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Objectively measured and subjectively perceived distortion in nonlinear systems.
1Technical and Experimental Audiology, Karolinska Institutet, Danderyd, Sweden. Ake.Olofsson@ki.se
The Journal of the Acoustical Society of America
|January 18, 2007
Summary
A novel method uses Hilbert pairs to objectively measure nonlinear distortion in transmission systems, including hearing aids. This approach correlates well with subjective distortion perception and traditional metrics.
Area of Science:
- Signal processing
- Acoustics
- Biomedical engineering
Background:
- Nonlinear distortion is a significant challenge in audio transmission systems, affecting signal fidelity.
- Existing methods for measuring distortion may lack versatility or require specific test signals.
- Objective and subjective assessments of distortion often show discrepancies.
Purpose of the Study:
- To introduce a new, versatile objective method for measuring nonlinear distortion.
- To validate the proposed method using hearing aid compression systems.
- To compare objective measurements with subjective distortion perception.
Main Methods:
- The method utilizes the property that Hilbert pairs (real and imaginary parts of an analytical signal) lose their pairing after passing through a nonlinear system.
- The technique was applied to 12 different hearing aid compression systems.
- Objective distortion measurements were compared against subjective assessments from 10 subjects with normal hearing.
Main Results:
- The proposed Hilbert pair-based method demonstrated applicability across various transmission systems and input signals.
- A consistent monotonic relationship was observed between the objective distortion measure and subjective perception.
- The objective measure showed correlation with traditional metrics like total harmonic distortion and signal-to-noise ratio.
Conclusions:
- The Hilbert pair-based method offers a robust and versatile approach for quantifying nonlinear distortion.
- This objective measure aligns well with human perception of distortion in audio systems.
- The method provides a valuable tool for the development and evaluation of audio transmission technologies, particularly hearing aids.
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