碩士 / 國立臺灣大學 / 醫學工程學研究所 / 93 / Tinnitus is prevalent among 10% of the general population and tends to increase in frequency among older ages. It has been difficult for the physicians to make a clinical evaluation of this annoying symptom since there lacks an objective approach to the diagnosis. To investigate the brain processes underlying tinnitus as well as to evaluate the symptoms objectively, multi-channel EEG recording is applied to investigate the appearance of ERPs (Event-Related Potentials) in tinnitus patients. ERPs were recorded from sixteen tinnitus patients and fifteen normal controls. All subjects have no significant hearing loss. A tone burst of 0.5, 1, 2, and 4 kHz are used as auditory stimuli. The stimuli of each frequency are presented at five different intensities: 50, 56, 62, 68, and 74 dB SBL. The intensity dependences of the N100/P200 amplitude and N100 latency are calculated for each frequency in each group. Aside from the component analysis, the isoelectric topography and current source density topography are developed to observe dipoles and active origins’ distribution of cortical activity respectively. The results show no significant differences in N100/P200 amplitude and N100 latency between the tinnitus and normal groups (two-tailed Student’s t-test, p > 0.05). There is also, no gross difference of isoelectric topography and current density topography between the two groups.
Most multi-channel recording systems are very expensive. They are usually constructed by duplicating single-channel hardware into multiple copies. Their size, power consumption, and cost increase rapidly as the number of channels multiply. To resolve this problem, the other part of this thesis is dedicated to developing a time-division-multiplexing (TDM) system for multi-channel recording. By utilizing the TDM method, multiple input signals can be conditioned by using a single amplifier and filter stage. The design considerations of the multiplexing amplifier and filter stages are discussed herein. The phenomena in the filter caused by the TDM architecture are the drop of cutoff frequency and the attenuation of gain. The underlying mechanism of the phenomena is depicted and modeled with mathematics, whereby the responses of several types TDM filter were evaluated for understanding the behavior, including first-order low-pass, first-order high-pass, and second-order low-pass filters. The transfer function of such TDM-type filters are derived and verified, in addition to their design rule.
| Identifer | oai:union.ndltd.org:TW/093NTU05530024 |
| Date | January 2005 |
| Creators | Meng-Yi Lin, 林孟儀 |
| Contributors | 趙福杉 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | en_US |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 59 |
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