Wired and Wireless Microphone Arrays for Phase-Shift Noise Control
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Solution Overview
Problem
Existing noise-canceling microphones require close proximity to the sound source, leading to phase shifts at higher frequencies and reduced effectiveness, and the use of microphone arrays is hindered by clutter and unreliability of extra cables.
Innovation Solution
Utilizing incidental microphones in conjunction with a principal microphone through short-range wireless links, such as Bluetooth, to jointly process audio signals for enhanced noise reduction without additional microphones or cables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If noise-canceling microphone operates with close proximity to sound source, then signal-to-noise ratio is improved, but phase shifts occur at higher frequencies causing loss of discrimination above 1 KHz
Solution Approach 1:
The patent segments the audio frequency range into multiple sub-bands and processes each sub-band separately using different microphone pairs. This allows optimal noise cancellation for each frequency range without the phase shift problems that would occur if a single microphone pair tried to handle all frequencies simultaneously.
Solution Approach 2:
The patent transitions from a single-microphone approach to a multi-microphone array approach, adding the spatial dimension to the noise cancellation process. By using multiple microphones at different positions and combining their signals through digital signal processing, the system achieves both close-proximity signal capture and effective high-frequency discrimination.
2Measurement precision
If microphone arrays are used with widely spaced microphones, then noise reduction effectiveness is improved, but device size increases becoming larger than modern mobile phones
Solution Approach 1:
The patent divides the audio spectrum into multiple sub-bands and assigns different microphone pairs to different sub-bands. This segmentation allows the system to achieve effective noise reduction across all frequencies without requiring all microphones to be widely spaced, as each sub-band can use optimally spaced microphones for its frequency range.
Solution Approach 2:
The patent makes the mobile phone's existing microphone system multi-functional by having it serve both as a single-microphone recorder and as part of a multi-microphone array for noise cancellation. The incidental microphones in the headset are activated to provide signals that are processed jointly with the principal microphone, eliminating the need for additional dedicated microphones.
3Measurement precision
If multiple microphones are used in array configuration, then noise reduction capability is improved, but clutter and unreliability of extra cables becomes a nuisance
Solution Approach 1:
The patent replaces the mechanical cable connection system with a wireless communication system. The mobile phone and headset microphone communicate audio signals wirelessly, eliminating the need for physical cables connecting multiple microphones to a central processing unit. This substitution removes the clutter and reliability issues associated with cable connections while maintaining the multi-microphone array functionality.
Solution Approach 2:
The patent uses wireless communication as an intermediary between the microphones and the signal processing system. Instead of direct cable connections, audio signals are transmitted wirelessly from the mobile phone microphone and headset microphones to the processing unit, eliminating the need for physical cable infrastructure.
4Productivity
If incidental microphones are activated for joint processing, then resource utilization is improved, but system complexity increases
Solution Approach 1:
The patent activates incidental microphones for joint processing only when needed, rather than continuously. The system processes audio signals from multiple microphones selectively based on the recording mode and environmental conditions, avoiding the complexity of continuously managing all possible microphone combinations while still achieving improved resource utilization when beneficial.
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
Improves the signal-to-noise ratio by processing audio signals from multiple microphones, including those not traditionally active, effectively reducing noise in various environments without the encumbrance of extra hardware.
Implementation Method 1
The short-range wireless link may be an optical or infra-red link; a radio link using for example a Bluetooth®
Implementation Method 2
acoustic transducers. The prior art noise canceling microphone operates by pressure difference
Data Source
AI summary
An acoustic noise canceling microphone arrangement and processor that uses a principal microphone and other microphones that may be incidentally or deliberately located in the vicinity of the principal microphone in order to derive an audio signal of enhanced signal-to-background noise ratio. In one implementation, the principal and incidental microphones comprise the microphone built into a mobile phone and the microphone built into a Bluetooth headset.