Multi-microphone Noise Floor Mitigation via Frequency Splicing
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Solution Overview
Problem
Image capture devices face performance and user experience issues due to microphone noise floors, which introduce audible tones and artifacts, particularly affecting audio quality during speech recording.
Innovation Solution
A method and apparatus that combine noise floor signals from multiple microphones, where a front microphone with minimal diffraction effects is used as the default for capturing audio without diffraction, and a rear microphone's clean noise floor is spliced with the front microphone's signal at a defined frequency point to mitigate noise and diffraction effects, generating a substantially clean audio signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a front microphone is used to capture audio, then diffraction effects are minimized, but the noise floor becomes noisy with audible tones and artifacts
Solution Approach 1:
The audio frequency spectrum is segmented into multiple frequency bins, allowing different portions of the spectrum to be processed differently. The noise floor mitigation is applied selectively to specific frequency ranges where the front microphone exhibits noisy characteristics, while preserving the clean diffraction-free audio in other frequency ranges.
Solution Approach 2:
Different quality characteristics are applied to different frequency portions of the audio signal. The rear microphone's noise floor characteristics are utilized for frequencies where the front microphone performs poorly, while the front microphone's diffraction-free characteristics are preserved for frequencies where it performs well.
2Object-generated harmful factors
If a rear microphone is used to capture audio, then the noise floor is clean, but diffraction effects increase due to device structure
Solution Approach 1:
The audio signal is divided into frequency bins, enabling selective application of rear microphone audio only in frequency ranges where it provides clean noise floor characteristics without introducing excessive diffraction artifacts.
Solution Approach 2:
The patent combines audio signals from both front and rear microphones by frequency binning, selecting the best source for each frequency range. This merging approach leverages the strengths of both microphones while mitigating their respective weaknesses.
3Object-generated harmful factors
If multiple microphones are combined to mitigate noise floor, then audio quality improves, but device complexity increases
Solution Approach 1:
The patent replaces complex hardware solutions with signal processing techniques. Instead of using additional microphones or complex acoustic structures, the solution uses frequency binning and digital signal processing to mitigate noise floor effects, reducing mechanical complexity while maintaining audio quality.
Data Source
AI summary
An image capture device reduces noise floor using multiple microphones. The image capture device includes a processor that obtains a front microphone signal from a front microphone, the front microphone signal having a noisy noise floor portion, obtains a rear microphone signal from a rear microphone, sets a splice point based on mitigation of the noisy noise floor portion relative to a speech frequency range, and combines a substantially clean noise floor portion of the rear microphone signal at or below the splice point with a remaining portion of the front microphone signal above the splice point to generate a microphone signal.