments the audio capture function into two dedicated microphones: one for front-side (subject) audio and one for rear-side (operator) audio. This segmentation enables independent gain control for each direction, providing the directional audio control capability that a single microphone cannot achieve.
Solution Approach 2:
The dual-microphone configuration serves multiple functions: it captures audio from different directions simultaneously, enables independent gain control for each direction, and maintains a relatively simple device structure. This multi-functionality approach resolves the contradiction by achieving directional control without excessive complexity.
Data Source
AI summary
An electronic apparatus is provided that has a rear-side and a front-side, a first microphone that generates a first signal, and a second microphone that generates a second signal. An automated balance controller generates a balancing signal based on an imaging signal. A processor processes the first and second signals to generate at least one beamformed audio signal, where an audio level difference between a front-side gain and a rear-side gain of the beamformed audio signal is controlled during processing based on the balancing signal.