Acoustic Apparatus Using Bone Conduction Microphone for Voice Signal Isolation
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Solution Overview
Problem
Existing acoustic devices do not effectively reduce noise in the electrical signal corresponding to a user's voice, leading to suboptimal signal quality.
Innovation Solution
An acoustic device comprising a first microphone for receiving acoustic sound waves, a second microphone for bone conduction vibratory oscillations, and a processing unit that calculates a corrected electrical signal by subtracting ambient noise and osteophonic components from the combined signals from these microphones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single air-mounted microphone is used to capture the user's voice, then the device structure is simple, but the signal quality is degraded by ambient noise and osteophonic components
Solution Approach 1:
The patent divides the sound capture function into three separate microphones: an air-mounted microphone for acoustic sound waves, a bone-mounted microphone for osteophonic vibrations, and a noise-mounted microphone for ambient noise. Each microphone is segmented to capture specific sound components, allowing the processing unit to selectively combine and filter signals to improve overall signal quality while managing device complexity through functional specialization.
Solution Approach 2:
The patent combines signals from multiple microphones (air-mounted, bone-mounted, and noise-mounted) in the processing unit. By merging these distinct signal sources and applying computational processing to subtract noise and isolate the user's voice, the system achieves superior signal quality that cannot be obtained with a single microphone, while the integrated design manages the complexity of having multiple sensors.
2Measurement precision
If multiple microphones are used to reduce noise, then the signal quality is improved, but the device complexity increases
Solution Approach 1:
Each microphone is positioned and configured to capture specific local sound characteristics: the air-mounted microphone captures acoustic waves from the user's mouth area, the bone-mounted microphone captures osteophonic vibrations locally at the bone contact point, and the noise-mounted microphone captures ambient noise from the surrounding environment. This local quality approach allows each sensor to specialize in capturing specific sound components, improving noise reduction capability while justifying the multiple microphone configuration through their distinct local functions.
Solution Approach 2:
The processing unit implements feedback processing by continuously analyzing signals from all three microphones and dynamically adjusting the combined output. The system uses the noise-mounted microphone's ambient noise capture as feedback to subtract from the other signals, and uses the bone-mounted microphone's osteophonic signal as feedback to enhance low-frequency voice components. This feedback mechanism improves noise reduction capability while managing device complexity through intelligent signal processing rather than simply adding more hardware.
3Loss of information
If the bone-mounted microphone is used to capture low-frequency voice components, then the voice signal completeness is improved, but the osteophonic noise is also captured
Solution Approach 1:
The processing unit extracts and separates the useful low-frequency voice components from the osteophonic noise by analyzing the signal characteristics of the bone-mounted microphone. The system extracts the voice signal information while leaving behind the harmful osteophonic noise components, which are then removed through processing. This extraction approach allows the system to benefit from the bone-mounted microphone's ability to capture low-frequency voice components while eliminating the associated osteophonic noise, improving voice signal completeness without retaining the harmful factors.
Solution Approach 2:
The patent converts the harmful osteophonic noise into a beneficial signal source by using the bone-mounted microphone's unique ability to capture vibrations that complement the air-mounted microphone's acoustic capture. The osteophonic vibrations, though containing noise, provide valuable low-frequency voice components that are difficult to capture acoustically. The processing unit leverages this by combining the bone-mounted signal with the air-mounted signal, where the bone-mounted osteophonic components fill in missing low-frequency information while the processing removes the harmful noise, effectively converting a harmful factor into a beneficial contribution to overall voice signal completeness.
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
Significantly reduces ambient noise and osteophonic components, resulting in improved signal quality by isolating the user's voice component, enhancing voice clarity and reducing noise interference.
Implementation Method 1
a first microphone, the first microphone comprising a main electroacoustic transducer capable of receiving acoustic sound waves from a sound signal originating from the vocal cords and of transforming said acoustic waves into a first electrical signal
Implementation Method 2
a second microphone, the second microphone comprising a bone-excited mechanical transducer capable of receiving by bone conduction vibratory oscillations of said sound signal and of transforming said vibratory oscillations into a second electrical signal
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
This acoustic apparatus (10) comprises: a first microphone (12), the first microphone (12) comprising a principal electroacoustic transducer able to receive the acoustic sound waves of a sonic signal originating from the vocal cords and to convert said acoustic waves into a first electrical signal; a second microphone (14), the second microphone (14) comprising an osseous mechanical excitation transducer able to receive by osseous conduction vibratory oscillations of said sonic signal and to convert said vibratory oscillations into a second electrical signal; and means (48) for computing a corrected electrical signal depending on the first electrical signal and the second electrical signal, the corrected electrical signal being able to be delivered as output from the acoustic apparatus (10). The acoustic apparatus (10) furthermore comprises a noise reducing device (20), the noise reducing device (20) being connected at the output of the principal electroacoustic transducer in order to decrease the noise in the first electrical signal and the computing means (48) being connected, on the one hand, to the output of the noise reducing device (20), and on the other hand, to the output of the osseous mechanical excitation transducer.