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Background and Aim: Assessment of central auditory processing skills needs various behavioral tests in format of a test battery. There is a few Persian speech tests for documenting central auditory processing disorders. The purpose of this study was developing a dichotic test formed of one-syllabic words suitable for evaluation of central auditory processing in Persian language children and reporting its preliminary results in a group of normal children.
Materials and Methods: Persian words in competing manner test was developed utilizing most frequent monosyllabic words in children storybooks reported in the previous researches. The test was performed at MCL on forty-five normal children (39 right-handed and 6 left-handed) aged 5-11 years. The children did not show any obvious problem in hearing, speech, language and learning. Free (n=28) and directed listening (n=17) tasks were investigated.
Results: The results show that in directed listening task, there is significant advantage for performance of pre-cued ear relative to opposite side. Right ear advantage is evident in free recall condition. Average performance of the children in directed recall is significantly better than free recall. Average row score of the test increases with the children age.
Conclusion: Persian words in competing manner test as a dichotic test, can show major characteristics of dichotic listening and effect of maturation of central auditory system on it in normal children.

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Background and Aim: The auditory steady state response is a modern test for estimating hearing thresholds, especially in difficult to test individuals . However, there are few bone conduction auditory steady state response data, particularly for individuals with hearing loss. The objective of this study was to investigate bone conduction auditory steady state response thresholds in individuals with sensorineural hearing loss and normal hearing.

Methods: In a cross-sectional study, 10 individuals with normal hearing and 10 with sensorineural hearing loss at the age of 15-30 years were selected by non-probability sampling. Auditory steady state response and pure tone audiometry to bone conduction stimuli in 500 and 2000 Hz were recorded in two groups. Paired and independent t-test were used to compare data between the groups.

Results: There was low correlation between bone conduction auditory steady state response and pure tone audiometry in both groups (p>0.05 for both). The difference of behavioral thresholds and auditory steady state response in 500 Hz was higher than 2000 Hz in both groups (p=0.033 for normal hearing and p=0.017 for sensorineural hearing loss groups). Comparison of these results showed significant differences between the two groups (p<0.001).

Conclusion: In both groups, there was low correlation between bone conduction auditory steady state response and pure tone audiometry thresholds. In individuals with sensorineural hearing loss and in higher frequencies , bone conduction auditory steady state response thresholds was closer to pure tone audiometery thresholds.

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Background and Aim: It is not known how electrocochleography components of action potentials (AP) and summating potentials (SP) are changed in response to CE-chirp stimulus using extra-tympanic electrodes. This study was done for comparing summating potentials and action potentials specifications in response to CE-chirp and click stimuli.

Methods: Electrocochleography components of action potentials and summating potentials were recorded in 16 normal hearing subjects (8 men and 8 women) aged 22-30 years (mean: 26.7 with SD 2.5 years) with audiometric (250-8000 Hz) hearing thresholds of 15 dB HL or better in response to click and CE-chirp stimulus at 90 dB nHL. Amplitude, duration, latency and area of summating potentials and action potentials and SP/AP amplitude and area ratios were compared.

Results: Among the measured parameters, action potentials amplitude in response to CE-chirp stimulus (0.41 with SD 0.26 µV ) was significantly smaller than action potentials amplitude in response to click (0.61 with SD 0.29 µV ) stimulus (p<0.005). Relative frequency of detecting summating potentials in response to CE-chirp (68.7%) was lower than (100%) click (p<0.005).

Conclusion: Recording electrocochleography component of summating potentials and action potentials with CE-chirp stimulus at high intensity level in normal hearing individuals shows no advantage over click stimulus. Small amplitude of summating potentials as a major problem of extra-tympanic electrocochleography cannot be solved using CE-chirp stimulus.

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Background and Aim: CE-Chirp stimulus has been developed for stimulating more apical regions of the cochlea. Inadequacy of clinical information on the latency and amplitude characteristics of ABR evoked by CE-chirp at different levels in addition to discrepancy in identifying earlier ABR waveforms using CE-chirp stimulus are the reasons of this study.

Methods: This study was done by recoding ABR to click and broad-band CE-chirp stimuli in the right ear of 15 non-randomly selected normal-hearing individuals with age range of 20-30 years old. Frequency of recordable waves I and III, as well as threshold, amplitude, and latency of wave V were compared in response to click and CE-Chirp at 20-80 dB nHL.

Results: At 80 dB nHL, click stimulus evokes waves I and III more frequently than chirp stimulus (p=0.012 and p=0.016 respectively). At 20 and 40 dB nHL, wave V latency evoked by CE-Chirp is significantly longer than wave V latency evoked by click (p=0.012 and p=0.0001 respectively) however, at 80 dB nHL wave V latency evoked by CE-Chirp is shorter than click (p=0.0001). Wave V amplitude for CE-Chirp is significantly larger than for click at levels of 20, 40 and 60 dB nHL (p=0.0001, p=0.0001 and p=0.013 respectively). Wave V threshold is approximately 5 dB lower with CE-chirp compared to click (p=0.014).

Conclusion: Except at high levels, CE-Chirp evokes wave V with larger amplitude and lower threshold than click. Possibility of recording earlier ABR waves is reduced with CE-chirp stimulus.

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Background and Aims: The dichotic listening subtest is considered as an important component of the test battery for auditory processing assessment in both children and adults. A randomized dichotic digits test (RDDT) was created to compensate for sensitivity weakness of double digits when detecting abnormal ear asymmetry during dichotic listening. The aim of this study was the development and initial evaluation of the Persian randomized dichotic digits test.

Method: Persian digits 1-10 (except for the bisyllabic digit, 4) uttered by a native Persian language speaker were recorded in a studio. After alignment of intensity and temporal characteristics of digit waveforms, lists 1 and 2 of the RDDT were reproduced. List 1 of the test was administered at 55 dBHL on 50 right-handed normal hearing individuals (with an equal sex ratio) in the age group of 18-25 years and hearing thresholds of 15 dBHL or better in audiometric frequencies.

Results: Mean (standard deviation) percent-correct score for right and left ears and right ear advantage of the subjects was 94.3 (5.3), 84.8 (7.7), and 9.5 (7.0) percent, respectively. Sixty percent of the subjects showed normal results and unilateral and bilateral deficits were seen in 24 percent and 16 percent, respectively.

Conclusion: It seems the Persian version of RDDT is the same as the original test as it is able to test ear asymmetry , unilateral and bilateral deficits in dichotic listening.