Frequency Transposition by Envelope Shifting for Hearing Compensation
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Solution Overview
Problem
Conventional hearing aids face challenges in compensating for hearing impairments, particularly due to feedback oscillation issues and 'dead regions' where amplification is ineffective, leading to poor sound quality and speech intelligibility for hearing-impaired individuals.
Innovation Solution
The method involves transposing the envelope information of higher frequency source bands to lower frequency target bands while maintaining the phase information, allowing for improved sound quality and speech intelligibility by combining the envelope of the source band with the phase of the target band, without discarding any spectral information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional amplification is used to compensate for hearing impairment at certain frequencies, then hearing ability is improved, but feedback oscillation occurs or dead regions cannot be compensated
Solution Approach 1:
The patent uses frequency transposition as an intermediary mechanism to transfer inaudible high-frequency information to audible frequency ranges. Instead of directly amplifying frequencies that cause feedback oscillation or cannot be heard due to dead regions, the system transposes these frequencies to alternative audible ranges, thereby avoiding the harmful effects while preserving the informational content.
Solution Approach 2:
The patent changes the frequency parameter of inaudible sound components by transposing them to different frequency ranges. Specifically, it extracts the envelope of high-frequency source bands and combines it with the phase of lower-frequency target bands, effectively relocating the frequency content from inaudible to audible ranges without direct amplification of the problematic frequencies.
2Reliability
If frequency transposition is applied to improve speech intelligibility, then speech understanding is enhanced, but sound quality may be degraded
Solution Approach 1:
The patent segments the frequency spectrum into source bands (high-frequency, inaudible) and target bands (lower-frequency, audible). By processing these segments separately and selectively combining envelope information from source bands with phase information from target bands, the system preserves the natural temporal structure and quality characteristics of audible frequencies while adding information from inaudible frequencies.
Solution Approach 2:
The patent applies different processing strategies to different frequency regions. High-frequency source bands undergo envelope extraction, while lower-frequency target bands provide phase information that is preserved. This local differentiation ensures that each frequency region contributes its most valuable characteristics to the final output, maintaining overall sound quality while improving speech intelligibility.
3Reliability
If high amplification is applied to compensate for dead regions, then hearing sensitivity is improved, but the location of the basilar membrane cannot be effectively stimulated
Solution Approach 1:
The patent uses frequency transposition as an intermediary to bypass dead regions on the basilar membrane. By transposing inaudible high-frequency information to audible lower frequencies, the system delivers auditory information through functional regions of the basilar membrane rather than attempting to stimulate non-functional dead regions directly, thereby effectively compensating for hearing loss at those locations.
Data Source
AI summary
The application relates to a method of improving a user's perception of an input sound. The application further relates to an audio processing device and to its use. The object of the present application is to increase the sound quality of a sound signal as perceived by a user, e.g. a hearing impaired user. The method comprises a) Defining a critical frequency fcrit between a low frequency range and a high frequency range; b) Analyzing an input sound in a number of frequency bands below and above said critical frequency; c) Defining a cut-off frequency fcut below said critical frequency fcrit; d) Identifying a source frequency band above said cut-off frequency fcut; e) Extracting the envelope of said source band; f) Identifying a corresponding target band below said critical frequency fcrit; g) Extracting the phase of said target band; h) Combining the envelope of said source band with the phase of said target band. This has the advantage of increasing the sound quality, and the potential to further improve speech intelligibility in frequency transposition, e.g. frequency lowering systems. The invention may e.g. be used in communication devices, such as telephones, or listening devices, e.g. hearing instruments, headsets, head phones, active ear protection devices or combinations thereof.