Hearing Aid Compression System for Natural Sound Envelope Preservation
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Solution Overview
Problem
Hearing assistance devices face challenges in accurately amplifying and processing sounds of different frequencies and levels, leading to improper gain application and artificial envelope fluctuations when multiple sounds are present, particularly in complex audio mixes like music or movie soundtracks, resulting in an unnatural auditory experience.
Innovation Solution
Applying compression to individual sound sources before mixing, using a system that separates and compresses each sound source independently before recombining them, such as in a surround sound synthesizer, to ensure proper gain adjustment and avoid cross-modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If compression is applied to mixed sounds after mixing, then the device complexity is reduced, but the manufacturing precision of gain application deteriorates causing artificial envelope fluctuations
Solution Approach 1:
The patent segments the audio signal processing by separating individual sound sources before compression. Instead of compressing the mixed signal as a whole, the system identifies and processes each sound source (e.g., speech, music, noise) independently with its own compression parameters, then remixes them. This segmentation enables precise gain application to each source while maintaining manageable system complexity through modular processing.
Solution Approach 2:
The patent applies compression preliminarily to individual sound sources before they are mixed together. By pre-compressing each sound source with appropriate gain settings based on its characteristics and the desired output level, the system avoids the need for complex post-mixing compression adjustments, thereby maintaining precision without excessive complexity.
2Ease of operation
If a single gain value is applied to multiple simultaneous sounds, then the ease of operation is improved, but the reliability of sound level perception deteriorates
Solution Approach 1:
The patent implements dynamic gain control that adapts to the characteristics of each sound source. The system continuously monitors the levels and types of sounds present and adjusts compression parameters dynamically for each source. This dynamic approach maintains operational simplicity while ensuring that each sound source receives the appropriate gain to achieve natural perceived loudness.
Solution Approach 2:
The patent changes compression parameters (such as compression ratio, attack time, release time, and threshold) based on the type and level of each sound source. By automatically adjusting these parameters for different sound sources like speech versus music, the system maintains ease of operation without manual intervention while achieving reliable and natural sound level perception.
3Device complexity
If compression is applied after mixing sounds, then the device complexity is reduced, but the loss of information increases due to cross-modulation and envelope fluctuations
Solution Approach 1:
The patent segments the mixed signal into individual sound sources before applying compression. By separating speech from music, speech from noise, and other sound sources, the system preserves the original envelope characteristics of each source during compression, preventing cross-modulation artifacts and information loss that would occur with post-mixing compression.
Solution Approach 2:
The patent introduces sound source separation and identification as an intermediary process between mixing and compression. This intermediary step analyzes the mixed signal to identify individual sources and their characteristics, enabling subsequent compression to be applied in a way that preserves the integrity of each source's temporal envelope while still achieving the desired overall compression effect.
Data Source
AI summary
This application relates to a system for compression and mixing for hearing assistance devices by application of compression to individual sound sources before mixing, according to one example. Variations of the present system using surround sound provide separate signals from a surround sound synthesizer which are compressed prior to mixing of the signals.