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.