published_or_final_version / abstract / Speech and Hearing Sciences / Master / Master of Science in Audiology

Dichotic tests evaluate binaural integration through simultaneous presentation of different stimuli to each ear of a listener who has normal hearing sensitivity in both ears. Dichotic listening deficits may lead to problems with language, communication, reading, or academic performance. If accurately identified, dichotic deficits may be treatable with listening training or managed with accommodation. However, it is not clear which of several commercially-available dichotic test recordings are best for audiologists to use when assessing binaural integration in children. Literature review revealed limited evidence of reliability, accuracy, usefulness, or value for dichotic tests applied to children. Of 11 dichotic tests identified, five reported some evidence of test-retest reliability. Correlation between results on repeated administration was moderate to good (r=0.59 to 0.92). Evidence of accuracy was identified for 5 tests but was not generalizable due to significant limitations in study design. No evidence was found to either support or dispute claims of usefulness or value. Since reliability is a necessary prerequisite for good test performance, we sought to directly compare test-retest reliability for three dichotic measures: SCAN-3 Competing Words (CW), Musiek's Double Dichotic Digits (DD-M), and Bergen Dichotic Listening Test with Consonant-Vowel Syllables (CV-B). Sixty English-speaking children, 7-14 years old with normal hearing, had a single study-visit during which each test was administered twice. Changes on retest were compared to binomial model predictions, summarized by within-subject standard deviation (Sw), and compared among tests. Correlates of variance were explored. All 3 tests had reliability within bounds predicted by binomial model. Forty-item scores were more reliable (Sw=5%) than those based on 20-30 items (Sw=6-8%). No associations between participant characteristics and reliability were found. CW and DD-M were evaluated for evidence of agreement and decision consistency. Although participants were rank ordered similarly by right ear (ρ = 0.58), left ear (ρ = 0.51) and total (ρ = 0.73) scores, the tests did not agree on ranking by inter-aural asymmetry (ρ =0.18). CW and DD-M did not agree on direction of ear advantage (κ = 0.01, p = 0.93) and had poor agreement on which children displayed dichotic deficits (κ = 0.22, p < 0.01). DD identified significantly more participants with deficits (n=18) than CW (n=3) (p < 0.001). Although dichotic procedures show moderate reliability, their precision is limited. Assessment of their accuracy is limited by the absence of a widely-accepted gold standard reference test, but two commonly used tests failed to agree on which children had deficits. The data do not yet support routine clinical use of dichotic tests of binaural integration with children. Additional research is needed to determine if there are any conditions under which dichotic procedures demonstrate usefulness or value.

Diss. Linköping : Universitetet, 2005.

The new compact disc from the Department of Veterans Affairs, Tonal and Speech Materials for Auditory Perceptual Assessment, Disc 2.0 (1998), contains two lists of randomly interleaved 1-, 2-, and 3-pair dichotic digits. Two experiments are reported, in which the effects of low-pass filtering and inter-digit interval on dichotic digit recognition were investigated in adult listeners with normal hearing and with mild-to-moderate cochlear hearing loss. Results demonstrated that in the filtered condition, as the low-pass cutoff was increased, there was an increase in recognition performance for 1-, 2-, and 3-pair dichotic digits. When compared to normative data for the materials, findings indicate that the interleaved 1-, 2-, and 3-pair dichotic digit materials were essentially resistant to the effects of hearing loss. There was no significant change in recognition performance as a function of inter-digit interval. The studied 625-ms range of inter-digit intervals studied produced consistent recognition performance with both groups of listeners.

Dichotic listening was evaluated in free-recall and directed-recall (pre-cued, post-cued) response conditions using interleaved one-, two-, and three-pair dichotic digit materials. In the free-recall condition, the subjects recalled in any order the digits presented. In the directed-recall condition, a response task was examined where subjects recalled all digits presented to the cued ear (pre- or post-cued) followed by the digits presented to the opposite (non-cued) ear. Thirty 20- to 29-year-old adults with normal hearing and 30 60- to 79-year-old adults with mild-to-moderate sensorineural hearing loss were evaluated. In all conditions, performance by the younger listeners was better than performance by the elderly listeners. As the difficulty of the dichotic digit task increased, recognition performance decreased. The recognition performance of elderly listeners was more affected by increases in the difficulty of the stimulus materials as compared to the younger listeners. In the free-recall condition, there was a right-ear advantage for both age groups. When instructional bias was imposed, the results favored the ear of instructed bias. The differences in recognition performance between young and elderly listeners likely reflect differences in the difficulty of the dichotic digit test conditions and variations in the demand on auditory memory.

The Dichotic Emotional Words Tape developed by Bryden and MacCrae (1989) was used to assess cerebral asymmetry for propositional and nonpropositional speech as a function of verbal fluency. Forty-five right-handed subjects with normal auditory acuity for pure tones were assigned to a verbal fluency classification based on scores on the FAS test (Borkowski, Benton, & Spreen, 1967). After being assigned to a fluency category, subjects were instructed to listen for a word (bower, dower, power, or tower) or affective tone (happy, sad, angry, or neutral). The most important findings of this study were the main effects of fluency (higher, middle, and lower), stimulus type (word and affect), and focus or intention (focus left and focus right). Subjects higher in fluency exhibited significantly greater REA and LEA scores than subjects lower in fluency. For stimuli presented to the right ear, scores for words were significantly greater than scores for affect. However, for stimuli presented to the left ear, scores for affect were significantly greater than scores for words. Focus left instructions led to increases in LEA scores, while focus right instructions led to increases in REA scores. Directions for future research are discussed. / Master of Science

Realizou-se um inventário quantitativo e qualitativo das características demográficas e dos erros cometidos nos itens dicóticos do Teste de Dissílabos Dicóticos Alternados, também conhecido como SSW em português, com as informações de 722 sujeitos que completaram este teste nos anos de 1994 a 2001. Os resultados revelaram que a amostra estudada foi composta em sua maioria de sujeitos do sexo masculino, cursando as séries iniciais do ensino fundamental, relatando dificuldades de fala, escria e leitura e neurologicamente normais, com desordem de processamento auditivo do tipo decodificação, de grau leve/moderado. Uma tendência de erro em alguns itens dicóticos do teste foi observada. / A total of 722 subjects provided the information for the quantitative and qualitative inventory of demographic features and the errors observed in the dichotic items of the Portuguese version of the SSW Test. Results revealed that, collectively, these subjects were mostly males, in elementary school, referring speech, reading and writing difficulties, and not presenting neurological disorders. They also presented a decoding-type auditory processing disorder of mild/moderate severity. Error and performance profiles were characterized by multivariate statistics.

Central auditory processing is complex and can not be evaluated by a single method. This thesis focuses on assessment of some aspects of central auditory functions by the use of dichotic speech tests and cognitive tests that tax functions important for speech processing. Paper A deals with the cognitive effects in dichotic speech testing in elderly hearing-impaired subjects. It was found that different listening tasks in the dichotic tests put different demands on cognitive ability, shown by a varying degree of correlation between cognitive functions and dichotic test parameters. Age-related cognitive decline was strongly connected with problems to perceive stimuli presented to the left ear. Paper B presents a new cognitive test battery sensitive for functions important for speech processing and understanding, performed in text, auditory and audiovisual modalities. The test battery was evaluated in four groups, differing in age and hearing status, and has proven to be useful in assessing the relative contribution of different input-modalities and the effect of age, hearingimpairment and visual contribution on functions important for speech processing. In Paper C the test battery developed in Paper B was used to study listening situations with different kinds of background noise. Interfering noise at +10 dB signal-to-noise ratio has significant negative effects on performance in speech processing tasks and on the effort perceived. Hearing-impaired subjects showed poorer results in noise with temporal variations, and elderly subjects were more distracted by noise with temporal variations, especially by noise with meaningful content. In noise, all subjects, particularly those with impaired hearing, were more dependent upon visual cues than in the quiet condition. Hearing aid benefit in speech processing with and without background noise was studied in Paper D. The test battery developed in Paper B was used together with a standard measure of speech recognition. With hearing aids, speech recognition was improved in the background condition without noise and in the background condition of ordinary speech. Significantly less effort was perceived in the cognitive tests when hearing aids were used, although only minor benefits of hearing aid amplification were seen. This underlines the importance of considering perceived effort as a dimension when evaluating hearing aid benefit, in further research as well as in clinical practice. The results from the studies contribute to the knowledge about speech processing but also to the search for more specific evaluation of speech understanding, incorporating both sensory and cognitive factors. / The ISBN 91-85297-49-6 in the printed verison is incorrect. The correct ISBN is 91-85297-93-3.

Realizou-se um inventário quantitativo e qualitativo das características demográficas e dos erros cometidos nos itens dicóticos do Teste de Dissílabos Dicóticos Alternados, também conhecido como SSW em português, com as informações de 722 sujeitos que completaram este teste nos anos de 1994 a 2001. Os resultados revelaram que a amostra estudada foi composta em sua maioria de sujeitos do sexo masculino, cursando as séries iniciais do ensino fundamental, relatando dificuldades de fala, escria e leitura e neurologicamente normais, com desordem de processamento auditivo do tipo decodificação, de grau leve/moderado. Uma tendência de erro em alguns itens dicóticos do teste foi observada. / A total of 722 subjects provided the information for the quantitative and qualitative inventory of demographic features and the errors observed in the dichotic items of the Portuguese version of the SSW Test. Results revealed that, collectively, these subjects were mostly males, in elementary school, referring speech, reading and writing difficulties, and not presenting neurological disorders. They also presented a decoding-type auditory processing disorder of mild/moderate severity. Error and performance profiles were characterized by multivariate statistics.

Responses of 122 children were obtained on two measures of central auditory processing to establish normative data. Children aged 6.5 through 12.5 years were tested for humming and tapping responses to the Pitch Pattern Sequence Test (PPST) and the two- and four-digit Dichotic Digit Tests (DDT). Children between ages 6.5 and 9.5 years showed progressively better scores on the tapping response of the PPST and on the four-digit DDT. Children above 9.5 years of age demonstrated adult-like responses on both tests. No differences were demonstrated in performance of children aged 6.5 through 12.5 years on the two-digit DDT or on the humming response of the PPST.