mitra rezapour

Tinnitus is a perception of sound in ears or head in the absence of any external stimuli. Despite its high prevalence in various age groups, tinnitus has still no effective treatment because its physiological and pathological mechanisms have remained unknown. Since the study of cellular-molecular mechanisms of tinnitus production and stability in human is not feasible, animal models have been used to shed some light on tinnitus induction and propagation mechanisms. This study reviewed some of these research studies. The present review article is based on articles published during 1967-2018 in which keywords such as “salicylate,” “noise,” “tinnitus in the animal model,” and “tinnitus mechanism” were used. These articles were searched in databases such as Science Direct, Google Scholar, PubMed, and Scopus. Despite differences in the mechanisms of tinnitus induction, the structural changes initiated from the cochlea and continued to cortex reflect the extent of the affected regions in the creation, development, and preservation of tinnitus. Animal models (exposed to noise or ototoxic drugs such as salicylate) are ideal tools for studying tinnitus and understanding the details of its propagation and unknown mecha nisms.

Children with reading disorder show problems in auditory attention and cerebral dominance that can be assessed using dichotic listening techniques. The aim of the present study was to assess and compare auditory attention (divided and selective) and language lateralization between normal and reading disabled children. The current cross-sectional study was performed on 30 normal children and 30 children with reading disability of 8 to 10 years old with normal peripheral hearing and strong right-handedness. First, participants were divided into three age groups of 8, 9, and 10 years old. Then, the mean scores of right and left ear responses and laterality index values were calculated and compared in three divided and selective attention conditions for all age groups using repeated measures test. Comparison of the scores showed statistically significant differences between the mean scores of right and left ears responses and laterality index values between the two groups in all age groups and three condition tests (p-value< 0/05). The results of the present study showed poor performance of children with reading disorder in dichotic digit test in both divided and selective attention conditions.

One of the most important capabilities of central auditory nervous system is dichotic listening processing, which undergoes changes with aging, similar to peripheral hearing. The results of the studies about comparison of functional asymmetry of cerebral hemispheres between musician and non-musician elderlies reveal advantages of musician old age in dichotic listening processing. In the present investigation, functional asymmetry of cerebral hemispheres is investigated in dichotic listening musician and non-musician elderlies with normal hearing using dichotic digit test.
Material and The current cross-sectional study was performed on 40 right-handed musician (N= 20) and non-musician (N= 20) elderlies aged 60 to 80 years with normal hearing using the Persian version of the dichotic digit test. Data was analyzed running independent t test and man-whitny test. Finally, the results of right and left ears were compared in Non-Forced Attention (NF), Forced Right (FR), and Forced Left (FL) attention conditions.
Comparison of dichotic digit test results in divided attention condition showed significant difference between the two groups (p-value The results of the present study confirmed better function in musician elderlies compared with non-musician elderlies in divided attention and competitive environment particularly in FL attention condition. In fact, musician elderlie's desire to acquire information through both ears in noisy places, unlike their non-musician counterparts. Finally, musician elderlies showed lower hemispheric asymmetries with higher scores obtained in dichotic digit test.

All subjects suspected of Central Auditory Processing Disorder (CAPD) were previously tested by free recall dichotic digits test (DDT). The study objective was normalization and reliability evaluation of two-pair DDT in 750 native Persian subjects aged 8 to 12 years.
Materials: A total of 750 subjects were divided into five age groups varying between 8 years and 12 years and 11 months old. Each age group had 150 subjects. DDT was tested in free recall condition. For evaluating DDT test-retest reliability, 300 participants (60 subjects in each age group) were tested again after one month.
Right and left ear mean score increased from 71.68(±2.19) and 58.51(±1.71) in the 8-year-old group to 90.26(±1.96) and 88.38(±1.36) in 12-year-old group, respectively. The mean Right Ear Advantage (REA) decreased from 13.16(±2.58) in the 8-year-old group to 1.88(±2.49) in the 12-year-old group. A high stability was observed between test-retest results (P Persian version of two-pair dichotic digits exhibited proper reliability for evaluating 8 to 12-year-old subjects, and the study results can be used for evaluating the dichotic hearing function in subjects of the same age group.

Most of the elderly have trouble in speech understanding especially in the presence of competitive sounds compared with the young and this is partly as a result of (central) auditory processing disorder, particularly dichotic hearing problems. The aim of the current study was investigating and comparing the dichotic hearing processing in old and young age groups by two-pair dichotic digit test. This cross-sectional study was implemented by Persian version of two-pair dichotic digit test on 28 young subjects (18-28 years old) and 27 old subjects (60-80 years old) from both genders. All participants had normal peripheral hearing and right-handedness. Next, right and left ear results were compared in focused and divided attention conditions. Dichotic digit test scores in 3 attentional conditions in two age groups showed significant difference (p-value<0.001). There was dichotic hearing dysfunction in old age group in all the three attentional conditions, especially in left ear attention. Ear asymmetry was larger for the elderly.

Aging is accompanied with changes in cognitive capacities. In spite of advances in neural imaging technologies, there is not a straightforward method to observe cognitive functions. For assessing brain functions, researchers mainly use psychometric tests. The aim of this study was using consonant-vowel (CV) dichotic test as a non-invasive behavioral test for auditory attention (focused and divided attention) and language laterality evaluation in young and old age groups. In the present cross-sectional study, Persian version of consonant-vowel dichotic test was performed on 28 young subjects within 18-28 and 27 old subjects within 60-80 year-old age range of both genders. All subjects had normal peripheral hearing and were right-handed. Right and left ear scores were compared under three different attention conditions: divided or non-forced attention, attention to the right ear, attention to the left ear. In non-forced condition there was no significant difference for the right ear score between the two age groups (p=0.97) but the left ear score was statistically different (p≤0.001). In addition, there was a significant difference between two ears’ scores in attention to right/left ear for both age groups (p≤0.001). In the older group under divided attention condition, the left ear score was lower than the younger group and they had problem in paying attention especially to the left ear stimuli. In the older group, ear asymmetry for consonant-vowel dichotic test score was higher than the younger one.