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Meeting Number:   2

December 5, 2005


Time-Varying Compression Amplification That Preserves Spectral Shape


Janet C. Rutledge, Ph.D.
Senior Associate Dean of the Graduate School
University of Maryland, Baltimore County


Monday, December 5, 2005


5:45 PM:   Food
6:00 PM:   Presentation


Historical Electronics Museum (HEM)
1745 W. Nursery Road, Linthicum, MD 21090

Please Respond To


Multichannel amplitude compression processing is used to reduce the level variations of speech to fit the reduced dynamic ranges of listeners with sensorineural hearing loss. This processing, however, can result in smearing of temporal information, artifacts due to spectral discontinuities at fixed channel edges, and spectral flattening due to reduced peak-to-valley ratios. Presented here is an implementation of a time-varying compression processing algorithm based on a sinusoidal speech model (Col-SM). The algorithm operates on a time-varying, stimulus-dependent basis to adjust to the speech variations and the listener’s hearing profile. The algorithm provides fast-acting compression without artifact, has time-varying frequency channels, is computationally inexpensive and preserves the important spectral peaks in speech. Frequency resolution is particularly important for segregating speech from noise, and one person’s speech from another’s, especially in older listeners. Preliminary subject tests indicate benefit from real-time Col-SM processing that is greater than that from fixed-frequency multichannel compression without some of the undesirable artifacts. This method could be extended to provide real-time enhancement of spectral contrast.


Dr. Janet C. Rutledge is the Senior Associate Dean of the Graduate School at the University of Maryland, Baltimore County (UMBC). She has faculty appointments in the Computer Science and Electrical Engineering Department at UMBC and in the School of Medicine at the University of Maryland, Baltimore. Before coming to UMBC she served as the Program Director for the Graduate Research Fellowship Program at the National Science Foundation. Prior positions at NSF include program director in the Division of Engineering Education and Centers, and in the Division of Undergraduate Education. Formerly she was a faculty member in the Electrical and Computer Engineering Department at Northwestern University. Her primary research area is modeling and compensating for the effects of sensorineural hearing loss and other communication disorders. She is the author of numerous journal and conference publications, an undergraduate textbook, and holds a patent. She has held several leadership positions in the IEEE. She is also a member of the Georgia Tech Engineering Advisory Board, and the Rensselaer Polytechnic Institute Board of Trustees.

Dr. Rutledge has held several professional society leadership positions, including: Institute of Electrical and Electronic Engineers (IEEE) Committee on Engineering Accreditation Activities (2000-2003); Electrical and Biomedical Engineering Program Evaluator for the Accreditation Board of Engineering and Technology (ABET); Speech Technical Committee of the Acoustical Society of America (1994-99); Administrative Committee of the IEEE Engineering in Medicine and Biology Society (1998-2001); Editorial Board of the IEEE Press Series on Emerging Technologies in Biomedical Engineering (1995-2002); Administrative Committee of the IEEE Education Society and electronic associate editor of the IEEE Transactions on Education (1997-99).

Dr. Rutledge received the B.S. degree in electrical engineering from Rensselaer Polytechnic Institute in 1983. She received the M.S. and Ph.D. in electrical engineering from the Georgia Institute of Technology in 1984 and 1990, respectively.

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