Ear Advantage Research Articles

Dichotic word recognition across ages

Successful auditory word recognition depends upon acquiring lexical and phonological representations during language acquisition. The intake of information through the auditory system requires an online integration of differing and potentially competing information presented to the two ears. The goal of the present study was to collect developmental data on the auditory-phonetic processing of words in a dichotic listening task with the participation of 320 Hungarian-speaking children between the ages of 3 and 10. Dichotic listening techniques have been used as a sensitive non-invasive procedure to assess language lateralization. Data were scored for each participant as the percentage (and number) of correctly recalled words for the right and left ear input. Results showed a significant increase of the correctly repeated words across ages. As expected, more correctly recalled words were found heard in the children’s right ear than in their left ear as an effect of right ear advantage. The dichotic listening method seems to be a good way to detect the auditory-phonetic abilities of typically developing children.

Evidence of a Right Ear Advantage in the absence of auditory targets

The Right Ear Advantage effect (REA) was explored in a white noise speech illusion paradigm: binaural white noise (WN) could be presented i) in isolation (WN condition), ii) overlapped to a voice pronouncing the vowel /a/ presented in the left ear (LE condition), iii) overlapped to a voice pronouncing the vowel /a/ presented in the right ear (RE condition). Participants were asked to report in which ear the voice has been perceived. The voice could be female or male, and it could be presented at 4 different intensities. Participants carried out the task correctly both in LE and in RE conditions. Importantly, in the WN condition the “right ear” responses were more frequent with respect to both the chance level and the “left ear” responses. A perceptual REA was confirmed both in LE and RE conditions. Moreover, when the voice was presented at low intensities (masked by WN), it was more frequently reported in the right than in the left ear (“illusory” REA). A positive correlation emerged between perceptual and illusory REA. Potential links of the REA effects with auditory hallucinations are discussed.

Impact of Consistency in Daily Device Use on Speech Perception Abilities in Children with Cochlear Implants: Datalogging Evidence.

Cochlear implants (CIs) give children with severe to profound hearing loss access to sound. There appears to be a dose effect of sound exposure on speech perception abilities as shown by the positive influence of early implantation and CI experience. The consistency in device use per day could also affect sound dose, potentially affecting perceptual abilities in children with CIs. The objectives of the present study were to identify the impact of consistency in device use on: (1) speech perception abilities and (2) asymmetry in speech perception abilities between bilateral CIs. Retrospective analysis. To achieve the first objective, data from 65 children (age range at speech test: 1.91-18.05 yrs) with one (unilaterally implanted or bimodal) or two CIs (sequentially or simultaneously implanted) were included. A subset of data from 40 children with bilateral CIs was included to achieve the second objective. Of the 40 children with two CIs, 15 received their CIs sequentially. Device use information was extracted from datalogs stored in personal speech processors using custom software. Speech perception scores per CI collected in quiet were also evaluated. Multiple regression was used to assess the impact of daily CI use, while controlling for factors previously identified to affect speech perception: age at speech test, length of pre-CI (acoustic) hearing experience, length of CI hearing experience, and order of CI for the first objective, and CI category (simultaneous/sequential implantation), interimplant delay, and length of CI experience for the second objective. On average, children wore their CIs for 11.59 ± 2.86 hours/day and, with one CI, exhibited 65.07 ± 22.64% accuracy on speech perception tests. Higher monaural speech perception scores were associated with longer everyday CI use and CI experience (p < 0.05). Among children with bilateral CIs, those with simultaneously implanted CIs and similar bilateral hearing experience demonstrated a small but significant right ear advantage with higher speech perception scores when using the right rather than left CI (mean difference = 4.55 ± 9.83%). The asymmetry in speech perception between CIs was larger and more variable in children who received their CIs sequentially (mean difference CI1-CI2 = 27.48 ± 24.87%). These asymmetries decreased with longer/consistent everyday use of the newer CI (p < 0.05). Yet, despite consistent everyday device use of the second CI (>12 hours/day), only a small proportion of children implanted sequentially (one out of seven children) achieved symmetrical function similar to children with simultaneously received bilateral CIs. Consistent everyday CI use contributes to higher speech perception scores. Although consistent CI use can help reduce the asymmetry in speech perception abilities of children with sequentially implanted CIs subsequent to interimplant delay, residual asymmetry often persists.

No Squelch Effect After Sequential Bilateral Cochlear Implantation in Postlingually Deafened Adults: Is There a First Ear Advantage?

To investigate whether a squelch effect develops in postlingually deafened adults after sequential bilateral cochlear implantation. Prospective study as part of a randomized controlled trial on the difference between simultaneous versus sequential bilateral cochlear implantation. Tertiary referral center. Sixteen postlingually deafened adults. Sequential bilateral cochlear implantation with a 2-year interimplant interval. A squelch effect was defined as a better bilateral score than unilateral score on a speech-intelligibility-in-noise test with spatially separated sources. The squelch effect was evaluated for the participants' best performing cochlear implant (CI) ear, the left CI in the condition with speech from -60 degrees azimuth and noise from +60 degrees azimuth (S-60 N+60), the right CI (N-60 S+60), CI1 and CI2. Evaluations took place 1, 2 and median 4 years after sequential implantation. No significant squelch effect was found, except for the right CI (N-60 S+60) after 2 years. No differences in speech perception-in-noise from straight ahead were seen between CI1 and CI2. Comparing performance of participants whose better or worse ear was implanted first did not reveal differences either. For the best performing situation, 7/16, 6/16, and 3/12 participants exhibited a squelch effect after 1, 2, and 4 years of follow-up. Participants who underwent sequential bilateral cochlear implantation with a 2-year interimplant interval did not develop an evident squelch effect on group level after a median follow-up of 4 years. Individual participants were able to make use of the squelch effect. The less evident squelch effect is at odds with our group of simultaneously implanted bilateral cochlear implant users. Neither a difference between CI1 and CI2, nor implanting the better or worse ear first could explain the less evident squelch effect in these patients. Dutch Trial Register NTR1722.

A Nonsense Consonant-Vowel-Consonant Word Test to Assess Auditory Processing.

Dichotic listening (DL), or how the two ears work together as a team, is often used in the assessment of auditory processing disorders in both children and adults. Currently, the battery of dichotic tests includes stimuli containing words, digits, and nonsense consonant-vowel syllables. Single-syllable nonsense words are of particular use in assessing processing abilities because they can evaluate auditory processing without a listener's dependence on linguistic knowledge. Therefore, nonsense words may assess auditory processes independently of previous vocabulary knowledge. This study is designed to assess the clinical applicability and face validity of a nonsense word DL test in a young adult population. This study included an experimental design to investigate the performance of young adult listeners on a Dichotic Nonsense Word (DNW) test spoken by a male and female speaker. The results were compared with one study that investigated young adult listener's performance on dichotic tests of English words. A total of 100 young adult participants were recruited from the School of Health and Rehabilitation Sciences at the University of Pittsburgh to participate in the study. The participants ranged in age from 20 to 30, with an average age of 23, and all participants had normal hearing. DL performance was measured in all participants using the Dichotic Words Test (DWT) and the newly developed DNW test. Kolmogorov-Smirnoff tests of normality were used to assess distribution of right- and left-ear scores. Criterion cutoff scores were determined for the percent correct scores in the nondominant ear and dominant ear and for ear advantage. Scores were significantly different between the two tests in the right ear, Z = -8.258, p < 0.001, and in the left ear, Z = -8.471, p < 0.001. Scores within each test were higher for the right ear than for the left ear, and scores for both ears were significantly lower on the DNW test than for the DWT. Ear advantage scores from the DNW test were significantly larger than those obtained from the DWT. The low and high 95% criterion cutoff ranges for the DNW test were considerably wider than the 95% criterion cutoff ranges for the DWT. Results indicate that the new DNW test may be a useful clinical tool within a test battery for evaluating auditory processing skills independent of vocabulary knowledge.

Auditory processing and neuropsychological profiles of children with functional hearing loss

ObjectivesThis paper compares structured history, auditory processing abilities and neuropsychological findings of children with functional hearing loss (FHL) to those with suspected auditory processing disorder without FHL (control). The main aim was to evaluate the value of a holistic assessment protocol for FHL used in a routine pediatric audiology clinic. The protocol incorporated a commercially available test battery for auditory processing disorder (APD), non-verbal intelligence (NVIQ) and tools to screen for common co-existing neurodevelopmental conditions such as attention deficit hyperactivity disorder (ADHD), language impairment (LI) and developmental coordination disorder (DCD). The outcome of such holistic assessment was expected to help in understanding the nature of FHL and to provide individualized support to mitigate their difficulties. MethodsThis retrospective study compared two groups, 40 children (M = 17, F = 23) in each group between seven and sixteen years of age, one group with a history of FHL and the other with suspected APD without FHL (control). The groups were matched against age, gender, hand use, diagnosis of APD or non-APD (31 with APD and 9 without APD in each group) and non-verbal intelligence. All the children were healthy English speaking children attending mainstream schools with no middle or inner ear abnormalities. Structured history was obtained from parents regarding different nonacademic and academic concerns. The SCAN-3:C and SCAN-3:A test batteries were used to assess auditory processing abilities; Lucid Ability test for NVIQ; Children's Communication Checklist-2 (CCC-2) for language ability; Swanson Nolan and Pelham-IV Rating Scale (SNAP-IV) for ADHD; and the manual dexterity components of the Movement Assessment Battery for Children-2 (MABC-2) as a screening tool for DCD. ResultsAbout 60% of children in both the groups had concerns regarding listening in noisy background. In the history, poor attention was reported in 45% of children in the FHL group compared to 82.5% in the control group (p < 0.01). Hyperacusis was present in 35% of children in the FHL group and in 62% of children in the control group (p < 0.05). Concerns about overall academic abilities were present in 59% of children in the FHL group and 75% of the controls (p > 0.05). Only 15% of children in the FHL group had concerns with numeracy skills in contrast to 41% of the controls (p < 0.05). Significantly fewer (p < 0.01) children in the FHL group (41%) received additional support at school than the controls (75%). Fewer children performed poorly in Filtered Words (FW) test of the SCAN-3 batteries, 30% in the FHL group and 17.5% in the control group, in contrast to Auditory Figure Ground 0 (AFG0), 85% in FHL and 80% in the control group. The number of children performing poorly in AFG0 was significantly higher compared to all the other SCAN-3 tests in FHL (P < 0.05), in contrast to FW and Competing Sentences (CS) only in the control group (p < 0.05). The control group had higher prevalence of atypical ear advantage (AEA) in left directed Competing Words (CW) (32.5%) and Time Compressed Sentences (TCS) (32.5%) compared to FW (7.5%). In contrast, FHL group had higher prevalence of AEA in AFG0 (48.7%) compared to CS (21%). High proportions of children in both the groups had LI (80% in FHL and 82.5% in the control group), with significantly lower (p < 0.05) levels of ADHD symptoms in the FHL group (39.5%) compared to the control group (72.5%). Impaired manual dexterity was present in 30.7% of children in FHL group and 47.5% in the controls. ConclusionsThe prevalences of APD and language impairment are high compared to ADHD symptoms in children with FHL, and holistic assessment is recommended. Despite some similarities in the auditory and neuropsychological profiles between children with FHL and those with suspected APD without FHL some differences were noted. The results suggest that children with FHL have genuine difficulties that need to be identified and addressed. Future research is required to identify the neural pathways which could explain the similarities and dissimilarities between the two groups.

Audiological Profile in Children with Autism Spectrum Disorders

Background: Autism spectrum disorder is defined by the Diagnostic Statistical Manual of Mental Disorders V (DSM V) as a neurobehavioral disorder manifested by persistent deficits in social and communication interaction, deficits in developing, understanding and maintaining relationships, as well as abnormal and fixed interests and repetitive behavior. Symptoms must be present at early childhood and interfere with daily function. The majority of individuals with ASD demonstrate some degree of auditory dysfunction. The level and expression of this dysfunction ranges from deafness and increased thresholds to hyperacusis and difficulty listening with background noise. Objective: The purpose of this study was to characterize the findings of audiological and electrophysiological hearing assessment in individuals with autism and to compare these findings to those obtained in typically developing individuals. Subjects, Materials & Method: Forty one Autistic children are divided into two groups:- group (1) Mild to moderate autism were seventeen children & group (2) Severe autism were twenty four children) were enrolled in this study (Whose ages were 2-6.5 years old) compared with ten typically developing matching peers. All Autistic children in the study had a definite medical diagnosis of Autism according to DSM-5 and based on the severity of symptomatology, ASD children were assessed and divided using CARS score (Childhood autism rating scale). Audiologic evaluation consisted of a case history, otoscopic examinatioin, behavioral free field evaluation, acoustic immittance measures (Tympanogram and Acoustic reflexes), speech audiometry, measurement of distortion product otoacoustic emissions and auditory brain stem response. Results: Our results support an association between ASD and higher DPOAEs S/N ratios at only 500 & 750 Hz. Moreover, ABR in ASD children showed a significant increase in waves III & V absolute latencies and I- III & I-V inert peak latencies (In both groups of ASD), with inter aural asymmetry as shortened right ear III-V & I-V inter peak latencies reflecting a more right ear advantage (mild to moderate group), in addition to a significant decrease in waves V/I amplitude ratio (Both ASD groups). Conclusion: The OAE responses of children with ASD were highly significantly only at 500 Hz (Both groups) 750 Hz (Mild to moderate group). ASD children (either mild to moderate or severe) had a significant increase in ABR waves III & V peak absolute latencies and I-III & I-V inter peak latencies. Asymmetrical ABR findings also noted in children with ASD (mild to moderate group) as shortened right ear III-V & I-V inter peak latencies (more prominent right ear advantage). In ABR also the amplitude of peak I in response to 90 dB nHL click stimulation was greater than the amplitude of peak V significantly in both groups of ASD children than controls.

Dichotic training in children with auditory processing disorder

ObjectivesSeveral test batteries have been suggested for auditory processing disorder (APD) diagnosis. One of the important tests is dichotic listening tests. Significant ear asymmetry (usually right ear advantage) can be indicative of (APD). Two main trainings have been suggested for dichotic listening disorders: Differential Interaural Intensity Difference (DIID) and Dichotic Offset Training (DOT). The aim of the present study was comparing the efficacy of these two trainings in resolving dichotic listening disorders. Methods12 children in the age range of 8 to 9 years old with APD were included (mean age 8.41 years old±0.51). They all had abnormal right ear advantage based on established age-appropriate norms for Farsi dichotic digit test. Then subjects were randomly divided into two groups (each contained 6 subjects): group 1 received DIID training (8.33 years old ±0.51) and group 2 received DOT training (8.50 years old±0.54). ResultsBoth trainings were effective in improvement of dichotic listening. There was a significant difference between two trainings with respect to the length of treatment (P-value≤0.001). DOT needed more training sessions (12.83±0.98 sessions) than DIID (21.16±0.75 sessions) to achieve the same amount of performance improvement. ConclusionBased on the present study it can be assumed that DOT might be a good replacement for DIID training in cases that DIID is not applicable and DIID candidacy conditions are not met. To generalize the results, studies with larger sample sizes are recommended.

Referral and Diagnosis of Developmental Auditory Processing Disorder in a Large, United States Hospital-Based Audiology Service.

Children referred to audiology services with otherwise unexplained academic, listening, attention, language, or other difficulties are often found to be audiometrically normal. Some of these children receive further evaluation for auditory processing disorder (APD), a controversial construct that assumes neural processing problems within the central auditory nervous system. This study focuses on the evaluation of APD and how it relates to diagnosis in one large pediatric audiology facility. To analyze electronic records of children receiving a central auditory processing evaluation (CAPE) at Cincinnati Children's Hospital, with a broad goal of understanding current practice in APD diagnosis and the test information which impacts that practice. A descriptive, cross-sectional analysis of APD test outcomes in relation to final audiologist diagnosis for 1,113 children aged 5-19 yr receiving a CAPE between 2009 and 2014. Children had a generally high level of performance on the tests used, resulting in marked ceiling effects on about half the tests. Audiologists developed the diagnostic category "Weakness" because of the large number of referred children who clearly had problems, but who did not fulfill the AAA/ASHA criteria for diagnosis of a "Disorder." A "right-ear advantage" was found in all tests for which each ear was tested, irrespective of whether the tests were delivered monaurally or dichotically. However, neither the side nor size of the ear advantage predicted the ultimate diagnosis well. Cooccurrence of CAPE with other learning problems was nearly universal, but neither the number nor the pattern of cooccurring problems was a predictor of APD diagnosis. The diagnostic patterns of individual audiologists were quite consistent. The number of annual assessments decreased dramatically during the study period. A simple diagnosis of APD based on current guidelines is neither realistic, given the current tests used, nor appropriate, as judged by the audiologists providing the service. Methods used to test for APD must recognize that any form of hearing assessment probes both sensory and cognitive processing. Testing must embrace modern methods, including digital test delivery, adaptive testing, referral to normative data, appropriate testing for young children, validated screening questionnaires, and relevant objective (physiological) methods, as appropriate. Audiologists need to collaborate with other specialists to understand more fully the behaviors displayed by children presenting with listening difficulties. To achieve progress, it is essential for clinicians and researchers to work together. As new understanding and methods become available, it will be necessary to sort out together what works and what doesn't work in the clinic, both from a theoretical and a practical perspective.

Level dominance effect and selective attention in a dichotic sample discrimination task.

Differences in individual listening patterns are reported for a dichotic sample discrimination task. Seven tones were drawn from normal distributions with means of 1000 or 1100 Hz on each trial. Even-numbered tones (2, 4, and 6) and odd-numbered tones (1, 3, 5, and 7) were drawn, respectively, from distributions with a 50-Hz and 200-Hz standard deviation. Task difficulty was manipulated by presenting odd and even tones at different intensities. In easy conditions, high and low informative tones were presented at 70 dB and 50 dB, respectively. In difficult conditions, high informative and low informative tones were presented at 50 dB and 70 dB, respectively. Participants judged whether the sample was from high- or low-mean distribution. Decision weights, efficiency, and sensitivity showed a range of abilities to attend to high informative tones, with d' from 2.4-0.7. Most listeners showed a left-ear advantage, while no listeners showed a right ear advantage. Some listeners, but not all, showed no loudness dominance effect with the ability to selectively attend to quiet tones in difficult conditions. These findings show that the influence of an attentional strategy in dichotic listening can overcome the loudness dominance effect for some listeners.

Right Ear Advantage of Speech Audiometry in Single-sided Deafness.

Background:Postlingual single-sided deafness (SSD) is defined as normal hearing in one ear and severely impaired hearing in the other ear. A right ear advantage and dominance of the left hemisphere are well established findings in individuals with normal hearing and speech processing. Therefore, it seems plausible that a right ear advantage would exist in patients with SSD.Methods:The audiometric database was searched to identify patients with SSD. Results from the German monosyllabic Freiburg word test and four-syllabic number test in quiet were evaluated. Results of right-sided SSD were compared with left-sided SSD. Statistical calculations were done with the Mann–Whitney U test.Results:Four hundred and six patients with SSD were identified, 182 with right-sided and 224 with left-sided SSD. The two groups had similar pure-tone thresholds without significant differences. All test parameters of speech audiometry had better values for right ears (SSD left) when compared with left ears (SSD right). Statistically significant results (p < 0.05) were found for a weighted score (social index, 98.2 ± 4% right and 97.5 ± 4.7% left, p < 0.026), for word understanding at 60 dB SPL (95.2 ± 8.7% right and 93.9 ± 9.1% left, p < 0.035), and for the level at which 100% understanding was reached (61.5 ± 10.1 dB SPL right and 63.8 ± 11.1 dB SPL left, p < 0.022) on a performance-level function.Conclusion:A right ear advantage of speech audiometry was found in patients with SSD in this retrospective study of audiometric test results.

Modulation of the dichotic right ear advantage during bilateral but not unilateral transcranial random noise stimulation

Transcranial electrical stimulation (tES) has been increasingly adopted to modulate perceptual and cognitive functions, but the effects on auditory perception are still relatively uncharted. Starting from the evidence that a stronger right ear advantage effect (REA) in dichotic listening positively correlates with speech sound processing, the present study was aimed at modulating the REA by means of high-frequency transcranial Random Noise Stimulation (hf-tRNS). Stimulation was applied over the auditory cortex (AC) either unilaterally (Experiment 1, N = 50) or bilaterally (Experiment 2, N = 24) during a verbal dichotic listening task. The results confirmed the REA both during the sham and the tRNS session in both Experiments. Importantly, a significant enhancement of the REA was found during bilateral hf-tRNS with respect to sham (Experiment 1). No modulation was found when hf-tRNS was applied over the left or right AC with the reference electrode placed on the contralateral shoulder, with respect to sham (Experiment 2). This finding is discussed in the light of previous stimulation studies facing the modulation of hemispheric asymmetries. Our results suggest that the effectiveness of bilateral hf-tRNS in modulating basic speech processing mechanisms could be exploited in the treatment of language impairments.

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

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. 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. A repeated measures observational study. 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. 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. 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. 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.

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Patient-Centered Counseling for Older Adults

The effect of unimodal affective priming on dichotic emotion recognition

ABSTRACTThe present report concerns two experiments extending to unimodal priming the cross-modal priming effects observed with auditory emotions by Harding and Voyer [(2016). Laterality effects in cross-modal affective priming. Laterality: Asymmetries of Body, Brain and Cognition, 21, 585–605]. Experiment 1 used binaural targets to establish the presence of the priming effect and Experiment 2 used dichotically presented targets to examine auditory asymmetries. In Experiment 1, 82 university students completed a task in which binaural targets consisting of one of 4 English words inflected in one of 4 emotional tones were preceded by binaural primes consisting of one of 4 Mandarin words pronounced in the same (congruent) or different (incongruent) emotional tones. Trials where the prime emotion was congruent with the target emotion showed faster responses and higher accuracy in identifying the target emotion. In Experiment 2, 60 undergraduate students participated and the target was presented dichotically instead of binaurally. Primes congruent with the left ear produced a large left ear advantage, whereas right congruent primes produced a right ear advantage. These results indicate that unimodal priming produces stronger effects than those observed under cross-modal priming. The findings suggest that priming should likely be considered a strong top-down influence on laterality effects.

Central conduction time in auditory brainstem response and ear advantage in dichotic listening across menstrual cycle.

The ovarian hormones fluctuate during the menstrual cycle in women. Such fluctuation of sex hormones, in particular estrogen, is believed to affect the central conduction time in auditory function as well as the language lateralization in cognitive function. However, findings are inconsistent. The underlying mechanisms are also unclear. This paper examined if there was any relation between the central conduction time and the language lateralization at different times during the menstrual cycle. Twenty young women with normal menstrual cycle were tested four times (5 to 7 days apart) across the menstrual cycle. The test battery included the electrophysiological measurement of auditory evoked response in brainstem and the speech performance in dichotic listening with monosyllables as stimulus pairs. The dichotic listening task was conducted under the non-forced, forced-right and forced-left attention. The central conduction time was defined by the time elapsed between two auditory elicited responses along the auditory pathway. The language lateralization in dichotic listening was expressed in ear advantage, which was the right-ear score minus the left-ear score. The results showed that the effects of test time were significant on both the central conduction time and the ear advantage under the forced-left attention. Overall, the interaural difference in the central conduction time correlates with the ear advantage (non-forced attention) at the beginning of the menstrual cycle. The change in central conduction time between two test times correlates significantly with the change in ear advantage under the non-forced and forced-left attention. Conclusively, the central conduction time depends on the time during the menstrual cycle, which in turn may affect the performance in dichotic listening.

The effect of side of implantation on unilateral cochlear implant performance in patients with prelingual and postlingual sensorineural hearing loss: A systematic review.

Cerebral lateralisation of language processing leads to a right ear advantage in normal hearing subjects. The aim of this study was to present a systematic overview of the effect of implantation side on postoperative cochlear implant performance in patients with symmetrical severe to profound sensorineural hearing loss. PubMed, Embase and The Cochrane Library databases. Databases were searched from database inception up to 9 January 2017 for cochlear implant and side and all synonyms. Title, abstract and full-text of retrieved articles were screened for eligibility. Then, directness of evidence and risk of bias were assessed. For the included articles, study characteristics and outcome data (hearing and language development) were extracted. 2541 unique articles were screened, of which twenty were eligible for critical appraisal. No randomised controlled trials were identified. Twelve studies with a high directness of evidence remained for data extraction. Four of six studies including children with pre-lingual sensorineural hearing loss and four of seven studies investigating adults with postlingual sensorineural hearing loss found a right ear advantage in at least one outcome measurement related to cochlear implant performance. The available evidence on the effect of side of implantation is of low quality, as study populations and outcome measures are heterogeneous. The majority of studies reveals evidence for a right ear advantage in prelingually deafened children as well as postlingually deafened adults. In view of the present evidence and as no left ear advantage was identified, we cautiously advise implanting the cochlear implant in the right ear when other prognostic factors do not favour the left ear and sensorineural hearing loss is symmetrical.

Musical instrument dexterity requirements and its effects on adolescent diotic and dichotic listening performance

Research examining the human asymmetry of handedness has included exploring the relationship to the auditory modality (e.g., digit span memory; Bannatyne &amp; Wichiarajote, 1969). Musicians whose instruments require dual dexterity have more symmetric neural processing as a result of the sensory-motor experience with their instrument (Gaser &amp; Schlaug, 2003). Little research translates these neurological differences based on dexterity to determine if more neurologic symmetry manifests into advantages for auditory processing. This study aimed to identify perceptual advantages of instrumental training based on dexterity, during stages when the central auditory nervous system is still developing. Monaural and binaural listening tasks, as well as working memory tasks, were collected on 33 adolescent (14–18 years old) musicians split into subgroups based on their instrument dexterity requirement (mono vs. dual). The outcomes indicate that instrumental choice did not significantly impact diotic digit span performance; however, a performance asymmetry (e.g., right ear advantage) was identified for the mono dexterity group for dichotic listening tasks performance at capacity limits. Overall, the results indicate that individuals choosing musical instruments that require dual dexterity had more symmetric auditory processing which corresponds to previous evidence of more neural symmetry based on instrumental dexterity.

Does the right ear advantage persist in mature auditory systems when cognitive demand for processing increases?

Based on Kimura’s (1967) anatomical model of dichotic listening, the right ear has a slight advantage (REA) or performance asymmetry, compared with the left ear. This is due to left hemisphere dominance for language, which receives direct input from the right ear. Accurate performance on dichotic tests relies on sensory organization and memory; however, there is little evidence regarding the impact of increasing cognitive demands (i.e., number of items for recall) on auditory performance asymmetries in mature auditory systems. This study investigated 42 participants’ auditory perceptual and working memory abilities (e.g., forward and reverse digit spans, dichotic digits test, and directed ear dichotic digits test) to explore the relationships among cognitive demanded and performance asymmetries. Repeated measures ANOVA showed a significant effect for directed ear and digit list length. In addition, a priori comparison indicated significant performance asymmetry, with persistent REA when listening demands exceeded an individual’s auditory memory capacity. No significant performance differences were identified for digit list lengths relative to, or below an individual’s simple memory capacity. Overall, the study found the right ear tends to show better performance on dichotic listening tasks, even in adults, when the number of digits exceeded the participants’ digit span capacity.

Normative data for diagnosing auditory processing disorder in Norwegian children aged 7–12 years

Objective: The main purpose of this research was to obtain normative data for auditory processing tests for Norwegian speaking children. Design: Participants were administered routine audiological tests and an auditory processing test-battery consisting of Filtered Words, Competing Words, Dichotic Digits, Gaps In Noise, Duration– and Frequency Pattern, Binaural Masking Level Difference and HIST Speech in Noise test. A group of 10-year-old children were retested after two weeks. The effects ear, age and gender and the test–retest reliability were investigated. Study sample: There were 268 normal hearing children aged 7–12 years who participated in the study. Results: Results revealed no differences between genders. The children showed improving performance by age on all tests, except from the Gaps In Noise and Binaural Masking Level Difference. As expected, the children showed a right ear advantage on dichotic speech tests that decreased with age. The test–retest reliability for the tests was good, with a small learning effect on the Filtered Words test. Conclusion: Normative data were established and the preferred tests for diagnosing Auditory Processing Disorder were suggested for Norwegian children aged 7–12 years.