Hearing Assistance Microphone Network Voice Activity Control
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Solution Overview
Problem
Current hearing assistance systems with multiple wireless microphones face limitations in meeting situations due to the need for only one microphone to transmit at a time, leading to potential sentence clipping and increased noise and reverberation when multiple speakers overlap.
Innovation Solution
A system utilizing at least two table microphone units with omnidirectional characteristics, each equipped with an energy-based voice activity detector and a control unit, where only one microphone is active at a time based on voice activity detection, employing a 'first come' principle with override criteria and adjustable release times to minimize unwanted switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If only one microphone transmits at a time in a multi-talker network, then network bandwidth is conserved and system complexity is reduced, but speech quality deteriorates due to sentence clipping when multiple speakers overlap
Solution Approach 1:
The patent segments the audio signal processing by separating voice activity detection (VAD) from speech enhancement functions. Multiple microphones perform VAD independently and locally, determining voice activity without centralized coordination. This segmentation allows parallel operation of multiple microphones during overlapping speech, improving speech quality while maintaining manageable system complexity through distributed decision-making.
2Speed
If voice activity detection is made very fast to capture speech start, then speech capture improves, but false detections increase causing unwanted microphone switching and reduced robustness
Solution Approach 1:
The patent applies preliminary action by performing voice activity detection at multiple microphones simultaneously before any switching decision is made. Each microphone independently detects voice activity in advance, and the system prepares to switch to the active microphone proactively rather than reactively. This preliminary detection at all microphones prevents false switching by having all options ready before speech begins.
Solution Approach 2:
The system implements feedback mechanisms where microphones continuously monitor voice activity and provide status information to the network. This feedback loop allows the system to adjust microphone selection dynamically based on actual speech presence, reducing false detections by confirming voice activity across multiple detection points before triggering a switch.
3Adaptability or versatility
If multiple omnidirectional microphones transmit simultaneously, then coverage is improved, but noise and reverberation increase due to signal mixing
Solution Approach 1:
The patent applies dynamics by making the microphone transmission state dynamic rather than static. Microphones transition between active and inactive states based on real-time voice activity detection. This dynamic switching allows the system to adapt to changing speech patterns, providing omnidirectional coverage when needed while minimizing noise and reverberation by activating only one microphone at a time when speech is present.
Data Source
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AI summary
There is provided a multi-talker acoustic network system for providing hearing assistance to a user, comprising at least two table microphone units (10, 12) for capturing audio signals from a speaker's voice, each comprising a microphone arrangement (30) having an omnidirectional characteristic, a VAD (32) for detecting voice activity of the microphone arrangement and a transmitter (36) for transmitting the captured audio signals via a wireless audio link (40), a control unit (34) for selecting one of the table microphone units as the presently active microphone unit, wherein the control unit is configured to select, in case that at a time only for one of the table microphone units voice activity is detected, that one of the table microphone units as the presently active microphone unit, and to select, in case that at a time for more than one of the table microphone units voice activity is detected, at least for a certain time period that one of the table microphone units as the presently active microphone unit which has detected the voice activity first as the presently active microphone unit, wherein the system is configured to maintain the selection of the presently active microphone unit with a release time, and a hearing assistance device (20, 22) to be worn by the user, comprising a receiver unit (42) for receiving audio signals captured by the presently active microphone unit and an output transducer (44) for stimulation of the user's hearing according to the received audio signals, wherein the system is configured to prevent audio signals of the table microphone unit(s) not being the presently active microphone unit from being supplied to the output transducer.