Dichotic listening deficits in amblyaudia are characterized by aberrant neural oscillations in auditory cortex.

OBJECTIVE: Children diagnosed with auditory processing disorder (APD) show deficits in processing complex sounds that are associated with difficulties in higher-order language, learning, cognitive, and communicative functions. Amblyaudia (AMB) is a subcategory of APD characterized by abnormally large ear asymmetries in dichotic listening tasks. METHODS: Here, we examined frequency-specific neural oscillations and functional connectivity via high-density electroencephalography (EEG) in children with and without AMB during passive listening of nonspeech stimuli. RESULTS: Time-frequency maps of these "brain rhythms" revealed stronger phase-locked beta-gamma (~35 Hz) oscillations in AMB participants within bilateral auditory cortex for sounds presented to the right ear, suggesting a hypersynchronization and imbalance of auditory neural activity. Brain-behavior correlations revealed neural asymmetries in cortical responses predicted the larger than normal right-ear advantage seen in participants with AMB. Additionally, we found weaker functional connectivity in the AMB group from right to left auditory cortex, despite their stronger neural responses overall. CONCLUSION: Our results reveal abnormally large auditory sensory encoding and an imbalance in communication between cerebral hemispheres (ipsi- to -contralateral signaling) in AMB. SIGNIFICANCE: These neurophysiological changes might lead to the functionally poorer behavioral capacity to integrate information between the two ears in children with AMB.

An optimal dichotic-listening paradigm for the assessment of hemispheric dominance for speech processing.

Dichotic-listening paradigms are widely accepted as non-invasive tests of hemispheric dominance for language processing and represent a standard diagnostic tool for the assessment of developmental auditory and language disorders. Despite its popularity in research and clinical settings, dichotic paradigms show comparatively low reliability, significantly threatening the validity of conclusions drawn from the results. Thus, the aim of the present work was to design and evaluate a novel, highly reliable dichotic-listening paradigm for the assessment of hemispheric differences. Based on an extensive literature review, the paradigm was optimized to account for the main experimental variables which are known to systematically bias task performance or affect random error variance. The main design principle was to minimize the relevance of higher cognitive functions on task performance in order to obtain stimulus-driven laterality estimates. To this end, the key design features of the paradigm were the use of stop-consonant vowel (CV) syllables as stimulus material, a single stimulus pair per trial presentation mode, and a free recall (single) response instruction. Evaluating a verbal and manual response-format version of the paradigm in a sample of N = 50 healthy participants, we yielded test-retest intra-class correlations of rICC = .91 and .93 for the two response format versions. These excellent reliability estimates suggest that the optimal paradigm may offer an effective and efficient alternative to currently used paradigms both in research and diagnostic.

The development of the listening in spatialised noise - universal test (LiSN-U) and preliminary evaluation in English-speaking listeners.

Objective: To create a language independent version of the Listening in Spatialised Noise - Sentences test (LiSN-S) and evaluate it in an English-speaking population.Design: Test development and normative data collection. LiSN-Universal (LiSN-U) targets consisted of CVCV pseudo-words (e.g. /mupa/). Two looped distracter tracks consisted of CVCVCVCV pseudo-words. The listener's task was to repeat back the target pseudo-words. Stimuli were presented over headphones using an iPad. Speech reception thresholds were measured adaptively. In the co-located condition all stimuli came from directly in front. In the spatially-separated condition the distracters emanated from +90° and -90° azimuth. Perceived location was manipulated using head-related transfer functions. Spatial advantage was calculated as the difference in dB between the co-located and spatially separated conditions.Study samples: Stimulus intelligibility data were collected from 20 adults. Normative data were collected from native English speakers (23 adults and 127 children).Results: Children's spatially separated, co-located, and spatial advantage results improved significantly with age. Spatial advantage was 4-6 dB larger in the LiSN-U than LiSN-S depending on age group.Conclusion: Whereas additional research in non-native English populations is required, the LiSN-U appears to be an effective tool for measuring spatial processing ability.

Perceptual organization of sequential stimuli in cochlear implant listeners: A temporal processing approach.

OBJECTIVE: Cochlear Implant (CI) users often suffer difficulties in perceiving speech in noisy environments that could be attributed to reduced Auditory Stream Segregation (ASS) ability. ASS is the process used to separate a complex sound into different perceptual streams. The evidence that CI listeners routinely experience stream segregation skill is limited and equivocal. The present study was aimed to investigate the effects of temporal cues on ASS performance in postlingually deaf listeners with CI. METHODS: Nineteen (age range: 28-64 years old) monaurally cochlear implanted listener participated in this study. They were presented with 30-s sequences of alternating stimuli in a repeating A-B-A-A-B-A…sequence, where "tone A" corresponds to a stimulus applied to electrode 11, and "tone B" to a stimulus on one of the other electrode. To investigate the effect of temporal cues on ASS, four different tone repetition times (TRTs) were utilized: 50, 100, 150, and 200 ms. Speech discrimination scores in noise were also recorded for every CI recipients. RESULTS: Only 6 (32%) CI users demonstrated ASS pattern similar to the normal hearing subjects, while the majority of the users (n=13) possessed poorer ASS skills. An analysis of variance showed a significant effect of electrode separation (p<0.001) and TRT (p=0.041), but there was no significant interaction between electrode separation and TRT variables. The best ASS performance was obtained when TRT was 200 ms, and there was no significant effect for other TRT conditions. Moderate, significant correlations between streaming and speech discrimination measurement in noise was also observed (r=0.62), with better stream segregation associated with better understanding of speech in noise. CONCLUSION: ASS is a contributing factor in the ability to perceive speech in background noise. The inability of some CI recipients to perform stream segregation may therefore contribute to their difficulties in noisy backgrounds. Furthermore, stream segregation ability is related to the tone repetition time between the sounds.

A primer on dichotic listening as a paradigm for the assessment of hemispheric asymmetry.

Dichotic listening is a well-established method to non-invasively assess hemispheric specialization for processing of speech and other auditory stimuli. However, almost six decades of research also have revealed a series of experimental variables with systematic modulatory effects on task performance. These variables are a source of systematic error variance in the data and, when uncontrolled, affect the reliability and validity of the obtained laterality measures. The present review provides a comprehensive overview of these modulatory variables and offers both guiding principles as well as concrete suggestions on how to account for possible confounding effects and avoid common pitfalls. The review additionally provides guidance for the evaluation of past studies and help for resolving inconsistencies in the available literature.

Auditory temporal resolution in adaptive tasks. Gap detection investigation.

OBJECTIVES: To study auditory temporal resolution skills using adaptive auditory tasks designed with a computer-based experimental program, and to provide normative valuesfor gap detection thresholds (GDTs) of young listeners in 3 listening conditions. Methods:  The GDTs were established under 3 stimulus conditions: 1) broadband noise (BBN), 2) narrowband noise within-channel (NBN WC) using similar leading and trailing markers centered at 1.0 KHz, and 3) narrowband noise across-channel (NBN AC) with the leading marker centered at 2.0 KHz and the trailing marker centered at 1.0 KHz. In within-subjects design, the GDTs were obtained from 27 normal hearing young Saudi adults at Speech and Hearing Laboratories, Department of Rehabilitation Health Sciences, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia between April 2017 and April 2018. Results: The mean GDTs for the BBN condition was 3.19 millisecsond (msec), NBN WC was 14.53 msec, and NBN AC was 29.71 msec. Our findings for the GDTs measured in the 3 conditions were consistent with those of earlier investigations that used different instrumentations. Also, no correlations among the GDTs of the 3 stimulus conditions were found. Conclusion: The present study showed that experimental program is a reliable tool with clinical potential to estimate GDTs across different conditions. Also, the findings of no correlations in the GDTs across stimulus conditions suggest that different processes were involved in the perception of the temporal gap for different stimulus conditions.

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.

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.

Evidence-based interventions of dichotic listening training, compensatory strategies and combined therapies in managing pupils with auditory processing disorders.

OBJECTIVE: The need to develop a measure of managing children with a single profile of auditory processing disorders (APDs), and differentiate between true and artefactual improvements necessitated the study. The study also sought to determine the efficacy of interventions - both single and combined on APD, against no-treatment. DESIGN: A randomised controlled trial of interventions (RCT) was adopted. Participants were randomly allocated to each of the intervention groups or the no intervention group. The 10 weeks intervention included 45 minutes three times a week therapeutic intervention on listening with noise and sound localisation ability in the home and school environments. STUDY SAMPLE: 80 pupils (7-11 years) with a single profile of APD participated in the study. RESULTS: Treatments were effective on the cocktail party and sound localisation. The best result was realised with the combined therapy (CT), and there was no significant difference in performance in the remaining treatment groups. CONCLUSION: The intervention groups were beneficial to pupils with APD and should be adopted by clinicians.

Enhanced Identification of Long Versus Short Voice Onset Time Consonant-Vowel Syllables in a Dichotic Listening Task.

PURPOSE: This study investigated the influence of voice onset time (VOT) on the perception of consonant-vowel (CV) signals during a dichotic listening (DL) task. METHOD: Sixty-two young adults with normal hearing were tested with the English language version of the Hugdahl Dichotic CV (DCV) Test. They were asked to identify 1 CV syllable during 3 DL conditions: free recall (report the syllable heard most clearly), forced right (report the syllable in the right ear), and forced left (report the syllable in the left ear). Averages for number and percent correct syllables were recorded under each condition and across the entire test. RESULTS: All subjects demonstrated an overall right-ear advantage (REA) when scores from all 3 listening conditions were averaged. The REA occurred for all VOT pairings except when the long VOT was presented to the left ear, whereas the short VOT was presented to the right ear when subjects produced an average left-ear advantage. The left-ear advantage overcame the structural advantage of the right ear even when subjects were directed to attend to the right ear. This result was consistent with findings of earlier studies done with Norwegian and Australian subjects. CONCLUSIONS: Listeners' REA may be overcome by interaural temporal differences that favor processing in the listener's nondominant ear during the DCV test. Balanced VOT conditions across the DCV test prevent this effect from producing an overall bias toward the left ear, but clinical DL tests with consonant-vowel-consonant words should be examined for effects of the long VOT on laterality of performance.

Eficacia de las intervenciones para el tratamiento de la dislexia: una revisión / Effectiveness of interventions for the treatment of dyslexia: a review

En este informe se revisa la investigación que respalda distintas intervenciones para el tratamiento de la dislexia, concretamente los trabajos de síntesis, en especial síntesis de las mejores evidencias, revisiones sistemáticas o metaanálisis publicados sobre cada tipo de intervención. En los casos en que no se ha publicado ningún trabajo de síntesis o estos trabajos son antiguos, se hace una revisión de la investigación primaria. Los trabajos localizados indican que los métodos fonológicos de intervención en la dislexia, es decir, aquellos en los que se combina el entrenamiento en habilidades fonológicas con el conocimiento de las letras y la práctica de la lectura, están ampliamente respaldados por la investigación. En cambio, la investigación sobre otros sistemas es sumamente escasa, ofrece resultados contradictorios o indica que se trata de sistemas ineficaces. Las intervenciones que están en estas situaciones son: la integración auditiva, el entrenamiento auditivo con soporte informático, la terapia visual, las lentes tintadas, el entrenamiento perceptivo-motor, las técnicas quiroprácticas, la integración sensorial, el método Davis, el neurofeedback, la musicoterapia y la educación musical o las dietas y suplementos alimenticios. A partir de esta revisión se realizan las siguientes recomendaciones: promocionar las intervenciones de tipo fonológico para el tratamiento de la dislexia, no utilizar o recomendar intervenciones que no estén respaldadas por la investigación científica, que los métodos de intervención que no hayan probado su eficacia no reciban el nombre de «terapia» o «tratamiento», y la creación y difusión de una guía sobre intervención en dislexia basada en evidencias científicas (AU)

In this report the research that supports various interventions for the treatment of dyslexia is revised, specifically the works of synthesis, especially synthesis of best evidence, systematic reviews or meta-analyses published about each type of intervention. A review of primary research is made in cases in which no synthesis work has been published or where these works are old. Localised works indicate that the phonological methods of intervention in dyslexia, i.e. those in which training in phonological skills is combined with knowledge of letters and the practice of reading, are widely supported by research. However, research on other methods is either extremely scarce or it offers conflicting results or it leads to the conclusion that they are inefficient methods. Interventions in this situation are: the auditory integration, the auditory training with computer support, visual therapy, the tinted lenses, motor-perceptual training, chiropractic techniques, sensory integration, the Davis method, neurofeedback, music therapy and music education or diets and dietary supplements. Promotion of phonological interventions is recommended; it is necessary to avoid recommendations of intervention methods for dyslexia which are not supported by scientific research; methods of intervention that have not proven their effectiveness may not be presented as therapies or treatments; and the creation and distribution of a guide on intervention in dyslexia based on scientific evidence is recommended (AU)

Oscillatory decoupling differentiates auditory encoding deficits in children with listening problems.

OBJECTIVE: We sought to examine whether oscillatory EEG responses to a speech stimulus in both quiet and noise were different in children with listening problems than in children with normal hearing. METHODS: We employed a high-resolution spectral-temporal analysis of the cortical auditory evoked potential in response to a 150 ms speech sound /da/ in quiet and 3 dB SNR in 21 typically developing children (mean age=10.7 years, standard deviation=1.7) and 44 children with reported listening problems (LP) with absence of hearing loss (mean age=10.3 years, standard deviation=1.6). Children with LP were assessed for auditory processing disorder (APD) by which 24 children had APD, and 20 children did not. Peak latencies, magnitudes, and frequencies were compared between these groups. RESULTS: Children with LP had frequency shifts in the theta, and alpha bands (p<0.05), and children with LP+APD had additional frequency (p<0.01) and latency shifts (p<0.05) in the upper beta and in the lower gamma bands. CONCLUSIONS: These results provide evidence for differences in higher level modulatory processing in children with LP, and that APD is driven by differences in early auditory encoding. SIGNIFICANCE: These findings may better guide future research toward improving the differential diagnosis and treatment of listening problems in this population of children.

Robust extraction of the N1-effect in dichotic listening using hardy space mappings of auditory late single trials.

It is known that signs of (early) auditory selective attention are reflected in the N1-wave of auditory late potentials. In recent years, we have analyzed this N1-effect using multiscale neurofunctional modeling and (instantaneous) phase synchronization measures of Hardy space mapped data. To acquire the electroencephalographic data in dichotic listening, we repeated the seminal experiment of Hillyard et al. which first described the N1-effect. Here we apply for the first time phase synchronization measures to these dichotic data and compare the results to the conventional time-domain analysis. Our results suggest that a single trial synchronization analysis of the instantaneous phase at the α/θ-border shows the N1-attention effect even more clear than the original averaged time-domain representation. It is concluded that the presented method is a robust tool to analyse (early) signs of selective attention in dichotic listening tasks.

Isolating informational masking in both pure and complex tone sequences.

OBJECTIVES: Interference between a target and simultaneous maskers occurs both at the cochlear level through energetic masking and more centrally through informational masking (IM). Hence, quantifying the amount of IM requires a strict control of the energetic component. Presenting target and maskers on different sides (i.e., dichotically) reduces energetic masking but provides listeners with important lateralization cues that also drastically reduce IM. The main purpose of this study (Experiment 1) was to evaluate a "switch" manipulation aiming at restoring most of the IM despite dichotic listening. Experiment 2 was designed to investigate the source of the difficulty induced by this switching dichotic condition. DESIGN: In Experiment 1, the authors presented 60 normal-hearing young adults with a detection task in which a regularly repeating target was embedded in a randomly varying background masker. The authors evaluated spatial masking release induced by three different dichotic listening conditions in comparison with a diotic baseline. Dichotic stimuli were presented in either a nonswitching or a switching condition. In the latter case, the presentation sides of dichotic target and maskers alternated several times throughout 10 sec sequences. The impact of the number of switches on IM was investigated parametrically, with both pure and complex tone sequences. In Experiment 2, the authors compared performance of 13 young, normal-hearing listeners in a monotic and dichotic version of the rapidly switching condition, using pure-tone sequences. RESULTS: When target and maskers switched rapidly within sequences, IM was significantly stronger than in nonswitching dichotic sequences and was comparable with the masking effect induced by diotic sequences. Furthermore, Experiment 2 suggests that rapidly switching target and maskers prevent listeners from relying on lateralization cues inherent to the dichotic condition, hence preserving important amounts of IM. CONCLUSIONS: This paradigm thus provides an original tool to isolate IM in signal and maskers having overlapping spectra.

Atypical right hemispheric functioning in the euthymic state of bipolar affective disorder.

Bipolar disorder (BD) has been associated with right hemisphere dysfunction. These findings usually come from studies that have not distinguished between symptomatic and euthymic states of BD. The present study aims to investigate atypical right (and left) hemispheric functioning in euthymic BD patients. We evaluated 40 participants (18 healthy controls and 22 euthymic BD patients) using an emotional prosody dichotic listening task and a linguistic dichotic listening task which have been shown to produce a strong left ear advantage (LEA) and right ear advantage (REA), indicating a right and left hemisphere superiority, respectively. The results replicate the well-known LEA in emotional prosody for healthy controls. In contrast, no ear advantage was found for emotional prosody in euthymic BD patients. Both groups revealed the well-established REA in the linguistic dichotic listening task. The patient group was heterogeneous with regard to medication, as it consisted of patients with a variety of pharmacological treatments. The results are in line with previous studies in symptomatic BD patients, and suggest that atypical LEA in emotional prosody can be interpreted as a neurobehavioral vulnerability marker of emotional dysregulation and dysfunction in the right hemispheric fronto-temporal network in both symptomatic and euthymic BD patients.

The effect of middle age on the late positive component of the auditory event-related potential.

BACKGROUND: We recently described a research study in which age-related changes in interaural asymmetry were elicited using the N400 of the auditory event-related potentials (AERP) (Davis et al, 2013). The N400 was the primary focus due to its sensitivity to various aspects of semantic processing (Kutas and Hillyard, 1984), which we measured using a quasi-dichotic semantic category judgment task in competing speech. In this article, we describe age-related changes that occurred in the late positive component (LPC) of the AERP in the same study. The LPC peak occurs subsequent to the N400 peak on the AERP waveform and has been associated with context updating and further evaluation and processing of stimulus meaning (Juottonen et al, 1996). Neither age group showed significant interaural asymmetry in the LPC. However, a robust age-related difference in LPC scalp topography was observed. PURPOSE: The LPC of the auditory event-related potentials was utilized to evaluate age-related differences in language processing in a quasi-dichotic competing speech task. RESEARCH DESIGN: Electrophysiological responses were obtained on a word-pair semantic categorization task presented through a front loudspeaker while ignoring competing speech that was presented through either left (competition left [CL]) or right (competition right [CR]) loudspeakers. The LPC was compared between young and middle-aged groups in three conditions: side of competition, semantic judgment, and electrode position. STUDY SAMPLE: Twenty young (18-24 yr) and twenty middle-aged (44-57 yr) females with normal hearing sensitivity participated in this study. DATA COLLECTION AND ANALYSIS: Individual, as well as grand-averaged, AERP waveforms and scalp topographies were analyzed in response to the word pairs. The LPC component was subjected to a mixed design analysis of variance (ANOVA) for peak latency and amplitude measures in the latency range of 700-800 msec. Since statistical analyses showed little difference in the LPC component as a function of side of competition, the AERP data were collapsed for the CL and CR conditions. The LPC was analyzed in two ways: first at mid-parieto-central electrode locations, second across midline electrodes from PZ to FZ. RESULTS: Analysis of the mid-parieto-central electrodes showed no amplitude or latency differences for either group or side of competition. The second analysis (across midline electrodes), however, showed a significant amplitude interaction between electrode position and group, indicating that the two age groups were equivalent in the posterior region of the scalp but divergent as electrode site moved frontally. Significant age-related scalp topography differences were found in both semantic judgment conditions. No significant latency differences were found in any condition. CONCLUSIONS: The middle-aged group showed substantially greater LPC peak amplitude in the frontal regions of the scalp than young adults. These results were in concert with N400 results, which suggested that the middle-aged group required more attentional/cognitive resources than young adults in order to maintain a high performance level on a linguistic task in the presence of competing linguistic stimuli (Davis et al, 2013).

Dichotic assessment of verbal memory function: development and validation of the Persian version of Dichotic Verbal Memory Test.

BACKGROUND AND PURPOSE: The Dichotic Verbal Memory Test (DVMT) is useful in detecting verbal memory deficits and differences in memory function between the brain hemispheres. The purpose of this study was to prepare the Persian version of DVMT, to obtain its results in 18- to 25-yr-old Iranian individuals, and to examine the ear, gender, and serial position effect. RESEARCH DESIGN: The Persian version of DVMT consisted of 18 10-word lists. After preparing the 18 lists, content validity was assessed by a panel of eight experts and the equivalency of the lists was evaluated. Then the words were recorded on CD in a dichotic mode such that 10 words were presented to one ear, with the same words reversed simultaneously presented to the other ear. Thereafter, it was performed on a sample of young, normal, Iranian individuals. STUDY SAMPLE: Thirty normal individuals (no history of neurological, ontological, or psychological diseases) with ages ranging from 18 to 25 yr were examined for evaluating the equivalency of the lists, and 110 subjects within the same age range participated in the final stage of the study to obtain the normative data on the developed test. RESULTS: There was no significant difference between the mean scores of the 18 developed lists (p > 0.05). The mean content validity index (CVI) score was .96. A significant difference was found between the mean score of the two ears (p < 0.05) and between female and male participants (p < 0.05). CONCLUSION: The Persian version of DVMT has good content validity and can be used for verbal memory assessment in Iranian young adults.

Monotic versus dichotic multiple-stimulus auditory steady state responses in young children.

In their recent study on infant multiple auditory steady state responses (ASSR), the authors found that ASSR amplitudes unexpectedly decreased when switching from 1-ear stimulation to 2-ear stimulation, a result not present in adults. In addition, residual EEG noise levels increased in the 2-ear condition. In the present study, to determine whether to use 1-ear or 2-ear multiple ASSR Protocols clinically, the authors tested a new group of 19 young children to determine whether these unexpected findings could be replicated. ASSR amplitude and EEG noise were compared for 1-ear (4 stimuli) versus 2-ear (8 stimuli) multiple stimuli presented at 60 dBHL. Results indicated a small but significant decrease in amplitudes going from 1-ear (40.1 nV) to 2-ear (37.9 nV) multiple stimuli. EEG noise was not significantly different between the 2 conditions. Despite small amplitude decreases, the 2-ear stimulus condition was more efficient for infants and young children with normal hearing.

Resolução temporal em perdas auditivas sensorioneurais / Temporal resolution in sensorineural hearing loss

OBJETIVO: Avaliar a resolução temporal em adultos com perdas auditivas sensorioneurais de graus leve e moderado, por meio do teste Gaps in Noise (GIN), a fim de verificar se essas perdas influenciam no desempenho do teste. MÉTODOS: Foram avaliados 57 pacientes, com idades entre 20 e 59 anos (30 homens e 27 mulheres), que realizaram anamnese, avaliação otorrinolaringológica, avaliação audiológica básica e triagem do processamento auditivo, com o teste Dicótico de Dígitos. Os sujeitos foram alocados nos grupos G1 (audição normal), G2 (perda auditiva leve) e G3 (perda moderada). Foi realizada análise estatística apropriada e o nível de significância adotado foi de 5%. RESULTADOS: Observou-se presença significativa de homens no grupo com perda auditiva. Não foram encontradas diferenças significativas no desempenho do referido teste entre os grupos. Porém, no grupo controle, foram observados piores desempenhos, quando comparados com o critério de normalidade previsto para adultos jovens brasileiros. A média do limiar de detecção de gaps, da amostra geral, foi de 8,2 ms, em ambas as orelhas, e a média das porcentagens de acertos foi de 49,7% para a orelha direita (OD) e de 50,6% para a orelha esquerda (OE). CONCLUSÃO: A habilidade de resolução temporal avaliada pelo teste GIN não sofre influência da perda auditiva sensorioneural de graus leve e moderado, tanto nos limiares de detecção de gaps quanto na porcentagem de acertos, em ambas as orelhas.

PURPOSE: To evaluate temporal resolution in adults with mild and moderate sensorineural hearing loss using the Gaps in Noise (GIN) test to determine whether these losses affect the test performance. METHODS: Fifty-seven patients between 20 and 59 years of age (30 men and 27 women) were evaluated; these patients had a complete medical history taken and underwent ENT examination, basic audiological evaluation, and auditory screening via the dichotic digits test. The subjects were divided into three groups: G1 (normal hearing), G2 (mild hearing loss), and G3 (moderate hearing loss). The appropriate statistical analysis was performed, and the adopted level of significance was 5%. RESULTS: A significant proportion of men was observed in the group with hearing loss. There were no significant differences in test performance between the groups. However, the control group's performance was worse than the normality criteria set for young Brazilian adults. The mean gap detection threshold for the total sample was 8.2 ms in both ears, and the mean percentage of correct responses was 49.7% for the right ear (RE) and 50.6% for the left ear (LE). CONCLUSION: The temporal resolution evaluated by the GIN test was not influenced by mild-to-moderate sensorineural hearing loss either in the gap detection thresholds or in the percentage of correct responses for both ears.

Auditory evoked potentials of adults who do or do not show a significant right ear advantage in dichotic listening.

The Halwes Fused Dichotic Words Test was used to divide a sample of university students into a group having a statistically significant right ear advantage (REA) and a group having either a significant left ear advantage or a non-significant ear asymmetry (NREA). Of these participants, 30 (14 REA, 16 NREA) had electrical potentials measured from temporal, central, and frontal sites as series of brief tones were presented monaurally. No behavioural response was required. Group differences were found in the latency but not the amplitude of the averaged event-related responses. The REA group showed faster conduction to the right hemisphere than to the left hemisphere. In both groups the amplitude of left hemisphere responses was greater for right ear stimulation than for left ear stimulation. The results for amplitude indicate that the crossed auditory pathway is a superior conductor of information to the left hemisphere but not to the right hemisphere. Group differences, however, are related only to the speed with which information reaches the right hemisphere.