Hearing Aid Rate Matching via RWDiff PID Control
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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 pan between ears and resulting in unsynchronized audio processing.
Innovation Solution
A rate matching algorithm and synchronization scheme that adjusts the sampling rate converter to maintain a consistent difference between the read and write pointers in the converter output buffer, ensuring synchronized data processing 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 separate data streams are sent to left and right hearing aids, then data can be transmitted to both devices, but synchronization is lost due to timing delays and lost packets
Solution Approach 1:
The patent applies preliminary action by introducing synchronization packets before the actual audio data packets. These synchronization packets contain timing information that allows each hearing aid to adjust its internal clock and buffer alignment in advance, ensuring that audio data from both ears is processed at the correct time despite transmission delays or packet loss. This preliminary timing setup prevents desynchronization without requiring complex real-time coordination between devices.
2Adaptability or versatility
If rate matching is performed independently in each hearing aid, then each device can adapt to its own sampling rate, but audio panning occurs due to mismatched processing timing
Solution Approach 1:
The patent implements feedback by using synchronization packets to provide timing information back to the audio processing system in each hearing aid. This feedback loop allows the system to continuously monitor and adjust the buffer alignment and processing timing based on actual packet arrival times and synchronization signals, ensuring that audio data is processed at consistent time intervals across both ears while maintaining independent sampling rate adaptation.
3Device complexity
If no device-to-device communication is used, then device complexity is reduced, but synchronization must be achieved through other means
Solution Approach 1:
The patent introduces synchronization packets as an intermediary element that carries timing information without requiring direct device-to-device communication. These packets act as mediators between the data source and the hearing aids, providing the necessary synchronization information embedded within the audio data stream itself. This approach maintains synchronization reliability while avoiding the complexity of establishing separate communication channels between devices.
Data Source
AI summary
Hearing aid systems where a data streaming device streams data to a hearing aid and methods of maintaining synchronization when converting a sampling rate are disclosed. A hearing system comprises a hearing aid, a sampling rate converter, a buffer, an RDWiff signal, and a control circuit. The hearing aid receives data from a data transmission device, and the data received has a first sampling rate. The sampling rate converter is in the hearing aid and converts the sampling rate of the received data to a sampling rate suitable for use by digital signal processing circuitry in the hearing aid. The buffer receives data from the sampling rate converter. The RWDiff signal indicates the difference between the rate at which data is read from and written to the buffer. The control circuit compares the RWDiff signal to a predetermined RWIdeal quantity and generates an adjustment signal.