Microphone Gain Control Using Band-Split Sound Distance Cues
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Solution Overview
Problem
Existing sound pickup devices face challenges in accurately determining the distance of a sound source from a microphone due to environmental factors, particularly with reflected sounds, leading to estimation errors and difficulties in distinguishing direct and indirect sounds.
Innovation Solution
A sound pickup device incorporating a microphone, an acoustic obstacle, and a signal processor that splits sound signals into multiple bands, compares characteristic amounts, and adjusts gain based on these comparisons to block unwanted sound pickup ranges, thereby reducing reliance on reflected sounds for distance estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If reflected sound is used for distance estimation, then sound pickup can be performed, but environment causes error in distance estimation
Solution Approach 1:
The sound signal is segmented into multiple frequency bands, and the system selectively processes signals from different bands based on their characteristics. Direct sound and reflected sound have different frequency distribution characteristics, allowing the system to segment and identify them separately, thereby improving distance estimation accuracy while reducing environmental interference.
Solution Approach 2:
The system changes the parameter of frequency band selection dynamically. By adjusting which frequency bands are used for processing based on the detected sound characteristics, the system can optimize distance estimation accuracy for different environmental conditions, reducing the harmful effect of reflected sounds.
2Measurement precision
If arrival time difference between direct sound and reflected sound is used, then distance can be estimated, but it becomes difficult to estimate distance when sounds from same direction have same arrival time difference
Solution Approach 1:
The system segments the sound signal into multiple frequency bands and analyzes the spectral characteristics of each band. Direct sound and reflected sound exhibit different spectral patterns, allowing the system to distinguish them through frequency-domain analysis rather than relying solely on time-domain arrival differences, thereby improving distance estimation accuracy.
Solution Approach 2:
The system replaces the mechanical time-based detection method with spectral analysis in the frequency domain. By using Fast Fourier Transform (FFT) to convert time-domain signals into frequency-domain representations, the system can identify direct and reflected sounds through their spectral characteristics, overcoming the limitation of identical arrival time differences.
3Quantity of substance
If gain is increased to capture distant sound, then sound from distant sources can be acquired, but noise from remote areas increases
Solution Approach 1:
The system applies different gain adjustments to different frequency bands based on their local characteristics. Frequency bands containing direct sound are amplified with higher gain, while bands dominated by reflected sound or noise receive lower gain, thereby capturing distant sound effectively while suppressing noise from remote areas.
Solution Approach 2:
The system dynamically changes the gain parameter for each frequency band based on the detected sound characteristics. By adjusting the gain parameter selectively rather than uniformly across all frequencies, the system can enhance distant sound signals while minimizing the amplification of noise, improving the signal-to-noise ratio.
Data Source
AI summary
A sound pickup method includes splitting a sound pickup signal of a microphone of which sound pickup in a predetermined range is blocked by an acoustic obstacle, into a plurality of sound pickup signals and subjecting at least one sound pickup signal among the plurality of sound pickup signals to band limitation processing, and comparing characteristic amounts of the plurality of sound pickup signals including the sound pickup signal after being subjected to the band limitation processing and controlling a gain of the microphone in accordance with a result of comparing the characteristic amounts.