The Consonant-Weighted Envelope Difference Index (cEDI): A Proposed Technique for Quantifying Envelope Distortion PurposeThe benefits of amplitude compression in hearing aids may be limited by distortion resulting from rapid gain adjustment. To evaluate this, it is convenient to quantify distortion by using a metric that is sensitive to the changes in the processed signal that decrease consonant recognition, such as the Envelope Difference ... Research Note
Research Note  |   December 01, 2012
The Consonant-Weighted Envelope Difference Index (cEDI): A Proposed Technique for Quantifying Envelope Distortion
 
Author Affiliations & Notes
  • Pamela E. Souza
    Northwestern University, Evanston, IL
  • Frederick J. Gallun
    National Center for Rehabilitative Auditory Research, Department of Veterans Affairs, Portland, OR
  • Correspondence to Eric C. Hoover: EricHoover2014@u.northwestern.edu
  • Editor: Sheila Pratt
    Editor: Sheila Pratt×
  • Associate Editor: Catherine Palmer
    Associate Editor: Catherine Palmer×
Article Information
Speech, Voice & Prosody / Hearing
Research Note   |   December 01, 2012
The Consonant-Weighted Envelope Difference Index (cEDI): A Proposed Technique for Quantifying Envelope Distortion
Journal of Speech, Language, and Hearing Research, December 2012, Vol. 55, 1802-1806. doi:10.1044/1092-4388(2012/11-0255)
History: Received September 16, 2011 , Accepted March 5, 2012
 
Journal of Speech, Language, and Hearing Research, December 2012, Vol. 55, 1802-1806. doi:10.1044/1092-4388(2012/11-0255)
History: Received September 16, 2011; Accepted March 5, 2012
Web of Science® Times Cited: 1

PurposeThe benefits of amplitude compression in hearing aids may be limited by distortion resulting from rapid gain adjustment. To evaluate this, it is convenient to quantify distortion by using a metric that is sensitive to the changes in the processed signal that decrease consonant recognition, such as the Envelope Difference Index (EDI; Fortune, Woodruff, & Preves, 1994). However, the EDI relies on the entire duration of the signal, including portions irrelevant to consonant recognition.

MethodThis note describes a computationally efficient method of automatically segmenting speech in time according to the syllable structure. Our technique uses the 1st derivative of the envelope as a basis. Peaks located in the derivative were used to generate a weighting function for the computation of a metric of signal distortion.

ResultsThe weighting function significantly improved the variance explained in consonant recognition scores over previous methods. However, only 3.2% of the variance was explained in the revised model.

ConclusionThis technique was effective in focusing the analysis of distortion on specific segments of the signal. Use of the technique has implications for speech analysis. The difference in the amplitude envelope of consonants is not a robust model of the effect of hearing aid compression on consonant recognition.

Acknowledgments
This work was supported by National Institutes of Health Grant DC0060014 and by Veterans Health Administration Rehabilitation Research and Development Service Grant C4963W.
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