Effect of a Dichotic Interaural Time Difference Program on Dichotic Listening Deficit of Children with Learning Difficulty.

BACKGROUND: Dichotic listening deficit (DLD) is a common sign in children showing learning problem and is identified during auditory processing assessment. A dichotic listening training program was developed in which the weak ear lags behind the strong ear in time and has certain practices for switching attention between the ears and auditory memory. PURPOSE: The aim of the present study was to evaluate the effectiveness of this treatment program on dichotic performance of primary school children showing DLD. RESEARCH DESIGN: A pre/post clinical trial without control study. STUDY SAMPLE: Twenty-five primary school children, aged 7 to 12 years (mean = 9.3 years), showing DLD. DATA COLLECTION AND ANALYSIS: Several primary schools referred the children with learning difficulty to us. We defined learning difficulty as a score of 2 and lower on a five-point scale in at least two primary school courses in the current semester. The children with DLD participated in listening practices three times a week for 10 weeks, each session lasting for 30 minutes. The practices started with one pair of dichotic digits and ended in practice with sentences. The weak ear lag varied from 100 to 1,000 milliseconds. In the last stage of the practices, the precued and postcued directed response aimed at strengthening auditory memory and switching attention between the ears. The results obtained by the tests of dichotic digits, competing words, and competing sentences before and after the intervention were compared using paired t-test. Hedges's g was calculated as the effect size. RESULTS: Comparison of the results of pretraining and those of posttraining revealed that the average dominant ear (DE) and nondominant ear (NDE) scores in dichotic listening tests improved significantly with medium-to-large effect sizes. It was also found that the mean change in the NDE score of the children was significantly greater than that of the DE score for all the tests. CONCLUSIONS: Dichotic interaural time difference training that employed dichotic lag phenomenon followed by directed response practices significantly improved the DE and the NDE scores of the schoolchildren with DLD.

Auditory Recognition of Digit-in-Noise under Unaided and Aided Conditions in Moderate and Severe Sensorineural Hearing Loss.

BACKGROUND AND OBJECTIVES: The speech-in-noise test is typically performed using an audiometer. The results of the digit-in-noise recognition (DIN) test may be influenced by the flat frequency response of free-field audiometry and frequency of the hearing aid fit based on fitting rationale. This study aims to investigate the DIN test in unaided and aided conditions. SUBJECTS AND METHODS: Thirty four adults with moderate and severe sensorineural hearing loss (SNHL) participated in the study. The signal-to-noise ratio (SNR) for 50% of the DIN test was obtained in the following two conditions: 1) the unaided condition, performed using an audiometer in a free field; and 2) aided condition, performed using a hearing aid with an unvented individual earmold that was fitted based on NAL-NL2. RESULTS: There was a statistically significant elevation in the mean SNR for the severe SNHL group in both test conditions when compared with that of the moderate SNHL group. In both groups, the SNR for the aided condition was significantly lower than that of the unaided condition. CONCLUSIONS: Speech recognition in hearing-impaired patients can be realized by fitting hearing aids based on evidence-based fitting rationale rather than by measuring it using free-field audiometry measurement that is utilized in a routine clinic setup.

The Effects of Hearing Aid Digital Noise Reduction and Directionality on Acceptable Noise Level.

OBJECTIVES: Two main digital signal processing technologies inside the modern hearing aid to provide the best conditions for hearing aid users are directionality (DIR) and digital noise reduction (DNR) algorithms. There are various possible settings for these algorithms. The present study evaluates the effects of various DIR and DNR conditions (both separately and in combination) on listening comfort among hearing aid users. METHODS: In 18 participants who received hearing aid fitting services from the Rehabilitation School of Shahid Beheshti University of Medical Sciences regularly, we applied acceptable noise level (ANL) as our subjective measure of listening comfort. We evaluated both of these under six different hearing aid conditions: omnidirectional-baseline, omnidirectional-broadband DNR, omnidirectional-multichannel DNR, directional, directional-broadband DNR, and directional-multichannel DNR. RESULTS: The ANL results ranged from -3 dB to 14 dB in all conditions. The results show, among all conditions, both the omnidirectional-baseline condition and the omnidirectional-broadband DNR condition are the worst conditions for listening in noise. The DIR always reduces the amount of noise that patients received during testing. The DNR algorithm does not improve listening in noise significantly when compared with the DIR algorithms. Although both DNR and DIR algorithms yielded a lower ANL, the DIR algorithm was more effective than the DNR. CONCLUSION: The DIR and DNR technologies provide listening comfort in the presence of noise. Thus, user benefit depends on how the digital signal processing settings inside the hearing aid are adjusted.

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.

Test-Retest Reliability and Minimal Detectable Change of Randomized Dichotic Digits in Learning-Disabled Children: Implications for Dichotic Listening Training.

BACKGROUND: Evaluation of dichotic listening to digits is a common part of many studies for diagnosis and managing auditory processing disorders in children. Previous researchers have verified test-retest relative reliability of dichotic digits results in normal children and adults. However, detecting intervention-related changes in the ear scores after dichotic listening training requires information regarding trial-to-trial typical variation of individual ear scores that is estimated using indices of absolute reliability. Previous studies have not addressed absolute reliability of dichotic listening results. PURPOSE: To compare the results of the Persian randomized dichotic digits test (PRDDT) and its relative and absolute indices of reliability between typical achieving (TA) and learning-disabled (LD) children. RESEARCH DESIGN: A repeated measures observational study. STUDY SAMPLE: Fifteen LD children were recruited from a previously performed study with age range of 7-12 yr. The control group consisted of 15 TA schoolchildren with age range of 8-11 yr. DATA COLLECTION AND ANALYSIS: The Persian randomized dichotic digits test was administered on the children under free recall condition in two test sessions 7-12 days apart. We compared the average of the ear scores and ear advantage between TA and LD children. Relative indices of reliability included Pearson's correlation and intraclass correlation (ICC2,1) coefficients and absolute reliability was evaluated by calculation of standard error of measurement (SEM) and minimal detectable change (MDC) using the raw ear scores. RESULTS: The Pearson correlation coefficient indicated that in both groups of children the ear scores of test and retest sessions were strongly and positively (greater than +0.8) correlated. The ear scores showed excellent ICC coefficient of consistency (0.78-0.82) and fair to excellent ICC coefficient of absolute agreement (0.62-0.74) in TA children and excellent ICC coefficients of consistency and absolute agreement in LD children (0.76-0.87). SEM and SEM% of the ear scores in TA children were 1.46 and 1.44% for the right ear and 4.68 and 5.47% for the left ear. SEM and SEM% of the ear scores in LD children were 4.55 and 5.88% for the right ear to 7.56 and 12.81% for the left ear. MDC and MDC% of the ear scores in TA children varied from 4.03 and 3.99% for the right ear to 12.93 and 15.13% for the left ear. MDC and MDC% of the ear scores in LD children varied from 12.57 and 16.25% for the right ear to 20.89 and 35.39% for the left ear. CONCLUSIONS: The LD children indicated test-retest relative reliability as high as TA children in the ear scores measured by PRDDT. However, within-subject variations of the ear scores calculated by indices of absolute reliability were considerably higher in LD children versus TA children. The results of the current study could have implications for detecting real training-related changes in the ear scores.

Educational level and pseudohypacusis in medico-legal compensation claims: a retrospective study.

Pseudohypacusis or the intentional feigning of hearing loss is a challenging situation in the medicolegal evaluation of hearing levels. Few studies have been performed on predisposing factors that make compensation claims susceptible to malingering. The goal of this study was to investigate the relationship between educational level and frequency of pseudohypacusis in a group of medico-legal clients. Retrospectively, we studied the files of subjects (n=421) referred to the audiology clinic of a government hospital during a 12 month period. Educational levels of the individuals with and without pseudohypacusis were compared by the Chi-square test. The results show that individuals with pseudohypacusis have lower educational levels than cooperative clients. The relative frequency of individuals with pseudohypacusis among illiterates (43.5%) was clearly higher than individuals with higher educational levels (17.5%). The education level of a person filing a compensation claim may alert an examiner in detecting pseudohypacusis.