Auditory Prosthesis Pitch Perception via Envelope Phase Alignment
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Solution Overview
Problem
Current auditory prostheses, such as cochlear implants, face challenges in effectively processing sound signals to convey pitch information, particularly in tonal languages and music, due to inadequate coding of modulation frequency in channel envelope signals, leading to compromised voice and musical pitch perception.
Innovation Solution
The method involves processing sound signals to produce channel signals in spaced frequency channels, determining envelope signals, and modulating them with a broadband envelope signal to synchronize phases, while also enhancing modulation depth to improve the identification of modulation frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional channelization strategies are used to process sound signals, then the device complexity is reduced and ease of operation is improved, but pitch perception accuracy deteriorates due to inadequate coding of modulation frequency
Solution Approach 1:
The sound signal is divided into multiple frequency channels using a filter bank, with each channel processed independently to extract envelope signals. This segmentation allows pitch information to be coded across multiple channels while maintaining manageable complexity in each individual channel processing path.
Solution Approach 2:
Pitch information is encoded not only through temporal modulation frequency but also through the spatial distribution of envelope signals across multiple frequency channels. By adding the dimensional aspect of channel distribution, the system achieves more robust pitch perception without proportionally increasing processing complexity.
2Measurement precision
If envelope signals are modulated with broadband envelope signals to synchronize phases, then pitch perception is improved, but the device complexity increases due to additional processing requirements
Solution Approach 1:
Envelope signals from multiple frequency channels are combined and modulated by a common broadband envelope signal to synchronize their phases. This merging approach ensures that pitch information is consistently represented across all channels, improving modulation frequency identification while sharing the modulation processing load across the channel group.
Solution Approach 2:
The broadband envelope signal serves multiple functions: it provides phase synchronization across channels, carries modulation frequency information, and enhances pitch perception. This multi-functionality reduces the need for separate processing mechanisms, thereby limiting the increase in overall system complexity.
3Reliability
If modulation depth is enhanced to improve pitch perception, then the reliability of pitch information transmission is improved, but energy consumption increases
Solution Approach 1:
Modulation depth enhancement is applied selectively to specific frequency channels based on their contribution to pitch information, rather than uniformly across all channels. This localized approach ensures reliable pitch transmission in critical channels while reducing unnecessary energy consumption in channels where enhancement is less important.
Solution Approach 2:
The modulation depth parameter is dynamically adjusted based on the detected modulation frequency and channel characteristics. By changing this parameter adaptively rather than maintaining a fixed high value, the system achieves reliable pitch information transmission while optimizing energy consumption according to actual processing needs.
Data Source
AI summary
A sound processing process, device and software are disclosed which seek to improve pitch perception, with particular application to auditory prostheses. After input sound signals are processed into channels, an algorithm is applied to selectively increase the modulation depth of the envelope signals. In certain embodiments, the channelized signals are adjusted in timing so as to align the phase of modulated envelope signals in different channels. This results in provision of synchronous (phase aligned) modulation periodicity across channels and hence less pitch ambiguity for listeners to the processed signal, or for application of the signal to hearing prostheses such as cochlear implants. In some embodiments, a broadband envelope signal is used to modulate the level of the narrow band channel signals, so that voicing frequency modulation information in the broadband envelope signal is provided in all narrow band channel signals and the phase of modulated signals in the channels are aligned. A preferred form uses an envelope signal which is modified to increase its modulation depth, and is normalized so as to allow for modulation of the channel signals.