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Background and Aim: When analyzing the gain-frequency response of a hearing aid, data can be analyzed both clinically and statistically. This study aimed to investigate and compare the gain-frequency responses using statistical and clinical analyses under active digital noise reduction (DNR-on) and inactive digital noise reduction (DNR-off) conditions. Methods: The gain-frequency responses of a hearing aid for one of the most well-known commercial digital hearing aid manufacturers were measured using the FP35 hearing aid analyzer (Frye Electronics Inc., USA) by presenting two types of signals (digital speech and composite noise) at input levels of 65 and 80 dB SPL under the DNR-on and DNR-off conditions. Data analysis was performed both statistically (using Wilcoxon signed rank test) and clinically (using 3 dB difference criterion). Results: A statistically significant difference was found in the gain-frequency responses for all speech and noise input levels between the two conditions; while a clinically significant difference was observed only at noise input levels of 65 and 80 dB SPL. Conclusion: For analyzing the hearing aid performance, both clinical and statistical analyses should be considered. Keywords: Digital noise reduction; gain-frequency response; clinical analysis

Background and Aim: One of the chronic hea­lth problems of the elderly is presbycusis, and one of the most important age-related changes in central auditory processing is dichotic listening deficit. The purpose of this study was to investi­gate the effects of using hearing aids on dichotic listening performance of the elderly with hearing loss by dichotic tests. Methods: In this cross-sectional study, randomi­zed dichotic digit test (RDDT) and dichotic auditory verbal memory test (DAVMT) were performed on 20 seniors with hearing loss (8 male, 12 female) aged 65−80 years. They were divided into two groups of test (with hearing aid, n = 10) and control (without hearing aid, n = 10). They were tested before and two months after the use of hearing aid and the results were analyzed using t-test for two independent variables. Results: There was a significant difference in the total DAVMT score in control group before and after the intervention (p < 0.001) and not in test group, but in terms of right and left ear DAVMT and RDDT scores, showed no significant diffe­rence in any groups. Moreover, there was no sig­nificant difference in the mean DAVMT score of the right ear and the mean RDDT score between groups, but in terms of the total DAVMT score, a significant difference between two groups was reported (p = 0.003). Conclusion: It can be said that the DAVMT has the ability to show adverse effects of hearing loss on recognition function and memory of the elde­rly. Keywords: Randomized dichotic digit test; dichotic auditory verbal memory test; hearing aid; presbycusis

Background and Aim: It is well known that hearing aid fitting is an effective approach to improve the communication ability of hearingimpaired people. In the past, most of the hearing aids were fitted unilaterally rather than bilaterally. Whereas the unilateral hearing aid fitting improves verbal communication partially, it causes late-onset auditory deprivation. The main aim of this study is to investigate the ANL for each ear among the users with unilateral hearing aid experience. Methods: A total of 23 participants were recruited (14 females, 9 males). The mean age was 74.65 years (ranged from 41 to 83). All subjects had bilateral symmetric sensorineural hearing loss. The most comfortable level (MCL), Background Noise Level (BNL), and acceptable noise level (ANL) were measured for ear with amplification experience and ear without experience. Results: MCL, BNL and ANL in the aided ear was 82.22, 73.48 and 8.74 respectively, in addition in the unaided ear the results for MCL, BNL and ANL was 81.78, 72.13 and 9.65 respectively. Comparing the mean values of MCL, BNL and ANL between two ears showed no significant difference. Conclusion: There was not any difference for BNL and ANL measures Keywords: Bilateral hearing loss; acceptable noise level; late onset auditory deprivation; Hearing aid

Background and Aim: One of the tools for ass­essing the vestibulo-ocular reflex (VOR) is using video head impulse test (vHIT). In this test by placing the head at different angles and shaking the head, three semicircular canals of the vestibular system in each ear can be exami­ned separately. The purpose of this study was to investigate the relationship between the low and high velocities of the vHIT test with VOR and its compensatory saccades. Methods: The vHIT test was performed by an examiner in 49 normal individuals aged 23–39 at low and high velocities. All participants had normal hearing, visual, and vestibular systems. Results: Mean gains in the horizontal, anterior and posterior semicircular canals in the right ear respectively were 0.92, 1 and 0.90 and in the left ear 0.93, 0.99 and 0.95 for low velocity and 0.78, 0.92 and 0.79 in the right ear and 0.80, 0.85 and 0.86 in the left ear for high velocity. Also, the number of compensatory saccade at high velocity was higher than those at the low velocity and the latency of compensatory sacc­ade was lower at the higher velocity. Conclusion: In the vHIT test, VOR gain decreases at high velocity that is statistically significant. Also, compensatory saccades are more likely to occur at high velocity with sma­ller delay. Therefore, high-velocity vHIT test is not recommended for the purpose of examining the VOR gain and compensatory saccade.

Background and Aim: Although recent research has revealed the positive effects of bilin­gualism on children's cognitive abilities, little information is available on the relationship bet­ween bilingualism and working memory. Working memory is generally composed of four dis­tinct parts, among which the phonological loop plays an important role in speech and language development, reading skills, and learning. In the present study, bilingual and monolingual stude­nts were compared in terms of auditory-verbal memory performance, using Rey auditory-verbal learning test. Methods: In this cross-sectional study, the auditory-verbal memory performance of 56 monolingual and 55 bilingual students were assessed, using the Persian version of Rey auditory-verbal learning test. The study samples were selected among students in the fifth and sixth grades of primary school. Finally, the scores obtained on the test were compared between the two groups. Results: The mean scores of stages 1-5, 7, and 8 of Rey test were 48.71 (SD=6.71) out of 75, 10.25 (SD=2.29) out of 15, and 10.50 (SD=2.27) out of 15 in monolinguals and 53.54 (SD=5.24), 11.80 (SD=2.13), and 11.98 (SD=1.88) in bilinguals, respectively. There was a statistically significant difference between the scores of the two groups (p