The Acceptable Noise Level Benefit From Directionality for Listeners With Severe Hearing Loss

OBJECTIVES: Directional microphone technology can enhance the speech intelligibility and listening comfort of listeners with hearing impairment. The main aim of this study is to investigate and compare the benefit derived by listeners with severe hearing loss from directional microphone technology with that derived by listeners with moderate hearing loss. METHODS: The acceptable noise levels (ANLs) of two groups of listeners with moderate or severe hearing impairment (17 subjects in each group) were measured under unaided, omnidirectional-baseline-aided, and directional-aided conditions. RESULTS: Although the absolute ANL of the listeners in the severe hearing loss group was significantly higher than that of the listeners in the moderate hearing loss group, their derived benefit was equivalent to that derived by the listeners in the moderate hearing loss group. ANL and hearing loss degree were significantly related. Specifically, the ANL increased with the severity of hearing loss. CONCLUSION: Directional microphone technology can provide the benefits of listening comfort to listeners with severe hearing loss.

[Developing and evaluating validity and reliability of Persian version of [dichotic fused rhymed word test]]

Objective: The aim of the present study is to develope and evaluate validity and reliability of Persian version of Dichotic Fused Rhymed Words Test in 18-25 years old normal population

Materials and Methods: The Persian version of Dichotic Fused Rhymed Words Test consisted of 15 pairs of monosyllable rhymed words. These paired words are set in 4 lists of 30 items that simultaneously were presented one to the left and another to the right ear so that they lead to perception of a single fusion concept. After selecting the test material from Moin Persian dictionary according to the intended criteria and pairing the rhymed words, content validity was assessed through lawshe method by 10 expert persons, words with high validity were selected and lists were set. Then, the words of each list were recorded on CD in a dichotic mode. Thereafter, the study was performed in 124 normal individuals [68 females and 56 males] within ages ranging from 18 to 25 years and the scores were recorded on a designed scoring form. To examine reliability of test, the test was performed on 15 individuals again two weeks after the initial test and the Pearson correlation was assessed

Results: There are significant differences between mean scores of right and left ears [P<0.001]. Content Validity Ratio was 0.8-1 for every item. Pearson correlation was 0.83 for test-retest [P<0.001]. Cronbach's alpha and Intra Class Correlation [ICC] was 0.81 and 0.84 for internal correlation between scores of lists of test. The result showed that there is significant correlation between the lists

Conclusion: Based on the obtained results, the Persian version of Dichotic Fused Rhymed Words Test has a good content validity and reliability. It can be used in detecting function of corpus callosum, lateralization of the cerebral hemispheres and assessment of central auditory processing