Differential Attention Effects on Dichotic Listening

Musical experience enhances time discrimination: Evidence from cortical responses

Time discrimination, a critical aspect of auditory perception, is influenced by numerous factors. Previous research has suggested that musical experience can restructure the brain, thereby enhancing time discrimination. However, this phenomenon remains underexplored. In this study, we seek to elucidate the enhancing effect of musical experience on time discrimination, utilizing both behavioral and electroencephalogram methodologies. Additionally, we aim to explore, through brain connectivity analysis, the role of increased connectivity in brain regions associated with auditory perception as a potential contributory factor to time discrimination induced by musical experience. The results show that the music-experienced group demonstrated higher behavioral accuracy, shorter reaction time, and shorter P3 and mismatch response latencies as compared to the control group. Furthermore, the music-experienced group had higher connectivity in the left temporal lobe. In summary, our research underscores the positive impact of musical experience on time discrimination and suggests that enhanced connectivity in brain regions linked to auditory perception may be responsible for this enhancement.

Influence of Alignment Strategies and Consonant Acoustic Features on Laterality Index in Dichotic Testing in Indian Languages

BACKGROUND

 The right ear advantage (REA) observed for dichotic CV (DCV) testing in Indian languages is seen to be smaller compared with the observations in several studies in English and other languages.

PURPOSE

 The present study aims to explore whether the differences in the temporal alignment of consonant-vowel (CV) stimuli used for the dichotic task is a contributing factor that can explain the smaller REAs observed in Indian languages.

RESEARCH DESIGN

 The study compared the laterality index (LI) values between DCV test results obtained using CV stimuli that were temporally aligned at the acoustic onset versus the burst onset, with 0 milliseconds lag between the right and left ears.

STUDY SAMPLE

 A total of 50 right-handed individuals (native speakers of Kannada language) in the age range of 17 to 30 years with normal hearing sensitivity participated in the study.

DATA COLLECTION AND ANALYSIS

 The participants' responses to the two sets of DCV stimuli were recorded and compared. LI was calculated for the overall scores as well as for specific voiced and unvoiced segment combinations. To test the reliability of the findings, 10 of the participants were re-tested using the same stimuli and the data were checked for reliability.

RESULTS

 The overall LI was 15.1% for the stimuli temporally aligned at the burst onset, whereas it was 5.7% for the stimuli temporally aligned at the acoustic onset. The difference in LI was not significant between the alignment conditions for unvoiced-unvoiced and voiced-voiced CV combinations, but this difference was significant for the unvoiced-voiced and voiced-unvoiced CV combinations. Comparing test and re-test scores showed good reliability.

CONCLUSION

 The results support our hypothesis that smaller REA observed in DCV task in Indian languages was due to the temporal alignment of CV stimuli. In the acoustic-onset-aligned condition, presenting pairs contrasting in the voicing feature tends to cancel out a relative ear advantage.

Practical guidelines to minimise language and cognitive confounds in the diagnosis of CAPD: a brief tutorial

OBJECTIVE

To provide audiologists with strategies to minimise confounding cognitive and language processing variables and accurately diagnose central auditory processing disorder (CAPD).

DESIGN

Tutorial.

STUDY SAMPLE

None.

RESULTS

Strategies are reviewed to minimise confounding cognitive and language processing variables and accurately diagnose CAPD.

CONCLUSIONS

Differential diagnosis is exceedingly important and can be quite challenging. Distinguishing between two or more conditions presenting with similar symptoms or attributes requires multidisciplinary, comprehensive assessment. To ensure appropriate interventions, the audiologist is a member of the multidisciplinary team responsible for determining whether there is an auditory component to other presenting deficits or whether one condition is responsible for the symptoms seen in another. Choice of tests should be guided both by the symptoms of the affected individual, as established in an in-depth interview and case history, the individual's age and primary language, and by the specific deficits reported to be associated with specific clinical presentations. Knowing which tests are available, their strengths and limitations, the processes assessed, task and response requirements, and the areas of the central auditory nervous system (CANS) to which each test is most sensitive provides the audiologist with critical information to assist in the differential diagnostic process.

Central auditory processing disorders in children and adults

Central auditory processing disorders (CAPD) can affect children and adults of all ages due to a wide variety of causes. CAPD is a neurobiologic deficit in the central auditory nervous system (CANS) that affects those mechanisms that underlie fundamental auditory perception, including localization and lateralization; discrimination of speech and non-speech sounds; auditory pattern recognition; temporal aspects of audition, including integration, resolution, ordering, and masking; and auditory performance with competing and/or degraded acoustic signals (American Speech-Language-Hearing Association, 2005a, b). Although it is recognized that central auditory dysfunction may coexist with other disorders, CAPD is conceptualized as a sensory-based auditory disorder. Administration of behavioral and/or electrophysiologic audiologic tests that have been shown to be sensitive and specific to dysfunction of the CANS is critical for a proper diagnosis of CAPD, in addition to assessments and collaboration with a multidisciplinary team. Intervention recommendations for CAPD diagnosis are based on the demonstrated auditory processing deficits and related listening and related complaints. This chapter provides an overview of current definitions and conceptualizations, methods of diagnosis of, and intervention for, CAPD. The chapter culminates with a case study illustrating pre- and posttreatment behavioral and electrophysiologic diagnostic findings.

Beyond DSM: the role of auditory processing in attention and its disorders

This article reviews and synthesizes recent research regarding auditory processing, attention, and their roles in generating both adaptive and maladaptive behavioral responses. Research in these areas is beginning to converge on the role of polymorphisms associated with catecholamine metabolism and transport, particularly the neurotransmitter dopamine. The synthesis offered in this article appears to be the first to argue that genetic differences in dopamine metabolism may be the common factor in four disparate disorders that are often observed to be comorbid, i.e., attention-deficit hyperactivity disorder, auditory processing disorders, developmental language disorders, and reading disorders.

Relação entre habilidades de processamento auditivo e funções neuropsicológicas em adolescentes

OBJETIVO: averiguar a existência de relações entre o desempenho em testes de processamento auditivo e em tarefas cognitivas. MÉTODOS: participaram 12 adolescentes com desenvolvimento típico, estudantes de terceiro ano do Ensino Médio de escolas privadas do estado do Rio Grande do Sul, Brasil, examinados com uma bateria de testes de PA(C) e com o Instrumento de Avaliação Neuropsicológica Breve Neupsilin. Foram realizadas análises de correlação de Pearson e análises qualitativas intertestes para comparação do desempenho na avaliação do PA(C) e na avaliação neuropsicológica. RESULTADOS: da bateria de testes PA(C), os Testes SSI - MCI - Teste de Sentenças Sintéticas com mensagem competitiva ipsilateral, SSW - Teste de Dissílabos Alternados e o teste Dicóticos de Dígitos apresentaram correlação forte significativa positiva (coeficiente de correlação de Pearson) com os subtestes do Neupsilin: atenção - contagem inversa, percepção de faces, linguagem oral automática e repetição, memória verbal episódica e memória de trabalho - span auditivo de palavras em sentenças. Alguns testes do PA(C) apresentaram maior frequência de dissociações com subtestes neuropsicológicos. As correlações encontradas indicam que os testes de PA(C) e as tarefas neuropsicológicas parecem examinar algumas habilidades cognitivas subjacentes em comum. As dissociações observadas sugerem que os processamentos auditivo e neuropsicológico são relativamente independentes e a análise intertestes do desempenho dos participantes na avaliação do PA(C), comparada ao desempenho na avaliação neuropsicológica, confirma os resultados encontrados para as questões anteriores. CONCLUSÃO: ressalta-se a necessidade de se pensar o contexto da administração dos testes de PA(C), considerando-se a relação de complementaridade da avaliação neuropsicológica e do exame de processamento auditivo.

How to Eliminate Air-bone Gaps Audiometrically: Use Too Much Masking

The excessive, indiscriminate use of masking during measurements of pure-tone bone-conduction thresholds can reduce or eliminate air-bone gaps. This may result in an abnormal, audiometrically induced bone-conduction threshold shift and suggest to the otologist the need for auditory brainstem response testing and/or magnetic resonance imaging. A case is presented in which the inappropriate use of the masking plateau method resulted in a reduction of the air-bone gap in an ear with a mild conductive hearing loss. The audiometric Weber test should be used in these cases, and nonmasked bone thresholds should be used to determine the actual level of the cochlear reserve.

The role of the interhemispheric pathway in hearing

The corpus callosum consists of heavily myelinated fibres connecting the two hemispheres. Its caudal portion and splenium contain fibres that originate from the primary and second auditory cortices, and from other auditory responsive areas. The anterior commissure in humans is much smaller than the corpus callosum, and it also contains interhemispheric fibres from auditory responsive cortical areas. The corpus callosum is exclusively present in placental mammals, while in acallosal mammals, most of the corpus callosum-related functions are carried out by the anterior commissure. The exact contribution of these two structures and of interhemispheric transfer in hearing in humans is still a matter of debate. In more recent years, human behavioural studies which employ psychoacoustic tasks designed to tap into interhemispheric transfer, combined with sophisticated neuroimaging paradigms, have helped to interpret information from animal experiments and post-mortem studies. This review will summarize and discuss the available information of the contributions of the human interhemispheric pathway in hearing in humans from behavioural, neuroimaging and histopathological studies in humans.

Identification of binaural integration deficits in children with the Competing Words Subtest: standard score versus interaural asymmetry

The Competing Words Subtest is a commonly used dichotic listening test for assessing binaural integration in children suspected of having an auditory processing disorder. In 124 children, standard scores from the subtest suggested a binaural integration deficit in 23% of the children tested. Because standard scores are derived from the combined scores of both ears during the test, children with normal performance in one ear and weak performance in the other ear may be overlooked. For these children, a measure of interaural asymmetry may be a more sensitive indicator of a binaural integration deficit. When an age-appropriate criterion for interaural asymmetry from the Competing Words Subtest was used, the incidence of a binaural integration deficit increased to 51% of the children tested. Four typical patterns of dichotic listening performance were identified based on results from the two scoring techniques.

Identification of binaural integration deficits in children with the Competing Words Subtest: standard score versus interaural asymmetry

The Competing Words Subtest is a commonly used dichotic listening test for assessing binaural integration in children suspected of having an auditory processing disorder. In 124 children, standard scores from the subtest suggested a binaural integration deficit in 23% of the children tested. Because standard scores are derived from the combined scores of both ears during the test, children with normal performance in one ear and weak performance in the other ear may be overlooked. For these children, a measure of interaural asymmetry may be a more sensitive indicator of a binaural integration deficit. When an age-appropriate criterion for interaural asymmetry from the Competing Words Subtest was used, the incidence of a binaural integration deficit increased to 51% of the children tested. Four typical patterns of dichotic listening performance were identified based on results from the two scoring techniques.

Verbal Dichotic Listening in Right and Left-Handed Adults: Laterality Effects of Directed Attention

Dichotic listening performance of consonant vowel stimuli was studied in 51 adult right- and left-handers in three attention conditions: non-directed and directed to either the right or left ear. In the non-directed condition, a significant right-ear advantage was found in both handedness groups with a stronger asymmetry in right-handers. There are at least three explanations for this ear bias. The classic or structural hypothesis suggests that to the right ear projects more strongly to the language dominant left hemisphere. The callosal relay hypothesis is based on the influence of inhibitory connections via the corpus callosum. The attentional hypothesis suggests that each hemisphere primarily directs attention to contralateral space and because the left hemisphere is dominant for language in both groups, and is aroused by speech stimuli, attention is primarily directed to the right ear. Neither hypothesis can explain why greater than 95% of right-handers have left hemisphere language dominance, but only 70-80% have a right ear bias. Our results demonstrate that in the directed attention conditions both groups increased their lateral biases when directed to either the right or left. The classic or structural hypothesis cannot account for these changes, thereby providing support for the attentional hypothesis. In addition, the right-handed subjects exhibited a greater shift of bias than did the left-handed subjects, when directing their attention leftward. This finding suggests that right-handed people are better able to shift their attention than left-handed people.