My Work


I came to the Univeristy of Illinois in 1997 to pursue a Masters degree in electrical engineering.  I was a teaching assistant in an introductory electrical engineering lab course for two semesters, and then I received a research assistantship to work with the Intelligent Hearing Aid group.  My thesis was entitled "Development and testing of a frequency-domain minimum-variance algorithm for use in a binaural hearing aid," and I received my degree in 1999.  I began working as a full-time research engineer with this group in 2000.

Over the past four years I've done acoustic signal processing at the Beckman Institute at the University of Illinois.  My work was first funded through a research agreement with Phonak, AG, a Swiss hearing aid company.  Next, I worked on a DARPA grant that sought to develop MEMS (micro-electrical mechanical systems) microphones and novel signal processing algorithms to perform beamforming and spatial localization with the novel sensors.  The goal was to develop small sensors that could be dropped on a battlefield and could then determine the locations of troops, vehicles, aircraft, etc.

Continuity with our previous work is mainteined through our latest grant, from NIH, which involves creating MEMS sensors and signal processing algorithms to be used in future hearing aids.  This work is scheduled to be completed in about three more years.

My goals are to continue to do fruitful research in the areas of acoustic beamforming and source localization, specifically algorithm development, real-time system design and implementation, and high-fidelity recordings for algorithm testing.  Additionally, I am interested in the problems associated with nonstationary sources, particularly speech, and algorithms that can tolerate and even take advantage of the nonstationarity while canceling other (possibly nonstationary) interference.  The most common example of this is extracting a single speech source in an environment with many other spatially distributed speech sources, also known as the "cocktail party problem."  Yet another problem related to these is the issue of room reverberation.

Publications, etc.

Feng, A.S., Lockwood, M.E., Jones, D.L., Bilger, R.C., Lansing, C.R., O'Brien, W.D., Wheeler, B.C., "Systems and methods for interference-suppression with directional sensing patterns", US Patent 7,076,072 B2, July 11, 2006.

Lockwood, M. E., Jones, D. L., (2006) "Beamformer performance with acoustic vector sensors in air," J. Acoust. Soc. Am, 119, 608-619.

Lockwood, M. E., Jones, D. L., Bilger, R. C., Lansing, C. R., O'Brien., W. D. Jr., Wheeler, B. C., and Feng, A. S. (2004) “Performance of time- and frequency-domain binaural beamformers based on recorded signals from real rooms,” J. Acoust. Soc. Am, 115, 379-391.

Lockwood, M. E., Jones, D. L., Su, Q., and Miles, R. N. (2003) "Beamforming with collocated microphone arrays," J. Acoust Soc. Am., 114, 2451.

Lockwood, M.E., Jones, D.L., Elledge, M.E., Bilger, R.C., Feng, A.S., Goueygou, M., Lansing, C.R., Liu, C. O'Brien, W.D. Jr., Wheeler, B.C. (1999) "A minimum variance frequency-domain algorithm for binaural hearing aid processing.," J. Acous. Soc. Am., 106 (Pt. 2): 2278A.

Lockwood, M.E., Yang, K.L., Jones, D.L., Bilger, R.C., Lansing, C.R., Liu, C., O’Brien, W.D., Wheeler, B.C. and Feng, A.S. (2001) "Robustness of the beamforming algorithms with head-related transfer functions," J. Acoust. Soc. Am. 109, 2493.

Lockwood, M.E., Elledge, M.E., Yang, K.L., Jones, D.L., Lansing, C.R., Bilger, R.C., Wheeler, B.C., O’Brien, W.D. and Feng, A.S. (2000) "Simulation and real-time implementation of a new optimum beamforming technique", Intern. Hearing Aid Research Conference in Lake Tahoe (CA): 32-33.

Elledge, M.E., Lockwood, M.E., Bilger, R.C., Feng, A.S., Goueygou, Jones, D.L., M., Lansing, C.R., Liu, C. O'Brien, W.D. Jr., Wheeler, B.C. (1999) "A real-time dual-microphone signal-processing system for hearing aids," J. Acous. Soc. Am. 106 (Pt. 2): 2279A.

Elledge, M.E., Lockwood, M.E., Bilger, R.C., Feng, A.S., Jones, D.L., Lansing, C.R. O’Brien, W.D. and Wheeler, B.C. (2000) "Real-time implementation of a frequency-domain beamformer on the TI C62X EVM," Presented in 10th Ann. DSP Technol. Educ. and Res. Conf. held in Houston (TX), August 2-4, 2000.

Mohan, S., Lockwood, M. E., Jones, D. L., Su, Q., and Miles, R. N. (2003) "Sound source localization with a gradient array using a coherence test," J. Acoust Soc. Am., 114, 2451.

Zheng, Y., Lockwood, M.E., Wheeler, B.C., Jones, D.L., Feng, A.S., O’Brien, W.D., Bilger, R.C., Lansing, C.R. (2001) "Comparison of binaural beamformers for speech extraction in complex auditory scenes," J. Acoust. Soc. Am. 109, 2494.

Berry, M. Lockwood, M.E., Jones, D.L., Bilger, R.C., Lansing, C.R., Liu, C., O’Brien, W.D., Wheeler, B.C. and Feng, A.S. (2001) "Beamformer improvement with increasing number of sensors," J. Acoust. Soc. Am. 109, 2494.

Yang, K.L., Lockwood, M.E.,  Elledge, M.E. and Jones, D.L. (2000) "A comparison of beamforming algorithms for binaural acoustic processing," Proc. 9th IEEE Digital Signal Processing Workshop. Hunt (TX), October 15-18, 2000.

Larsen, J., Lockwood, M.E., Lansing, C.R., Bilger, R.C., O’Brien, W.D., Jones, D.L., Wheeler, B.C. and Feng, A.s. (2001) "Performance of a frequency-based minimum variance beamforming algorithm for normal and hearing impaired listeners," Abstr. 24th Annual Midwinter Meeting of the Assoc. Res. Otolaryngol., p. 174.

Larsen, J., Lockwood, M.E., Lansing, C.R., Bilger, R.C., O’Brien, W.D., Jones, D.L., Wheeler, B.C. and Feng, A.S. (2001) "Performance of a frequency-based minimum variance beamforming algorithm for normal and hearing impaired listeners," J. Acoust. Soc. Am. 109, 2494.

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