Sound Processing Apparatus Phase Correction
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Solution Overview
Problem
Existing sound processing apparatuses face challenges in correcting sensitivity differences between microphones, leading to variations in directivity and increased production costs, as well as difficulties in maintaining consistent characteristics over time due to aging.
Innovation Solution
The apparatus transforms sound signals from multiple microphones into the frequency domain, calculates spectral ratios, and derives phase correction values to adjust for phase differences, allowing for the correction of sensitivity variations between microphones, thereby reducing the impact of individual microphone differences on directivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If teacher signals generated at a position equidistantly located from a plurality of microphones are used to adjust microphone sensitivities, then microphone sensitivity matching is improved, but production cost increases and the method cannot correct characteristic alterations over time
Solution Approach 1:
The system uses the microphones themselves to generate correction signals by capturing ambient sound fields, eliminating the need for external teacher signals or equidistant positioning. Each microphone contributes to its own correction through spectral ratio calculations against a reference microphone, making the system self-calibrating without additional manufacturing complexity
Solution Approach 2:
The invention changes the approach from physical positioning parameters (equidistant location) to spectral domain parameters (frequency-based spectral ratios). By operating in the frequency domain rather than spatial domain, the system achieves sensitivity matching without requiring precise physical positioning or additional manufacturing steps
2Manufacturing precision
If teacher signals generated at a position equidistantly located from a plurality of microphones are used to adjust microphone sensitivities, then microphone sensitivity matching is improved, but the method cannot correct characteristic alterations over time after shipment
Solution Approach 1:
The system continuously calculates spectral ratios between microphones and applies real-time phase correction based on these ratios. This ongoing feedback mechanism allows the system to adapt to characteristic alterations over time, correcting sensitivity mismatches that develop during aging without requiring re-adjustment
Solution Approach 2:
The invention establishes a reference microphone that serves as a stable baseline for all other microphones. This preliminary designation of a reference creates a framework for continuous correction, enabling the system to maintain sensitivity matching throughout its operational life by constantly comparing against this reference
3Stability of the object's composition
If microphones with the same sensitivity are used to achieve desired directivity characteristics, then directivity stability is improved, but individual differences between microphones still cause directivity variation
Solution Approach 1:
The invention replaces the mechanical approach of selecting and matching microphones during manufacturing with a signal processing approach. By using spectral ratio calculations and phase correction in the frequency domain, the system compensates for individual microphone differences through electronic means rather than physical selection
Solution Approach 2:
The system transforms the problem from the time domain to the frequency domain by applying Fourier transforms. This parameter change allows spectral ratios to be calculated, revealing frequency-dependent sensitivity differences that can then be corrected through phase adjustment, achieving directivity stability without requiring perfectly matched microphones
Data Source
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AI summary
There is provided a sound processing apparatus (1) for processing received sounds. A plurality of sound receiving units (14a, 14b) which are included in the apparatus output individually a sound signal corresponding to a received sound, then the sound signals in a time domain are converted into respective converted signals in a frequency domain, and a spectral ratio between the two converted signals is calculated for driving a phase correction value which corrects a phase of the sound signal. The sound receiving units may, for example, be microphones of a mobile telephone.