Voice-Band Compression Timing for Clearer Hearing-Impaired Speech
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Solution Overview
Problem
Existing audio processing techniques for hearing-impaired individuals face challenges in providing sounds that are easy to hear, as dynamic range compression can lead to unnatural fluctuations in sound volumes and fail to adequately emphasize the beginnings of words, which are crucial for clarity.
Innovation Solution
An audio processing apparatus that includes a microphone, preprocessor, controller, and multiplier, which generates and smoothes amplification coefficients to control the dynamic range compression, emphasizing the beginnings of words by setting the rise time constant greater than or equal to the temporal resolution of hearing-impaired individuals and less than the duration time that induces recruitment, thereby preventing rapid suppression of sound intensities and amplifying the output signal immediately after the rise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the attack time constant is reduced to quickly decay large intensity signals and avoid recruitment, then recruitment is avoided, but the beginnings of words are rapidly suppressed making them hard to hear
Solution Approach 1:
The patent segments the dynamic range compression process into two distinct time constant parameters: attack time constant for decaying large intensity signals and release time constant for amplifying low intensity signals. By separating these functions and optimizing each independently, the system avoids rapid suppression of word beginnings while preventing recruitment
Solution Approach 2:
The patent changes the parameter values of time constants based on signal intensity characteristics. The attack time constant is set to a specific range (10-100ms) that is sufficiently long to preserve word beginnings but short enough to prevent recruitment, while the release time constant is set longer (50-500ms) to avoid unnatural fluctuations
2Stability of the object's composition
If the release time constant is increased to suppress unnatural fluctuations, then sound volume stability is improved, but the response to low intensity signals is delayed
Solution Approach 1:
The patent implements dynamic time constant selection where the attack and release time constants are differentiated based on the signal intensity state. The system dynamically adjusts compression behavior by using shorter attack time for high intensity signals and longer release time for low intensity signals, optimizing both stability and response speed
Data Source
AI summary
An audio processing apparatus includes a preprocessor which extracts a voice-band signal from a first electric signal, and outputs a first output signal containing the voice-band signal; a first controller which generates a first amplification coefficient for multiplying with the first output signal to compress a dynamic range of an intensity of the first output signal, and generates a first modified amplification coefficient by smoothing the first amplification coefficient with a first time constant; and a first multiplier which multiplies the first modified amplification coefficient and the first output signal. The first time constant is a first rise time constant when the intensity increases, and is a first decay time constant when the intensity decreases. The first rise time constant is not less than a temporal resolution of hearing of a hearing-impaired person, and is less than a duration time of sound which induces recruitment in the hearing-impaired person.