Hearing Aid Sampling Rate Converter Synchronization
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Solution Overview
Problem
In hearing aid systems, synchronization issues arise due to lost data packets and variations in clock speed or clock jitter, leading to mismatched sampling delays between left and right hearing aids, causing audio to appear as panning between ears, and existing solutions either introduce artifacts or require device communication for synchronization.
Innovation Solution
A rate matching algorithm and synchronization scheme that adjusts the sampling rate converter to maintain a consistent difference between read and write pointers in the converter output buffer, allowing independent hearing aids to synchronize without device-to-device communication, by using a PID control algorithm to adjust the sampling rate and clock rate based on the RWDiff signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If data packets are streamed separately to left and right hearing aids with alternating timing, then data transmission efficiency is improved, but synchronization between hearing aids deteriorates due to timing delays and lost packets
Solution Approach 1:
The patent applies preliminary action by introducing a predetermined delay to the first data stream before processing. This delay is calculated based on the timing difference between the two hearing aids, ensuring that both streams are synchronized before being processed further. By pre-adjusting the timing offset, the system prevents synchronization issues from propagating through the audio processing pipeline.
Solution Approach 2:
The patent implements feedback mechanisms where each hearing aid monitors its own packet reception timing and communicates synchronization status back to the data source. This feedback loop allows the system to dynamically adjust transmission timing or apply compensatory delays to maintain synchronization, resolving the contradiction between efficient alternating transmission and reliable sync.
2Adaptability or versatility
If sampling rate conversion is performed to match digital signal processor rates, then compatibility is improved, but synchronization accuracy deteriorates due to clock variations and jitter
Solution Approach 1:
The patent applies dynamics by implementing a dynamic sampling rate conversion system that continuously adapts to clock variations. Instead of using a fixed conversion ratio, the system monitors actual packet arrival timing and adjusts the sampling rate conversion factor in real-time. This dynamic adjustment compensates for clock jitter and variations, maintaining synchronization accuracy while preserving compatibility with different digital signal processor rates.
3Reliability
If initialization delay is introduced to align first packets between hearing aids, then initial synchronization is improved, but overall processing speed deteriorates
Solution Approach 1:
The patent applies preliminary action by calculating and applying the necessary delay during the initialization phase only. Once synchronization is established, the system transitions to a mode where no additional delay is applied to subsequent packets. This approach ensures proper initial alignment without permanently slowing down the processing of ongoing audio streams.
Solution Approach 2:
The patent implements periodic synchronization checks where the system monitors packet timing continuously and applies delay corrections only when desynchronization is detected. This periodic approach maintains synchronization reliability while minimizing the impact on processing speed, as delays are applied intermittently rather than continuously.
Data Source
AI summary
Methods of compensating for lost data packets in hearing aid systems wherein a data streaming device streams packets of data to at least two hearing aids are disclosed.