Dual Microphone Sound Processing for Intermittent Noise Reduction
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Solution Overview
Problem
Conventional digital cameras struggle to accurately reduce noise from the sliding contact sound of a lens during autofocus and zoom operations, particularly intermittent driving noise and short-term noise, due to limitations in noise pattern acquisition.
Innovation Solution
A sound processing apparatus equipped with two microphones, one for environmental sounds and another for noise source sounds, along with a processor that performs Fourier transforms, noise data generation, and noise reduction, effectively detects and reduces short-term noise by adjusting the output magnitude.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a digital camera collects noise using a microphone to record sounds around the camera, then the sliding contact sound of the lens can be reduced, but the noise pattern acquisition becomes inaccurate for short-term noise and intermittent driving noise
Solution Approach 1:
The patent divides the noise reduction system into two separate microphone channels: one for collecting environmental sounds and another specifically for capturing lens driving noises. This segmentation allows each microphone to be optimized for its specific function, with the second microphone positioned to accurately capture short-term noise and intermittent driving noises from the lens motor, thereby resolving the contradiction between noise reduction effectiveness and measurement precision.
2Object-affected harmful factors
If the digital camera uses spectral subtraction method to reduce noise, then general sliding contact sound can be reduced, but short-term noise from intermittent driving and gear collision cannot be effectively reduced
Solution Approach 1:
The patent introduces a dedicated second microphone as an intermediary device specifically positioned to capture lens driving noises. This intermediary microphone provides accurate noise pattern data for short-term noise and intermittent driving noises, which is then used by the spectral subtraction method to effectively reduce these specific noise types, thereby improving reliability of short-term noise reduction while maintaining general sliding contact sound reduction.
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 apparatus effectively reduces short-term noise, improving the quality of recorded sound by accurately identifying and mitigating noise sources within the camera's housing.
Implementation Method 1
a first conversion unit configured to perform Fourier transform on a sound signal acquired by the first microphone to generate first sound data, a second conversion unit configured to perform Fourier transform on a sound signal acquired by the second microphone to generate second sound data
Implementation Method 2
a third conversion unit configured to perform inverse Fourier transform on sound data output from the second reduction unit
Data Source
AI summary
A sound processing apparatus includes a first microphone that acquires an environmental sound, a second microphone that acquires noise from a noise source, a first conversion unit that performs Fourier transform on a sound signal from the first microphone to generate first sound data, a second conversion unit that performs Fourier transform on a sound signal from the second microphone to generate second sound data, a first reduction unit that reduces noise from the noise source in the first sound data using noise data, a detection unit detects, based on the second sound data, that short-term noise from the noise source is included in the first sound data, a second reduction unit that controls a magnitude of sound data from the first reduction unit and reduces the short-term noise, and a third conversion unit that performs inverse Fourier transform on sound data from the second reduction unit.