Editorial

Background and Aim: Tinnitus is defined a phantom sound percept. Few studies have examined the occurrence of synaptopathy in tinnitus patients utilizing a battery of tests that indicate synaptopathy. This study aimed to investigate the role of synaptopathy in tinnitus production and compare the various characteristics of the auditory brainstem response (ABR) test and electrocochleography (ECochG) in normal-hearing people with and without tinnitus.
Methods: This cross-sectional study was conducted on 34 normal-hearing individuals, 20 without tinnitus as controls (11 females and 9 males) and 14 with tinnitus (8 females and 6 men). The test components (amplitude, growth and slope of wave I, V/I ratio, action potential (AP) amplitude, and summating potential (SP)/AP) ratio were recorded during the ABR and ECochG tests for each subject.
Results: The control group had higher mean values of amplitude, growth and slope of wave I, and AP amplitude compared to the tinnitus group, and this difference was statistically significant (p<0.05). The mean V/I ratio and SP/AP ratio were lower in the control group than in the tinnitus group, and this difference was statistically significant (p<0.05).
Conclusion: The significant difference in the parameters of ABR and ECochG tests between normal-hearing people with and without tinnitus indicates that these parameters can be used to evaluate the presence of synaptopathy in tinnitus patients. These findings suggest the need for proper interpretation of the results of ABR and ECochG tests in tinnitus patients with a focus on the parameters indicating synaptopathy.

Background and Aim: Noise tolerance and performance in noisy environments are influential factors of hearing aid use in people with hearing loss. One of the causes of hearing loss is Meniere’s disease (MD), which affects speech perception in noise. Acceptable noise level (ANL) is a test that measures the maximum tolerated background noise level (BNL) while listening to the running speech. Since the effect of MD on ANL needs further study, the present study aims to examine the ANL test results in people with unilateral MD, and compare the results between the two ears.
Methods: This cross sectional study conducted on 33 individuals with unilateral MD (21 females and 12 males) aged 32–60 years who had the disease for at least one year, who participated in this study. Their most comfortable level (MCL), BNL, and ANL in both ears were then evaluated.
Results: The mean MCL and BNL were significantly different between the two ears, where they were higher in the affected ear than in the contralateral ear. There was also a significant difference in the ANL results between the two ears. In the affected ear, a statistically significant relationship was reported between the ANL and the average hearing thresholds at frequencies of 250, 500, and 1000 Hz.
Conclusion: MD affects the ANL in the affected ear and causes a deterioration in its level and speech perception in noise.

Background and Aim: Early detection of auditory processing disorders (APD) is essential for preventing learning and educational problems in school-aged children. It is crucial to take into account the comorbidity with APD, as well. The goal of APD screening is to obtain the basic information about those with auditory disorders to be referred for further evaluation. This study aimed to identify the elementary school students at risk of APD in Tehran, Iran.
Methods: Participants were the parents of 536 children selected from 11 elementary schools in four districts of Tehran city. The schools in each district were selected by a random clustering method. The auditory system of students was first evaluated. The parents were then asked to complete the Persian version of the auditory processing domain questionnaire (APDQ).
Results: The prevalence of APD was 3.3% in girls and 8.3% in boys and the difference between them was statistically significant (p=0.021). The overall prevalence of APD was 4.6% based on the cut-off points of four APDQ domains, with a male-to-female ratio of 2.6.
Conclusion: It is necessary to screen APD in school-aged children to minimize learning and educational problems in them. Moreover, there is a need for developing screening methods to provide timely detection and appropriate intervention for those at risk of APD.

Background and Aim: Musical training has shown to bring about superior performance in several auditory and non-auditory tasks compared to those without musical exposure. Distortion product otoacoustic emissions (DPOAE) input-output function can be an indicator of the non-linear functioning of the cochlea. The objective of this study was to evaluate and compare the differences in the slope of DPOAE input-output function in individuals with and without musical abilities.
Methods: Twenty normal-hearing individuals were considered in the age range of 18–25 years. They were divided based on the scores obtained on the questionnaire of musical abilities, as individuals with and without musical abilities. DPOAE input-output function was done for each of the two groups. The slope of the DPOAE input-output function was compared at different frequencies between the groups.
Results: The results of the Mann Whitney test revealed that the slope was significantly steeper at 2000, 3000, 4000 and 6000 Hz in individuals with musical abilities. There was no significant difference in slope at 1000 and 1500 Hz.
Conclusion: The increased steepness of the slope indicates a relatively better functioning of the cochlea in individuals with musical abilities. The enhanced perception of music may induce changes in the cochlea resulting in a better appreciation of music.

Background and Aim: Spatial hearing is a prerequisite for the proper function of the listener in complex auditory environments. In the present study, a Persian version of the dynamic spatial-quick speech in noise (DS-QSIN) has been developed with respect to all possible factors affecting the test and to run five lists for normal hearing subjects and assessment of reliability.
Methods: To construct five new lists according to the original quick speech in noise (QSIN) test, we used frequent, familiar, and difficult words to construct unpredictable sentences. After determining the content and face validity of the sentences, 30 selected sentences were played using a DS-QSIN software for 35 subjects aged 18–25 years. The reliability of the test was assessed after repeating the test after two weeks.
Results: According to expert judges, these 30 sentences showed acceptable content and face validity with the changes. The average signal-to-noise ratio (SNR) loss of five lists was –5.2 dB. No significant difference was seen between men and women in all lists. The results indicate no difference in the average SNR loss between the five lists. Regarding the reliability assessment, the test-retest correlation coefficient was 0.5 to 0.7 (p<0.05). The intra-class correlation coefficient between test-retest was statistically significant (p>0.001) and confirmed that the lists have high reliability and repeatability.
Conclusion: DS-QSIN test showed good validity and reliability and can be helpful in diagnosis and selecting the best method for rehabilitation of people with a spatial hearing disorder.

Background and Aim: The incidence of noise-induced hearing loss (NIHL) is increasing rapidly worldwide. It has been shown that the long-term exposure to noise leads to permanent hearing loss. There is currently no treatment for NIHL and it is mainly managed by preventive measures. This study aimed to develop a training software to improve speech-in-noise (SIN) perception in the elderly suffering from mild-to-moderate NIHL due to temporal fine structure (TFS) damage.
Methods: This is a non-randomized clinical trial conducted on 8 older men aged 60-75 years (Mean age = 68 ± 4.5 years) with mild-to-moderate NIHL at high frequencies (43.75±6.0 dB HL) with at least for five years of work in noisy environment. They received rehabilitation using a researcher-developed training software targeted TFS for five weeks. To assess the efficiency of the training software, the signal-to-noise ratio for 50% correct scores (SNR-50%) was calculated using the word-in-noise test before and after the trial.
Results: The SNR-50% improved significantly in all participants from 13±2.63 dB to 6.10±2.85 dB (p<0.001). In the multiple linear regression model, the rehabilitation by the training software predicted 68% of improvement in SNR-50% (coefficient of determination=0.676).
Conclusion: Rehabilitation by the training software developed based on TFS can improve SIN perception in the elderly with NIHL.

Background and Aim: Stress could play either helpful or harmful roles in vestibular compensation, the process of recovery after vestibular system lesions. Herein, we examined the effect of two stressor types on vestibular compensation: chronic anxiety disorder induced by early maternal separation (MS), and caloric restriction by an intermittent fasting (IF) diet.
Methods: Male Wistar rats (n=56) received maternal separation (the MS group), intermittent fasting (IF group), unilateral vestibular deafferentation (UVD group), or a mixture of these interventions (UVD+IF, UVD+MS, and UVD+IF+MS). All the groups were compared with control animals. The animals’ balance, motor coordination, anxiety, locomotor activity, and serum cortisol levels were evaluated by rotarod, open field, and enzyme-linked immunosorbent assay methods, respectively. The data were compared with those of the healthy control (HC) group.
Results: The UVD animals did not show a significant change in the time on the rod, except for the IF+UVD group (p=0.04). There was no significant difference between the experimental groups on the open field indices, except for the MS+IF+UVD group which traveled a significantly less total distance (p=0.02). Serum cortisol levels were significantly higher than HCs for all the groups except for the sham saline and IF+UVD group (p<0.05).
Conclusion: IF seems to promote compensation after UVD, while MS may disrupt it. However, IF loses its beneficial outcomes if the animal has received another source of stress, i.e. MS.

Background and Aim: Ischemic injury is a major cause of hearing loss and oxidative stress is an important part of ischemic injury. The goal of this study was to evaluate the cochlear oxidative stress effect on auditory responses in male rats.
Methods: Cochlear oxidative stress was induced by bilateral carotid artery occlusion for 20 minutes. The rats were evaluated by biochemical inflammatory factors tumor necrosis factor-α [TNF-α] and C-reactive protein (CRP) in the day before and 1st, 4th, and 7th days following surgery. The auditory brainstem response (ABR) and electrocochleography (ECochG) were evaluated on the day before surgery and 14th, 21th and 28th days after surgery.
Results: TNF-α and CRP levels concentrations increased one day after ischemia and subsequently decreased on the 7th day. The click and tone burst evoked ABR showed increased thresholds on day14th, 21th, and 28th. The highest threshold was recorded on day14th. The ECochG results also were abnormal for 55%, 70%, and 45% of cases on day 14th, 21th, and 28th, respectively.
Conclusion: Cochlear oxidative stress affects hearing sensitivity. The ABR shows elevated thresholds and abnormal ECochG was found in many cases.

Background and Aim: Hearing loss in children leads to speech and language delays, low academic achievement, literacy delays, and psychosocial difficulties. Screening instrument for targeting educational risk (SIFTER) is one of the questionnaires used for evaluation of students’ performance in schools. The current study aims to develop Persian versions of primary and secondary SIFTER questionnaires and assessing their validity and reliability.
Methods: The main English versions of primary and secondary SIFTER questionnaires were translated into Persian named as P-SIFTER and secondary P-SIFTER. Then, their face validities were determined based on the options of related experts. The final versions were completed by 55 teachers of 150 students (64 primary and 86 secondary school students) divided into two groups of hearing-impaired (HI) and normal-hearing (NH) students. The testretest reliabilities were assessed in 117 students (64 primary and 53 secondary school students).
Results: The results revealed that these questionnaires had high face validity. The content validity index for P-SIFTER and secondary P-SIFTER were obtained 0.94 and 0.92, respectively. The total score of P-SIFTER was 51.85 and 65.41 in HI and NH students, respectively. For the secondary P-SIFTER, it was 58.75 and 67.48, respectively. The test-retest reliability showed high correlation for NH and HI students between P-SIFTER and secondary P-SIFTER scores. The Cronbach’s alpha value for the overall score of P-SIFTER was 0.96 for both HI and NH students; for secondary P-SIFTER, the values were 0.94 and 0.93, respectively.
Conclusion: The Persian versions of primary and secondary SIFTER questionnaires have acceptable validity and reliability.

Background and Aim: Many aspects and features of auditory system can be improved by musical training. This study aimed to investigate the effects of a stringed musical instrument playing course on temporal resolution and temporal fine structure (TFS) processing.
Methods: This analytical cross-sectional study was conducted on 44 normal-hearing adults aged 20–40 years divided to two groups. The first group included 22 stringed musical instruments players (13 males) with at least three years of experience, and the second group were 22 non- players (13 males). The random gap detection test (RGDT) was used to measure temporal resolution aspect of hearing. For TFS processing, latest version of temporal fine structure-adaptive frequency (TFS-AF) test was used.
Results: The TFS-AF results showed no statistically significant difference between groups in different interaural phase differences (IPDs). The RGDT results showed significant differences between groups at 500, 1000 and 2000 Hz, but not at 4000 Hz. Spearman correlation test results showed no statistically significant correlation between the results of TFS-AF and RGDT.
Conclusion: Musical training has no effect on TFS processing but considerably enhances gap detection ability. Their underlying mechanisms for TFS processing and gap detection are different.