A música é vista principalmente como arte e lazer e também pode exercer um importante papel na educação de adolescentes, trazendo muitos benefícios. Ela não é apenas agradável para a audição, contribui para o bem estar físico e emocional, desencadeiam sensações que podem afetar o humor, a memória, a função cerebral (córtex pré-frontal, raciocínio), frequência cardíaca, metabolismo e sistema imunológico e percepção da dor. No entanto, além dos benefícios da música, quando o indivíduo se expõe de forma inadequada, o prazer proporcionado pode trazer efeitos desagradáveis para a saúde. A indústria da música amplificada, e principalmente a popularização dos dispositivos sonoros portáteis individuais é crescente entre os jovens, tornando a perda auditiva induzida por elevados níveis de pressão sonora entre crianças e adolescentes uma preocupação evidente. Os riscos, para adquirir a perda auditiva dependem de fatores como número de horas de uso dos fones auriculares ou intensidade. A quantidade de intensidade sonora bem como o tempo que se fica exposto a eles são fatores determinantes da capacidade de prejudicar a audição. Embora estes jovens estejam habituados à exposição à música elevada, não possuem conhecimento sobre os danos auditivos futuros que podem ser causados pela exposição, e quando apresentam esse conhecimento, não sabem exatamente como prevenir estes danos e proteger a sua audição. Dessa forma, o objetivo deste estudo foi: Investigar o nível de informação que os adolescentes têm sobre a música amplificada e a saúde auditiva bem como seus hábitos de escuta, investigar a prevalência de zumbido e alterações auditivas em adolescentes de ambos os sexos, e realizar revisão sistemática sobre os artigos relacionados ao tema. 59 adolescentes participaram deste estudo, responderam a um questionário sobre música amplificada e audição. O THI, foi realizado quando relataram zumbido. Realizaram meatoscopia, imitanciometria, audiometria tonal liminar e de alta frequência e logoaudiometria. Nos resultados, a pergunta formulada na revisão sistemática de literatura foi respondida e evidenciou que embora os jovens tenham uma informação prévia dos riscos da música amplificada e a audição, não é uma informação concreta e não demonstram vontade de mudar seus hábitos de escuta. Nos resultados do estudo clínico, embora não tenha sido encontrada perda auditiva, as curvas audiométricas sugeriram uma futura PAIM, e os questionários mostraram que os adolescentes tem uma informação prévia do assunto, ainda fazem o uso incorreto da música amplificada. Levando a concluir que campanhas efetivas e eficientes com informações completas devem ser feitas, de forma que atinja o interesse dos adolescentes e mude o seu comportamento frente à música amplificada, para que não se crie uma geração de jovens surdos. / The music is mainly seen as art and leisure and can bring many benefits on a teenagers education. It´s not just pleasant for hearing but contributes to the physical and emotional wellbeing, triggering feelings that can affect humor, memory, brain function (prefrontal cortex, reasoning) heart rate, metabolism, immunologic system and pain perception. However, besides of its benefits, when the person is improperly exposed to the music, the pleasure can bring unpleasant health effects. The amplified music industry and mainly by the popularization and by the rise of individual portable sound devices between the young people make the hearing loss, inducted by the exposure on high sound pressure level, an evident concern. The risks to acquire hearing loss are dependent on factors like the number of hours using the earphones and intensity. The quantity of sound intensity as well the period of exposure are determinant factors of the capacity to cause hearing harm. Although young people are accustomed to be exposed to high sound pressure level, they have no knowledge about the future harms that can be caused by exposure, and when they understand the risks, they not exactly know how to prevent those harms and how to protect their hearing. Thus, the objective of this study is to investigate the amount of information young people have about amplified music and hearing health as well to understand their hearing habits, investigate the prevalence of tinnitus and hearing changes on young people of both sexes and perform a systematic review of the studies regarding the theme. 59 teenagers have attended this study, answered a questionnaire about amplified music and hearing. The THI was executed for the subjects that reported tinnitus. They were submitted to meatoscopy, immittanciometry, tonal threshold and high frequency audiometry and logoaudiometry. The question raised during the review of the literature was answered by the results that showed that although young people have knowledge about the risks of amplified music and hearing, the information is not concrete and they show no desire to change their hearing habits. Although no hearing losses were detected, the results of the clinical studies, mainly by the audiometric curves, suggests future PAIM and the questionnaires revealed that the adolescents have prior information about the issue but even so, they still incorrectly use the amplified music which bring us to the conclusion that effectives and efficiency campaigns with complete information should be done to reach teenagers interests with the purpose to change their behavior regarding amplified music to avoid a future generation of deaf adolescents.

Background: Wind turbines are a form of renewable energy, which generate electricity from wind energy, a practice dating back over 100 years. More recently, large-scale wind energy developments have started to employ one or several industrial wind turbines, which produce the majority of wind energy in Ontario. The production of electricity from the movement of industrial wind turbine motor blades creates both mechanical and aerodynamic noise. This type of environmental noise is a growing public health concern, especially for residents living close to industrial wind turbines. A body of evidence now exists to suggest that industrial wind turbine noise can impair health and contribute to annoyance and sleep disturbance. However, in Ontario, little is known about how industrial wind turbines impact people living in their vicinity. Objectives: This investigation was a cross-sectional study involving eight Ontario communities that contain greater than ten industrial wind turbines. The objectives of this study were to explore the association between proximity to industrial wind turbines and self-reported health effects, specifically quality of life (both physical and mental health) and sleep disturbance, in residents living close to wind turbines. Dose-response relationships were also explored in an attempt to investigate acceptable exposure levels and appropriate setback distances for industrial wind turbines. Methods: Eight wind farms in Ontario were selected for analysis. For this cross-sectional study, the ???Quality of Life and Renewable Energy Technologies Study??? survey was used to measure the impact of industrial wind turbines on health. Using Canada Post???s Unaddressed Admail Service, surveys were sent to 4,876 residences near industrial wind turbines in these eight communities. Survey responses were sent back to the University of Waterloo and data from the surveys were used for analysis. Descriptive analyses were performed and multiple regression models were run to investigate the effect of the main independent variable of interest (distance to nearest industrial wind turbine) on the various outcome variables. Descriptive statistics, including means and standard deviations were performed on a number of dependent and independent variables including age, sex, time in home, number of industrial wind turbines within 2,000 meters and sleep and health outcomes. Results: In total, 412 surveys were returned (8.45% response rate); 16 of these survey respondents did not provide their home address. Therefore, 396 surveys were included in the analysis. The mean self-reported distances of survey respondents to wind farms was 2,782 meters +-3,950 meters (range: 0.40-55,000 meters). The mean calculated distance from residence to the closest industrial wind turbine was 4,523 meters +-4,420 meters (range: 316-22,661 meters). The difference between the calculated and perceived distance measurements was statistically significant (P<0.001) with survey respondents reporting that they live, on average, 1,741 meters closer to wind farms than they actually do. The relationship between Pittsburgh Sleep Quality Index and ln(distance) was found to be statistically significant (P=0.01) when controlling for age, gender and county, meaning that as distance increased (move further away from an industrial wind turbine), Pittsburgh Sleep Quality Index decreased (i.e. sleep improved) in a logarithmic relationship. Among the eight Wind Turbine Syndrome index variables, the relationship between vertigo and ln(distance) was statistically significant (P<0.001) when controlling for age, gender, and county. Additionally, the relationship between tinnitus and ln(distance) approached statistical significance (P=0.08) when controlling for age, gender and county. Both vertigo and tinnitus were worse among participants living closer to industrial wind turbines. Conclusion: Study findings suggest that industrial wind turbines could have an impact on health. Using a sample of rural Ontario residents (although not necessarily representative of the target population), this study explored the quality of life (both physical and mental health) and sleep disturbance of residents living in the vicinity of industrial wind turbines. However, because of study limitations, there are many questions still to be answered before firm conclusions can be drawn. Based on the findings of this study it is recommended that further studies be carried out to examine the effects of low-level stressors, such as industrial wind turbine noise, on health. Specifically, study findings suggest that future research should focus on the effects of industrial wind turbine noise on sleep disturbance and symptoms of inner ear problems. Although the study findings could suggest that there is a possible association between various health outcomes and how far someone lives from an industrial wind turbine, it is important to remember that there are limitations to these conclusions.

M.Tech. / Hypertension or elevated blood pressure is an initiator and promoter of cardiovascular disease and end organ damage. Primary or essential hypertension is an elevated blood pressure due to an unknown or unidentifiable pathology. Secondary hypertension may be caused by underlying pathology or certain medication. Although a number of allopathic drugs are available, hypertension may remain uncontrolled despite lifestyle changes combined with adequate allopathic treatment. This is termed as refractory hypertension. Poor patient compliance, inadequate diuretic therapy, inappropriate drug combinations, and obesity are the leading causes of uncontrolled or refractory hypertension. Crataegus oxyacantha θ is a homoeopathically prepared mother tincture (θ) that has been clinically used to treat hypertension and cardiovascular complaints. However there is insufficient research to confirm its efficacy in the treatment of hypertension. The aim of this study is to ascertain the efficiency of Crataegus oxyacantha θ in the treatment of refractory hypertension in adult males aged between thirty-five and sixty-five years, currently taking allopathic treatment, namely Angiotensin-Converting Enzyme inhibitors combined with a diuretic, and to evaluate the effect of Crataegus oxyacantha Ө on associated symptoms of hypertension. These include headaches; palpitations; vertigo; blurred vision and tinnitus. The study was a placebo controlled double-blinded trial that extended over a period of 12 weeks. Thirty male participants between the ages of thirty-five to sixty-five, that were pre-diagnosed with refractory hypertension for a minimum of two years with a fluctuating blood pressure reading above 150/95 mmHg and currently on allopathic medication i.e. ACE-inhibitor with a combined diuretic were recruited for the study by means of advertisements placed at the University of Johannesburg health clinic, pharmacies and community clinics. Participants were randomly placed in either the experimental or the control group. Participants meeting the inclusion criteria underwent a physical examination and consented to the study (Appendix A). The participants blood pressure was measured on both arms as advised by Milne in the South African hypertensive guidelines 2003 (Annexure A), at the first visit and for two consecutive mornings in order to obtain a baseline reading. He was randomly assigned in either the experimental or the control group. The control group received a 50ml bottle of the 20% alcohol placebo and the experimental group received a 50ml bottle of the homoeopathic remedy, Crataegus oxyacantha θ. He was instructed to take 10 drops in 125ml water twice daily after meals. During the trial period the participant’s blood pressure was assessed every 2 weeks against the measured baseline readings for a period of 12 weeks. The severity of the following symptoms was assessed every 2 weeks, headaches; palpitations; vertigo; blurred vision and tinnitus and other symptoms that he may have experienced. These results were graded and recorded on the progress form (Appendix C). The data obtained from the participants was analysed using descriptive statistics (frequencies and percentages). The blood pressure of the experimental group was compared to the control group as obtained at the first consultation and each of the six follow-up visits. Groups were compared using the Chi-Square test and the Non Parametric Mann Whitney U test. Statistical analysis showed significant differences, P <0.05 for the systolic blood pressure between the experimental and control group. There was a significant decline in the diastolic blood pressure of the experimental and the control group. The diastolic pressure of the control showed a significant decline between day one and week six, however remained constant from week six to week twelve. This implies that the placebo may have provided some benefit towards the lowering of diastolic blood pressure in adult males. The associated symptoms were investigated and the results obtained indicate that headaches and blurred vision remained a constant mild symptom that was experienced throughout the twelve week trial period. Due to the statistical difference between the experimental and the control group in favour of the experimental group, the null hypothesis was rejected. Preliminary findings suggest that Crataegus oxyacantha Ө, is effective in reducing elevated systolic and diastolic blood pressure in adult males with refractory hypertension, however more research over a longer period of time is needed to confirm theses findings.

碩士 / 長榮大學 / 職業安全與衛生研究所 / 97 / This study investigated the occupational injury factors of workers in Municipal Refuse Incineration Plants (MRIP) by questionnaire way to 501 workers in 10 large-scale MRIP. The questionnaire content includes personal background, working duty, personal safety & health protection, safety training, hazard factors, occupational injury types, injury spots, injury intermedium, occurred frequency, occurred reasons and so on, To analyzes the relevance of MRIP workers to suffer from the occupational injury factors, then drafts the precaution to prevent the occupational injuries. It was found that the participants expressed once to suffer from the biological hazard approximately 26%, the main symptom were skin disease and eye disease, to suffer from the chemical hazard approximately 35％,the main symptom were odor and eye irritation, to suffer from the physical hazard approximately 26％,the main symptom were the heat exhaustion, the tinnitus, the hearing loss, the joint pain and so on, to suffer from the human factor engineering hazard approximately 40％, the main symptom were the muscle skeleton injury or the pain and the working pressure , to suffer from the accident injury approximately 31％, mainly was injured the spot for the hand, the foot, the leg, another coming and going to work Once had the traffic accident on the way approximately 20%. By way of the crossover analysis demonstrated the work period of service and the biological hazard have the relevance, The working duty and the biological hazard, chemical hazard , physical hazard and the accident injury have the relevance, The safety and health training has the relevance with each kind of hazard, The personal safety protection and the biological hazard, chemical hazard, accident injury and so on have the relevance, And the working duty, the safety and health training and the personal safety protection with suffering the occupational injuries to have obviously related. The results demonstrated that the proportion of participant suffers from each kind of occupational injury to reach as high as 30% equally, suggested that each MRIP should adopt the essential working environment improvement and the protective measure, to strengthen the safety and health training and the personal safety protection management, and expect to reduce the occurrence of occupational injuries.

Doctor Educationis / Ototoxic induced hearing loss is a common adverse event related to aminoglycosides used in Multi Drug Resistant -Tuberculosis treatment. Exposure to ototoxic drugs damages the structures of the inner ear. Symptomatic hearing loss presents as tinnitus, decreased hearing, a blocked sensation, difficulty understanding speech, and perception of fluctuating hearing, dizziness and hyperacusis/recruitment. The World Health Organization (1995) indicated that most cases of ototoxic hearing loss globally could be attributed to treatment with aminoglycosides. The aim of the study was to determine the proportion of DR-TB patients initiated on treatment at three decentralized sites during a defined period (1st October to 31st December 2015) who developed ototoxic induced hearing loss and the corresponding risk factors, whilst receiving audiological monitoring with an extended high frequency audiometer (KUDUwave). A retrospective cross-sectional study was conducted. Cumulatively across the three decentralized sites, 69 patient records were reviewed that met the inclusion criteria of the study. The mean age of the patients was 36.1, with a standard deviation (SD) of 10.7 years; more than half (37) were female. Ototoxicity , a threshold shift, placing patients at risk of developing a hearing loss was detected in 56.5% (n=39)of patients and not detected in 30.4%(n=21).The remaining 13,1% (n=9)is missing data. As a result, the regimen was adjusted in 36.2% of patients. . From the 53 patients who were tested for hearing loss post completion of the injectable phase of treatment, 22.6% (n=12) had normal hearing, 17.0 % (n=9) had unilateral hearing loss, and 60.4% (n=32) had bilateral hearing loss. Therefore, a total of 41 patients had a degree of hearing loss: over 30% (n=22)had mild to moderate hearing loss, and only about 15% (n=11)had severe to profound hearing loss. Analysis of risk factors showed that having ototoxicity detected and not adjusting regimen significantly increases the risk of patients developing a hearing loss. The key findings of the study have shown that a significant proportion of DR-TB patients receiving an aminoglycoside based regimen are at risk of developing ototoxic induced hearing loss, despite receiving audiological monitoring with an extended high frequency audiometer that allows for early detection of ototoxicity (threshold shift).

Magister Public Health - MPH / Ototoxic induced hearing loss is a common adverse event related to aminoglycosides used in Multi Drug Resistant -Tuberculosis treatment. Exposure to ototoxic drugs damages the structures of the inner ear. Symptomatic hearing loss presents as tinnitus, decreased hearing, a blocked sensation, difficulty understanding speech, and perception of fluctuating hearing, dizziness and hyperacusis/recruitment. The World Health Organization (1995) indicated that most cases of ototoxic hearing loss globally could be attributed to treatment with aminoglycosides. The aim of the study was to determine the proportion of DR-TB patients initiated on treatment at three decentralized sites during a defined period (1st October to 31st December 2015) who developed ototoxic induced hearing loss and the corresponding risk factors, whilst receiving audiological monitoring with an extended high frequency audiometer (KUDUwave). A retrospective cross-sectional study was conducted. Cumulatively across the three decentralized sites, 69 patient records were reviewed that met the inclusion criteria of the study. The mean age of the patients was 36.1, with a standard deviation (SD) of 10.7 years; more than half (37) were female. Ototoxicity , a threshold shift, placing patients at risk of developing a hearing loss was detected in 56.5% (n=39)of patients and not detected in 30.4%(n=21).The remaining 13,1% (n=9)is missing data. As a result, the regimen was adjusted in 36.2% of patients. . From the 53 patients who were tested for hearing loss post completion of the injectable phase of treatment, 22.6% (n=12) had normal hearing, 17.0 % (n=9) had unilateral hearing loss, and 60.4% (n=32) had bilateral hearing loss. Therefore, a total of 41 patients had a degree of hearing loss: over 30% (n=22)had mild to moderate hearing loss, and only about 15% (n=11)had severe to profound hearing loss. Analysis of risk factors showed that having ototoxicity detected and not adjusting regimen significantly increases the risk of patients developing a hearing loss. The key findings of the study have shown that a significant proportion of DR-TB patients receiving an aminoglycoside based regimen are at risk of developing ototoxic induced hearing loss, despite receiving audiological monitoring with an extended high frequency audiometer that allows for early detection of ototoxicity (threshold shift).

碩士 / 國防醫學院 / 海底醫學研究所 / 93 / ABSTRACT Middle ear barotrauma is a frequently seen complication during exposure to abnormal environmental pressure such as diving activities and during hyperbaric oxygen therapy. The incidence of middle ear barotrauma has been linked to the function of Eustachian tube (E-tube). The patency of E-tube may possibly change due to deviation from upright posture underwater. Therefore, the study aimed to examine E-tube function at upright and prone positions. Further, the correlation of E-tube function and incidence of middle ear barotrauma was evaluated. The swallowing tests of E-tube function (with or without pinching the nose) were performed in thirty healthy volunteers in both upright and prone positions. The incidence of middle ear barotrauma was evaluated in 56 patients (111 ears) receiving hyperbaric oxygen therapy (HBOT). Tympanogram, E-tube function (by swallow test), and ability to perform Valsalva manuver were recorded prior to HBOT. Correlations between these parameters and incidence of middle ear barotrauma were made. Our results showed that postures did not affect the peak pressure changes of tympanogram during swallow test. Further, the ratio of E-tube that show good function was also not changed by postures. We did notice that pinching the nose while perform swallow movement exerted a larger peak pressure shift in tympanogram. Among the 111 ears that received HBOT for 1 to 40 sessions (with an average of 13 sessions), 54 ears suffered from middle ear barotraumas. The overall incidence was 48.6%. The occurrence of middle ear barotrauma was mostly observed in the first 5 treatment sessions with the first treatment carring the highest incidence (32/111, 32%). The symptoms of middle ear barotrauma in decreasing orders were ear fullness (54%), otalgia (41%), tinnitus (20%), impaired hearing (11%). The patterns of tympanogram, E-tube function, and ability to perform Valsalva manuver did not show significant correlation with middle ear barotrauma. Among the patients that could equalize middle ear pressure by Valsalva manuver, lack of performing Valsalva manuver during HBOT showed a significantly higher incidence of barotrauma than those that did perform it. We conclude that whether the subjects do perform middle ear pressure equalizing techniques is an important factor in determining the incidence of middle ear barotrauma. We suggest health education, training in middle ear pressure equalizing techniques and performing these techniques during pressure changes are important in preventing middle ear barotrauma.

碩士 / 台北醫學院 / 公共衛生學研究所 / 87 / Health status and working environment of veterinarians have been disregarded in Taiwan. Thus, 1,317 veterinarians in animal hospitals and clinics were surveyed by mailed self-administered questionnaires with follow-up of non-respondents between December 1998 and April 1999. The overall response rate was 30.5% (402/1,317) and the effective response rate was 29.6% (390/1,317). The average age of respondents was 37.3 years old, and the major practitioners were male (90%). The eye symptoms of respondents were eye itching (48.9%) , eye drying (42.1%), and sight weakness (38.8%). Ear symptoms were tinnitus (24.1%), dizziness (2.9%), and loss of clarity in hearing (18.5%). Respiratory symptoms were stuffing nose/nasal mucus/sneezing (86.6%), cough with phlegm (73.7%), and hack (52.6%). Allergic rhinitis (20.8%) was the major respiratory disease, which were diagnosed by medical doctors. The predominant cutaneous symptoms of respondents were skin itching (59.7%), skin eruptions (44.1%), and skin redness (36.4%). Allergic contact dermatitis (8.4%) and irritant dermatitis (5.8%) caused most cases of skin diseases. Hands were the most commonly affected parts of skin. 36.6% of respondents suffered digestive symptoms/diseases, and diarrhea (20.7%) was the most frequent one. 64.8% of respondent suffered musculoskeletal sores, mostly on lumbar, neck, and shoulder. 59.5% of respondents considered that they had long work time (70.7 hr/wk) compared to 46.8 hr/wk, the average work time of employees in Taiwan. The incident rate of animal attack was 2.1/person/month, and hand injuries (97.8%) were most common. The needlestick injury rate was 6.3 sticks/person/year, compare to 1.2-2.8 sticks/person/year of nurses. Animal attack, needlestick, and radiation were considered to be the more frequent risk factors by respondents with less work experience. Respondents with higher education status, less work experience, or younger age exhibited higher frequency of utilizing X-ray, ultrasonic waves, antineoplastic drugs, anesthetic gas, formaldehyde, and developer when compared with workers with lower education status, more work experience, or older age. The most commonly zoonotic diseases which respondents have been diagnosed were cat scratch fever, ringworm, and leptospirosis. However, ringworm and toxoplasmosis were the most frequently reported zoonotic infections among our respondents.

碩士 / 長庚大學 / 醫療機電工程研究所 / 100 / Hearing loss induced by the central auditory pathways neural hyperactivity, the spontaneous motivation from auditory cortex may be one of reasons about tinnitus. But the hyperactivity caused by acoustic trauma is still unclear. Study shows heat shock protein in auditory cortex of rats has been changed when noise exposure, it also makes the difference on gene expression. However, the pervious examine needed to invasively adopting sacrifice of animals in order to observe the difference between the normal hearing rats and the hearing impairment rats. So, we try to find a non-invasive way to observe the difference between normal and hearing loss rats. Using sodium magnetic resonance imaging is the best choice to observe organization. Sodium ion is 0.2% weight of human body, this ion is not only helping us to balance plasma osmotic pressure, but it is also the key of action potential. Every organization has their unique T1, T2 relaxation times. In this study, we measured the T1, T2 relaxation times to find the characteristic of auditory cortex. The National Taiwan University’s Bruker 7T BioSpec 70/30 USR Preclinical MRI System was utilized to acquire T1, T2 relaxation times of phantom and rats. The sequence was FLASH, and the study was separated into two parts. The 140mM NaCl liquor was used in the phantom, which is the concentration of a normal rat’s brain, and the animal model were only contain the female Sprague Dawley rats weighted between 250 - 300g. The T1, T2 relaxation times of 140mM NaCl liquor was measured successfully, that the T1 relaxation time is 56.02 ± 2.88 ms and T2 relaxation time is 52.31 ± 2.74 ms. We found that when using the Flash sequence to investigate the phantom experiment, we needed to be award on the effect from flip angle, FA at T1 relaxation time, and the number of excitations, NEX at T2 relaxation time. The values of T1and T2 at the rats’ for auditory cortex were 38.91 ± 8.54 ms and 22.18 ± 6.95 ms, respectively. This study is the first development of technologies on sodium MRI to find T1 and T2 relaxation times at auditory cortex in normal rats. And the further studies could focus on the T1 and T2 of the auditory cortex of the rats with noise exposure.

[Truncated abstract] The mammalian inner ear is innervated by the efferent olivocochlear system which is divided into medial and lateral systems. In anaesthetised animals, medial olivocochlear (MOC) axons can be electrically stimulated at the floor of the IVth ventricle. MOC stimulation suppresses the spontaneous activity and sound-evoked responses of primary afferents by its actions on outer hair cells. Effects of MOC stimulation have been also reported on responses of neurons in the cochlear nucleus, the first central auditory center receiving cochlear input. However, very little is known about the net results of MOC effects in higher order neurons. This issue was investigated by electrically stimulating MOC axons at the IVth ventricle and recording extracellular single unit activities in the central nucleus of the inferior colliculus (CNIC) of anaesthetised guinea pigs. For the first part of the study, anatomical and neurophysiological studies were carried out to establish that the focal midline MOC stimulation can selectively stimulate MOC axons without any current spread to adjacent ascending fibers. The MOC stimulation and CNIC recordings were then carried out in a series of experiments that included normal hearing animals, animals treated acutely with gentamicin (in which the acetylcholine-mediated peripheral suppression of the olivocochlear efferents is selectively eliminated) and partially deafened animals. ... However, in other CNIC neurons, effects could not be so explained, showing either additional suppression or even marked excitatory effects. (4) MOC stimulation also suppressed the spontaneous activity of CNIC neurons in normal hearing animals. When similar efferent stimulation was carried out in partially deafened animals, the abnormally high spontaneous activity of some CNIC neurons in the deafened frequency regions was also transiently suppressed by MOC shocks. The results from this study clearly demonstrate that the MOC system can modulate the responses of midbrain neurons in a more complex manner compared to the effects seen in the periphery. The more complex effects seen for responses to tones in quiet and in noisy background are likely to result from a complex interplay between altered afferent input in the cochlea and central circuitry. In addition, the ability of MOC efferents in suppressing the normal and abnormal spontaneous activity in the midbrain also could have implications for the role of the descending system in the pathophysiology and treatment of tinnitus.