فهرست مطالب ریحانه توفان

Occupational noise is a major cause of hearing loss and tinnitus. In the present study, acoustic characteristics of tinnitus were evaluated and their relation with hearing loss and nervousness was studied. Our study was performed on 56 male workers aged 40 to 56 years including 28 workers with accompanied hearing loss and tinnitus and a long history of working in environments with excessive noise and 28 matched workers with normal hearing. Acoustic characteristics and the effects of tinnitus were assessed by case history, and Mini-Mental State Examination Test was performed for all subjects. In the most cases, tinnitus had high pitch and moderate stable loudness. It was continuous with moderate to high annoying effect and impact on sleep and concentration of individuals often. Significant relation was observed between hearing threshold in 4000 Hz frequency and acoustical characteristics of tinnitus (P<0.002). Tinnitus had impact on nervousness personality of the cases too (p<0.047). Difference between scores of two groups in Mini-Mental State Examination Test was significant (p<0.025). Our study revealed effect of hearing loss and tinnitus on general cognition, and relation between acoustic characteristics of tinnitus with degree of hearing loss and strengthen of nervousness in workers exposed to occupational noise.

Hearing loss and tinnitus are two auditory effects of hearing system damage due to occupational noise exposure. These factors can have non-auditory effects by themselves and impact on brain cognitive performance. In our study، the effect of occupational noise-induced hearing loss and tinnitus on cognition and auditory-verbal memory was investigated. Our study was done on 42 male workers aged 40 to 56 years in three groups of workers with 1) hearing loss، 2) hearing loss and tinnitus and 3) normal hearing. Workers in two first groups had a long history of working in environments with excessive noise، and third group was matched control workers with normal hearing. Hearing impaired persons had symmetrical moderate falling sensory-neural hearing loss in the both ears. For all subjects، Mini-Mental State Examination and Rey Auditory-Verbal Learning Tests were performed in identical conditions. Normal hearing group had higher scores in all stages of the Rey Auditory-Verbal Learning test than two other groups and their means differences in three A1، Sum and Recognition stages were significant (p≤0. 034). Similar finding was observed in the Mini-Mental Examination test too (p≤0. 025). Our study revealed effect of noise induced hearing loss and tinnitus due to prolonged exposure to noise over the limit on general cognition and auditory-verbal memory. Given the preventable nature of auditory and non-auditory effects of occupational noise، administration and control of hearing conservation programs and training of workers can be the suitable and proposed solution.

Dichotic listening means presentation of two different auditory stimuli to each ear simultaneously. This study deals with the development of Persian version of Bergen dichotic listening test and its preliminary results on auditory attention and language laterality in adults with normal hearing. Persian version of the Bergen dichotic listening test was instructed by six consonant-vowel syllables to evaluate three conditions of non-forced attention, attention to right and attention to left ears separately. Then, it was performed on 54 right-handed young adults with normal hearing and the mean age of 23.24 (SD=2.78) years from both genders. Frequency of correct response in the right ear was higher significantly in two conditions of non-forced attention (83.3%) and attention to the right ear (98.1%), and also was higher significantly in the left ear (-79.6%) in attention to the left (p<0.0001). Laterality index was 31.33% in non-forced attention, 73.30% in attention to the right and -37.50% in attention to the left which was significantly different (p<0.0001). Right ear advantage was revealed in non-forced attention that was altered with selective attention to the right and left remarkably result from the effect of top-down processing of brain cortex on bottom-top processing of speech stimulus. These preliminary results showed the performance of Bergen dichotic listening test to test auditory attention and language laterality.

Auditory memory plays an important role in developing language skills and learning. The aim of the present study was to assess auditory verbal memory and learning performance of 18-30 year old healthy adults using the Persian version of the Rey Auditory-Verbal Learning Test (RAVLT). This descriptive، cross-sectional study was coducted on seventy 18-30 year old healthy females with the mean age of 23. 2 years and a standard deviation (SD) of 2. 4 years. Different aspects of memory، like immediate recall، delayed recall، recognition، forgetting rate، interference and learning، were assessed using the Persian version of RAVLT. Mean score increased from 8. 94 (SD=1. 91) on the first trial to 13. 70 (SD=1. 18) on the fifth trial. Total learning mean score was 12. 19 (SD=1. 08)، and mean learning rate was 4. 76. Mean scores of the participants on the delayed recall and recognition trials were 13. 47 (SD=1. 2)، and 14. 72 (SD=0. 53)، respectively. The proactive and retroactive interference scores were 0. 86 and 0. 96، respectively. The forgetting rate score was 1. 01 and the retrieval score was 0. 90. The auditory-verbal memory and learning performance of healthy Persian-speaking females was similar to the performance of the same population in other countries. Therefore، the Persian version of RAVLT is valid for assessment of memory function in the Persian-speaking female population.

Occupational noise is one of the major causes of hearing loss and tinnitus. In the present study, the effect of occupational noise-induced tinnitus on auditory attention was investigated. A sample of 42 man, all workers, ages 40 to 56, participated in the study in three groups of workers with hearing loss, hearing loss and tinnitus, and normal hearing. Workers in two first groups had a long history of working in environments with excessive noise, and third group was matched control workers with normal hearing. For all subjects the Mini-Mental State Examination (MMSE) and the Bergen dichotic listening test were performed in identical conditions. In all three conditions of attention, including non-forced, forced right, and forced left attentions, right ear advantage (REA) was lower in tinnitus and hearing loss group than the two other groups. The difference between the tinnitus and hearing loss groups and the control group was significant in the non-forced attention condition (p<0.047). Furthermore, both groups had poorer result in the MSSE test compared to the control group (p<0.025). Our study revealed effect of noiseinduced tinnitus on selective and divided auditory attention. It seems that tinnitus is affects both both bottom- up and top-down processing of speech stimuli.

The effects of handedness and gender were studied in this research by using Bergen Dichotic listening test, which measures both divided and selective attentions. The Persian version of Bergen dichotic listening test was used to evaluate non-forced attention, attention to right and attention to left ears on 75 young adults, including 54 right-handed and 21 left-handed individuals, with normal hearing in ages ranging from 18 to 30 years old. Right ear advantage (REA) with the mean score of 78.4% and 94.7% in the two conditions of non-forced attention and attention to the right ear, and left ear advantage (LEA) with the mean score of 81.3% in attention to the left ear were obtained. Sex had no effect on the results, but significant difference was found between right and left hand people in non-forced attention and attention to the right (p<0.029). Top-down processing of brain cortex in selective attention modulated bottom-up processing in divided attention task by changing right ear advantage. Our results demonstrated the application of Bergen dichotic listening test to evaluate auditory attention, language laterality and handedness.

The dichotic auditory-verbal memory test (DAVMT) is useful in detecting auditory-verbal memory deficits and differences in memory function between the brain hemispheres. The purpose of this study was to prepare the Persian version of dichotic auditory-verbal memory test and to obtain its results in 18- to 25-year old normal individuals of both genders in Iran. The Persian version of dichotic auditory-verbal memory test like the original one consisted of 18 lists of ten words. The lists were arranged such that 10 words were presented to one ear, with the reverse words simultaneously were presented to the other ear, constituting a dichotic test situation. After preparing the 18 lists, content validity was assessed by a panel of eight experts and then, the words of each list were recorded on CD in a dichotic mode. Thereafter, it was performed on one hundred and ten normal individuals with ages ranging from 18 to 25 years (mean age: 21.3 SD 1.9 years) and the scores were recorded on a specially designed scoring sheet. There was no significant difference between mean scores of 18 lists of the dichotic auditory-verbal memory test. The overall mean of CVI was 96% for the 18 lists and the mean score of dichotic auditory-verbal memory test was 6.5 SD 1.0 in the normal group. Based on the obtained results, the Persian version of dichotic auditory-verbal memory test has a good content validity and can be used in detecting the auditory-verbal memory deficits.

Vestibular-Evoked Myogenic Potentials (VEMP) is a new vestibular function test that assesses the vestibulospinal pathway.Although many studies have investigated different inner ear pathologies by using VEMP, the role of this test in brainstem pathologies and demyelinating processes of central nervous system is still remained to be defined and discussed.The aim of this study was to compare VEMP in multiple sclerosis patients and normal individuals.

We carried out a cross-sectional study in 21 patients (15 female, 6 male) fulfilling diagnostic criteria of clinically definite multiple sclerosis, and 20 normal individuals (15 female, 6 male). ages ranging from 17 to 50 years old.The VEMPs was recorded using 500 Hz short tone burst (STB). The p13 and n23 latencies and p13-n23 peak-to-peak amplitude were the studied parameters.

VEMP results were abnormal in 47.6% of patients. P13 latency and p13-n23 peak to peak amplitude in both ears showed significant difference between the two groups (p<0.05). P13 latency was delayed in 14 ears (of nine patients). VEMPs were unilaterally absent in two patients.

VEMPs thus represent a new method of the brainstem in multiple sclerosis disease. VEMP abnormalities in these patients might be due to impairment in vestibulocollic pathway.