Instrument identification through a simulated cochlear implant processing system
I am very interested in the cochlear implant, a neural prosthesis for the profoundly hearing-impaired. The primary design goal of these devices is to restore hearing sufficient to communicate fluently without lip-reading. In other words, the device can deliver speech and environmental signals to a relatively high degree of accuracy. However, the processing distorts musical signals, due to the different structure of the signal. It is my goal to understand what kind of information, relevant to identifying musical instruments, is rejected by the implant in an effort to suggest possible improvements to the design.
My thesis proposal can be found here (a .zip archive of an MSWord file).
I will be conducting some subjective experiments as part of my thesis. I simulate part of the implant's processing using MATLAB and run audio signals, consisting of solo synthetic instrument recordings, through the simulation. The intention is NOT to represent what an implant recipient is hearing; rather, it is an investigation of only a small part of the processing. Normal-hearing listeners will then identify musical instruments from the processed signals. I anticipate the scores to be rather low, and it will be interesting to learn what perceptual features are being used in the identification process.
Here is a link to my poster (a powerpoint file) for the Media Lab poster session, March 2002. It is better to download the file and view it in powerpoint as it is a large size.
I am presenting a poster at the Meeting of the Acoustical Society of America with preliminary results of my experiments with 15 subjects. Click here for a PDF version of the poster.
This just in! My thesis is done. Click here (about 5MB) for the PDF version. The font isn't as nice as it was when I handed it in...
Sound Samples
REAL INSTRUMENTS
Bassoon Unprocessed Processed (Full-Wave) Processed (Half-Wave)
Piano Unprocessed Processed (Full-Wave) Processed (Half-Wave)
Violin Unprocessed Processed (Full-Wave) Processed (Half-Wave)
SYNTHESIZED INSTRUMENTS
Bassoon Unprocessed Processed (Full-Wave) Processed (Half-Wave)
Piano Unprocessed Processed (Full-Wave) Processed (Half-Wave)
Violin Unprocessed Processed (Full-Wave) Processed (Half-Wave)