Filter Bank Latency Reduction via Signal Prediction
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Solution Overview
Problem
Hearing aids experience significant latency due to the transformation of audio signals from the time domain to the frequency domain, leading to comb-filter effects and distorted sound, particularly in binaural systems, where the internal processing latency and filtering contribute to temporal offsets and increased susceptibility to these effects.
Innovation Solution
A method is introduced to reduce latency by forming signal blocks from audio signals, estimating signal components for a prediction period, and transforming the predicted signal blocks with a predetermined filter function into the frequency domain, allowing for immediate processing and output without the need for all samples to be present, thereby minimizing latency and maintaining high frequency resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the audio signal is transformed from time domain to frequency domain with high resolution, then frequency resolution is improved, but latency is increased
Solution Approach 1:
The patent applies preliminary action by estimating signal components for a prediction period before the actual signal data is available. This allows the filtering process to start earlier using predicted values, thereby reducing latency while maintaining frequency resolution. The estimation is performed for at least a partial interval of the signal block, enabling the system to proceed with processing without waiting for all samples to be present.
2Adaptability or versatility
If signal blocks are transformed into frequency domain for filtering, then frequency-selective processing is improved, but comb-filter effects are increased due to latency
Solution Approach 1:
By estimating signal components in advance for the prediction period, the system reduces the temporal offset between direct sound and output acoustic signal. This minimizes the conditions that lead to comb-filter effects while preserving the ability to perform frequency-selective processing on the transformed signal blocks.
3Measurement precision
If all samples of a signal block are required before transformation, then processing accuracy is improved, but latency is increased
Solution Approach 1:
The patent applies partial action by performing the transformation and filtering operations on a predicted signal block before all actual samples are available. The estimation provides sufficient accuracy for the prediction period, allowing processing to proceed with partial information rather than waiting for complete signal blocks, thus reducing latency while maintaining acceptable processing accuracy.
Data Source
AI summary
A method for reducing the latency period of a filter bank for filtering an audio signal. A large number of signal blocks in the time domain are formed from the audio signal, wherein for at least a plurality of the signal blocks in each instance a filter function is predetermined, at least one partial interval of the signal block is predetermined as a prediction period, signal components of the signal block in the at least one partial interval are estimated for the prediction period, and a predicted signal block is generated from the signal components estimated for the prediction period and from the signal components of the signal block outside the prediction period. The predicted signal block, filtered with the predetermined filter function, is transformed into the frequency domain to form a transformed signal block. Signal components of the transformed signal block are output for further processing.