碩士 / 國立成功大學 / 醫學工程研究所 / 91 / Most people have tinnitus experiences with various degree, and one-third of the elderly are suffered from tinnitus. The statistical data of American Tinnitus Association shows that there are forty-one million tinnitus patients in America. Twelve million patients have severe tinnitus. Unfortunately, most conventional treatments fail to improve the symptoms of tinnitus. Many patients feel aborted, confused and depressed. Until 1980, neurophysiologist Pawel Jastreboff and Dr. Vernon have proposed a Tinnitus Retraining Therapy and a Tinnitus Masking treatment for the tinnitus, respectively. These therapies consist of clinical consultation by physicians and applying noise generator for rehabilitation treatment. Based on the plasticity and habituation of neuron, the implementation of noise generator is to accelerate the period of habituation to improve the symptoms of tinnitus.
Most imported commercial noise generators provide primarily broadband noises for the treatment ; unfortunately, the devices and their corresponding treatment are without considering the clinical evidence that among 70% of tinnitus patients are complicated with hearing loss. Except white noise with only volume adjustment from noise generators providing inefficacious outcomes for some tinnitus patients, it always takes a prolong period for treatment and even is at high risk for hearing loss damage. Moreover, the imported noise generators are too expensive for many domestic patients in need to obtain medicinal treatment.
Recently, Advanced technology of digital signal processing in both hardware makes the implementation of many complex algorithms becoming possible. Based on the concept and underlying mechanisms of Tinnitus Retraining Therapy and Tinnitus Masking, this research project, which applies theories of statistical digital signal processing and modeling, is aimed to develop and establish a PC-based platform for evaluation and rehabilitation of tinnitus. This platform, which provides the measuring and evaluation of physical parameters of hearing state and tinnitus, is able to prescribe the customized noise of treatment with specified spectrum.
The evaluation and rehabilitation platform for tinnitus treatment are completely developed with four main modules including PTA module, narrow-band noise production module, tinnitus-sound approaching module, and noise with specified spectrum production module. There are pure tones of 250, 500, 1k, 2k, 4k and 8k Hz in the PTA module to measure subject’s hearing thresholds. In narrow-band noise production module, it provides 18 sub-bands covering from 20 to 20k Hz of noise to evaluate the frequency band ,minimum masking level(MML) and mixing point(MP) of tinnitus. The tinnitus-sound approaching module offers noise with adjustable bandwidth to resolve the limitation of fixed band of narrow-band noise production module. The noise with specified spectrum production module produces the noise of tinnitus rehabilitation and treatment with specified spectrum according to the measured hearing parameters.
The calibration and testing of the platform system has been conducted . The results of frequency calibration of pure tones indicate that all the relative errors for 250, 500, 1k, 2k, 4k and 8k Hz are less than 0.1%. The mapping table of setup volume in this system to sound level meter output is also conducted. Output volume of pure tones or noise of the platform could be converted to be in dB SPL by this mapping table. The calibration results of volume output of the system relative to sound level meter show that the mean value of correlation coefficients between nominal value and system output volume is 0.9724±.3445. This PC-based platform could provide the noise with bandwidth ranging from 20 to 20k Hz and volume up to 117.58 dB SPL for evaluation and rehabilitation of tinnitus.
A pilot study is conducted to clinically implement the system for measuring and evaluation of tinnitus patients. A total of 21 tinnitus patients are in involved at this stage. For the PTA measurements, 7 of 21 patients have show high frequency loss type. 10 of 21 patients are Left-side tinnitus . There is no obvious trend in the distribution of tinnitus frequency, it might be resulted from small size of sampling. Using this platform 20 of 21 patients are frequency matching in tinnitus, and 15 of 20 patients are volume matching. The mean and standard deviation of volume values for MML and MP are 97.27±18.8 dB and 86.18±16.7 dB ,respectively. This system provides the prediction capability for the value of MP through regression analysis of MML and MP with equation y=.839x+7.266 (x : MML; y : MP), correlation coefficient=0.972 at p<.05. This platform works well so far by the results of clinic trial stage and responses of subjects.
The future system research and development are recommended as following: (1) to download the customized noise to MP3 player as a noise generator and to setup the experimental group with customized-noise generator and control group with imported white noise generator for the comparison and analysis of the results of both methods; and (2) to implement the noise generator by DSP chip with linear prediction coefficients calculated by this platform system.
| Identifer | oai:union.ndltd.org:TW/091NCKU0530026 |
| Date | January 2003 |
| Creators | Chun-Chou Cheng, 鄭圳州 |
| Contributors | Kao-Chi Chung, 鍾高基 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 92 |
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