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Unformatted text preview: GEORGIA INSTITUTE OF TECHNOLOGY SCHOOL of ELECTRICAL and COMPUTER ENGINEERING ECE 2025 Spring 2009 Lab #9: Cochlear Implant Simulation with a Filter Bank Date: 10–23 Mar. 2009 You should read the Pre-Lab section of the lab and do all the exercises in the Pre-Lab section before your assigned lab time. The Warm-up section of each lab must be completed during your assigned Lab time and the steps marked Instructor Verification must also be signed off during the lab time by one of the laboratory instructors. After completing the warm-up section, turn in the verification sheet to your TA. It is only necessary to turn in Section 4 as the lab report for this lab. More information on the lab report for- mat can be found on t-square under the INFO link. Please label the axes of your plots and include a title and Figure number for every plot. In order to reduce orphan plots , include each plot as a figure embedded within your report. This can be done easily with MATLAB’s notebook capability. For more information on how to include figures and plots from MATLAB in your report file, consult the INFO link on t-square , or ask your TA for details. Forgeries and plagiarism are a violation of the honor code and will be referred to the Dean of Students for disciplinary action. You are allowed to discuss lab exercises with other students and you are allowed to consult old lab reports, but you cannot give or receive written material or electronic files. Your submitted work should be original and it should be your own work. A formal lab report will be due after Spring Break , starting on Wednesday, 1-April. 1 Introduction A cochlear implant serves to overcome deafness by directly stimulating auditory nerve fibers with electrical current thereby conveying auditory cues. The goal of this lab is to mimic the speech processing function of a cochlear implant. To better understand how a cochlear implant functions, it is useful to review the process of hearing. The ear is divided into three parts: outer, middle and inner as shown in Fig. 1(a). During the process of normal hearing, the outer ear captures sound, which the middle ear converts into mechanical vibrations. These vibrations travel into the cochlea, a coiled fluid-filled tube, located in the inner ear. Dividing the fluid- filled tube is a membrane, the basilar membrane that exhibits a variable mechanical stiffness. As a result, it is more sensitive to high frequencies at the base, and more sensitive to low frequencies near the apex (see Fig. 1(b)). The fluid displacement reveals the frequency information of the acoustic signal. Attached to the membrane are small hair cells lined with stereocilia that bend when the membrane is displaced. When bent, these hair cells activate neurons that fire signals to the brain relaying acoustic information. Deafness is caused by the disruption of this hearing process. In the majority of the cases, it is the hair cells that are damaged, not the auditory nerves. A cochlear implant functions by directly stimulating the auditory nervesdamaged, not the auditory nerves....
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This note was uploaded on 10/20/2009 for the course COE 1 taught by Professor Many during the Spring '09 term at Georgia Institute of Technology.

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