Stereo Audio Noise Suppression Using Dual Microphones and Spectral Subtraction
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Solution Overview
Problem
Existing audio processing techniques in image capturing devices face challenges in effectively isolating and removing driving noise from surrounding environment sound, particularly in stereo audio recording, due to the need for additional microphones which increase costs and complexity.
Innovation Solution
An audio processing apparatus with a main microphone for capturing surrounding environment sound and a sub microphone for capturing driving noise, using a transform unit to generate frequency spectrum data and a driving noise computation processing unit to suppress driving noise, allowing for effective noise reduction without the need for additional microphones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a second microphone is added to capture driving noise separately, then driving noise can be effectively removed from audio signals, but device complexity and cost increase
Solution Approach 1:
The patent makes the first microphone perform dual functions: capturing both surrounding environment sound and driving noise. By strategically positioning the first microphone to face the driving unit, the system enables one microphone to serve multiple purposes, eliminating the need for a dedicated second microphone for noise capture while maintaining effective noise removal capability
Solution Approach 2:
The patent combines the functions of capturing environment sound and driving noise into a single first microphone. Instead of using separate microphones for these two functions, the system merges them into one component, thereby reducing device complexity and cost while still enabling effective driving noise removal through spectral subtraction
2Ease of manufacture
If spectral subtraction is performed using a single noise profile, then processing is simplified, but noise removal accuracy decreases because driving signals vary between products
Solution Approach 1:
The patent performs preliminary action by capturing driving noise signals during a test run before actual product deployment. This preliminary noise capture allows the system to create an accurate noise profile specific to each product's driving unit characteristics, ensuring high noise removal accuracy without requiring complex real-time adjustments during operation
Solution Approach 2:
The patent changes the approach from using a generic noise profile to capturing product-specific noise characteristics during test runs. By adjusting the noise capture process to record actual driving noise from each specific product's driving unit, the system achieves accurate noise removal tailored to individual product variations while maintaining simple processing
3Measurement precision
If three microphones are used for stereo audio recording with noise detection, then stereo audio quality can be maintained with noise removal, but cost and surface area requirements increase
Solution Approach 1:
The patent makes the first microphone universal by having it capture both stereo environment sound and driving noise simultaneously through strategic positioning. This multi-functional approach allows the microphone to serve dual purposes without requiring additional components, thereby maintaining stereo audio quality while reducing the total microphone count from three to two
Solution Approach 2:
The patent merges the noise capture function into the existing first microphone used for stereo recording. Instead of adding a separate third microphone for noise detection, the system combines these functions in one component, reducing the microphone quantity from three to two while maintaining both stereo audio quality and effective noise removal
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables efficient suppression of driving noise in both left and right channels of stereo audio, improving audio quality without the need for additional microphones, thus reducing costs and complexity while maintaining effective noise reduction.
Implementation Method 1
frequency spectrum data is generated by applying a Fast Fourier Transform to time-series audio data obtained from a microphone
Implementation Method 2
The result of this subtraction is then subjected to an inverse Fast Fourier Transform (iFFT) to generate time-series audio data with the noise removed
Data Source
AI summary
An audio processing apparatus includes a transform unit that transforms time series audio data obtained from first and second microphones into first and second frequency spectrum data; a driving noise computation processing unit that computes a subtraction amount of the driving noise for each of frequencies from the first and second frequency spectrum data obtained by the transform unit; a generating unit that, on the basis of the first and the second frequency spectrum data obtained by the transform unit and the driving noise subtraction amount obtained by the driving noise computation processing unit, generates left and right channel frequency spectrum data in which the driving noise is respectively suppressed; and an inverse transform unit that inverse-transforms the left and right channel frequency spectrum data generated by the generating unit into left and right channel time series audio data, respectively.