Microphone System Frequency Band Gain Adjustment
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Solution Overview
Problem
Conventional microphones suffer from feedback issues and inadequate sound source discrimination, particularly in live music performances, due to their inability to effectively reject off-axis sounds and maintain uniform frequency response as the microphone distance from the source varies.
Innovation Solution
A microphone system using two or more spaced omni-directional transducers that process signals through frequency band separation and relative gain adjustment based on distance and angle thresholds, emphasizing desired sound sources while rejecting unwanted noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional microphones with directional acceptance patterns are used to reject off-axis sounds, then feedback tendency is reduced, but sound source discrimination capability is insufficient
Solution Approach 1:
The patent divides the sound field into multiple frequency bands and processes each band separately with different gain settings. By segmenting the audio signal into frequency components, the system can selectively emphasize or reject specific sound sources based on their spectral characteristics, thereby improving sound source discrimination beyond what a single directional pattern can achieve.
Solution Approach 2:
The patent transitions from spatial filtering alone (directional microphone patterns) to a combined approach that incorporates frequency-domain filtering. By adding the frequency dimension to the spatial filtering approach, the system achieves superior sound source discrimination capability while maintaining feedback rejection.
2Measurement precision
If omni-directional microphones are used to capture all sounds, then sound capture capability is improved, but feedback susceptibility increases
Solution Approach 1:
The patent applies segmentation by dividing the omnidirectional sound capture into multiple frequency bands, then applying different gain treatments to each band. This allows the system to maintain comprehensive sound capture while selectively attenuating frequencies that contribute to feedback, thus resolving the contradiction between capture capability and feedback susceptibility.
Solution Approach 2:
The patent changes the gain parameter dynamically based on frequency band and detected sound source characteristics. By adjusting gain settings across different frequency bands, the system maintains high sound capture capability for desired sources while reducing gain for frequencies prone to feedback, thereby reducing overall feedback susceptibility.
3Object-affected harmful factors
If pressure gradient responding microphones are used to achieve directional response, then off-axis sound rejection is improved, but frequency response uniformity deteriorates due to proximity effect
Solution Approach 1:
The patent segments the frequency response into multiple bands and applies independent gain control to each band. This compensation approach counteracts the proximity effect by boosting high frequencies when the microphone is close to the sound source, thereby maintaining frequency response uniformity across different distances while preserving the directional rejection benefits.
Solution Approach 2:
The patent dynamically changes gain parameters across frequency bands based on the detected distance to the sound source. This allows the system to maintain off-axis sound rejection capability while compensating for proximity effect-induced frequency response variations, achieving both goals simultaneously.
Data Source
AI summary
A method of distinguishing sound sources includes the step of transforming data, collected by at least two transducers which each react to a characteristic of an acoustic wave, into signals for each transducer location. The transducers are separated by a distance of less than about 70 mm or greater than about 90 mm. The signals are separated into a plurality of frequency bands for each transducer location. For each band a comparison is made of the relationship of the magnitudes of the signals for the transducer locations with a threshold value. A relative gain change is caused between those frequency bands whose magnitude relationship falls on one side of the threshold value and those frequency bands whose magnitude relationship falls on the other side of the threshold value. As such, sound sources are discriminated from each other based, on their distance from the transducers.