Modulation Depth Enhancement for Auditory Prostheses
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Solution Overview
Problem
Current speech processing strategies for auditory prostheses, such as cochlear implants and hearing aids, do not adequately code voice pitch information, particularly in cases where the modulation depth of sound signals is shallow, leading to suboptimal perception of voice pitch and musical tone.
Innovation Solution
A sound processing strategy that selectively increases the modulation depth of envelope signals in defined frequency channels when it falls below a predetermined threshold, using a Modulation Depth Enhancement (MDE) algorithm to expand modulation depths, thereby improving the identification of modulation frequency and pitch perception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If channelization of sound signal is used for speech coding, then speech processing efficiency is improved, but modulation depth in individual channels becomes insufficient (less than 6 dB)
Solution Approach 1:
The patent divides the sound signal into multiple frequency channels using channelization, which improves processing efficiency. However, this segmentation causes the modulation depth to be distributed and reduced in each individual channel. The invention accepts this trade-off by subsequently enhancing the modulation depth through envelope modulation to compensate for the loss.
Solution Approach 2:
The patent changes the modulation parameter by applying envelope modulation to increase the modulation depth in channels where it falls below the threshold. This parameter change compensates for the modulation depth loss caused by channelization while maintaining the benefits of efficient speech processing.
2Loss of information
If envelope modulation is used to code voice pitch information, then pitch coding is achieved, but modulation depth remains insufficient for reliable detection
Solution Approach 1:
The patent implements a feedback mechanism where the modulation depth of each channel is monitored and compared against a threshold value. When the modulation depth falls below the threshold, envelope modulation is applied to enhance it. This feedback loop ensures that pitch information is reliably coded while maintaining sufficient modulation depth for detection.
Solution Approach 2:
The patent dynamically adjusts the modulation depth parameter through envelope modulation when it falls below the reliable detection threshold. This parameter change ensures that pitch information is both coded and detectable with sufficient reliability.
3Measurement precision
If modulation depth enhancement is applied to all channels, then pitch perception is improved, but processing complexity increases
Solution Approach 1:
The patent applies modulation depth enhancement selectively only to channels where the modulation depth falls below a predetermined threshold, rather than uniformly to all channels. This local quality approach improves pitch perception accuracy where needed while minimizing unnecessary processing complexity in channels that already have sufficient modulation depth.
Data Source
AI summary
A sound processing process is disclosed, 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.