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Assessment of central auditory functions: methods and applications
Linköping University, Department of Neuroscience and Locomotion, Technical Audiology. Linköping University, Faculty of Health Sciences.
2001 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Central auditory processing is complex and can not be completely evaluated by a single method. This thesis focuses on assessment of some aspects of central auditory functions by the use of dichotic speech tests, cognitive tests that tax functions important for speech processing and electrophysiological tests.

Paper A deals with the cognitive effects in dichotic speech testing in elderly hearing impaired subjects. Dichotic speech tests and cognitive tests were performed on 30 hearing impaired subjects ranging in age from 42 to 84 years. The dichotic test material consisted of digits, short sentences and consonant-vowel-syllables. The cognitive test material comprised tests for short-term memory, verbal information processing and phonological processing. Effects of age in dichotic speech tests in elderly were verified. The degree of effect was dependent upon focusing condition and test material. The 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 in the elderly was strongly connected with problems to perceive stimuli presented to the left ear.

Paper B presents a new cognitive test battery, performed in text, auditory and audiovisual modalities. The tests are sensitive for functions important for speech processing and understanding. The test battery was evaluated in four groups, differing in age and hearing status. Each group comprised twelve subjects. The effect of low-level noise on cognitive functions was investigated. The only significant result in the text modality was an age effect in speed of performance, which was also seen in the auditory and audiovisual modalities. In the auditory and audiovisual modalities effects of hearing status and modality were seen in accuracy parameters. Interaction between hearing status and modality, both in accuracy and speed of performance, shows that hearing-impaired subjects benefit more from visual cues. In noise generally poorer results were obtained, especially in the auditory modality and for the elderly, affecting both accuracy and speed. The test battery has proven to be useful in assessing the relative contribution of different input-modalities and the effect of age, hearing-impairment and visual contribution on functions important for speech processing.

Paper C describes the development of a system for recording of auditory evoked potentials. The system is built around a personal computer with a data-acquisition board with analogue input and output channels. Acoustic stimuli are presented to the test subject and responses to the acoustic stimuli are recorded in an EEG-recording system. The program is written in the graphical programming environment LabView (National Instruments). With the system it is possible to perform all clinical standard measurements. In addition, test-procedures not available in commercial auditory evoked potential systems have been developed. For the assessment of auditory discrimination a toolkit for evaluation of the mismatch negativity potential was developed and evaluated in six normal-hearing subjects.

Place, publisher, year, edition, pages
Linköping: Linköpings University Electronic Press , 2001. , 22 p.
Series
Linköping Studies in Health Sciences. Thesis, ISSN 1100-6013 ; 47Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 871
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:liu:diva-28044Local ID: 12805ISBN: 91-7219-956-3 (print)OAI: oai:DiVA.org:liu-28044DiVA: diva2:248595
Presentation
(English)
Available from: 2009-10-08 Created: 2009-10-08 Last updated: 2013-11-13
List of papers
1. Cognitive effects in dichotic speech testing in elderly persons
Open this publication in new window or tab >>Cognitive effects in dichotic speech testing in elderly persons
2001 (English)In: Ear and Hearing, ISSN 0196-0202, Vol. 22, no 2, 120-129 p.Article in journal (Refereed) Published
Abstract [en]

OBJECTIVE: To study the effect of chronologic age on central auditory functions using dichotic speech tests and to study whether and how the age effect in dichotic listening is related to cognitive ability.

DESIGN: Dichotic speech tests and cognitive tests were performed on 30 bilaterally hearing-impaired subjects, with a pure-tone average better than 50 dB HL. They were between 42 and 84 yr of age and were divided into an older and a younger group comprising 15 subjects each. The dichotic test material were digits, low-redundancy sentences and consonant-vowel syllables. The subjects reported stimuli heard in both ears (free report) or in one ear (directed report to left or right ear). The cognitive test battery comprised tests focusing on short-term memory, verbal information-processing speed and phonologic processing.

RESULTS: A decreased overall performance in all dichotic speech tests was observed in the older group. In the syllable test the older subjects showed poorer results when focusing on the stimuli heard in the left ear, as compared with when focusing on stimuli heard in the right ear, whereas the younger group showed almost equal results for left- and right ear-focusing conditions. An age effect was also seen in reaction times recorded in the cognitive tests and in the scores of the reading span test. These cognitive parameters correlate with the results of the dichotic test when focusing to the left, but not when focusing to the right in the directed report condition. In the free report condition the overall performance showed a high correlation with cognitive test parameters.

CONCLUSIONS: Effects of chronologic age in dichotic speech tests in the elderly have been verified. The degree of effect is dependent on test material, way of reporting and focusing condition. The different listening tasks in dichotic tests put different demands on cognitive ability shown by a varying degree of correlations between cognitive function and dichotic test parameters. Also, the results indicate a strong connection between age-related cognitive decline in the elderly and problems to perceive stimuli presented to the left ear.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-13584 (URN)10.1097/00003446-200104000-00005 (DOI)
Available from: 2005-05-28 Created: 2005-05-28 Last updated: 2016-03-14
2. Evaluation of a cognitive test battery in young and elderly normal-hearing and hearing-impaired persons
Open this publication in new window or tab >>Evaluation of a cognitive test battery in young and elderly normal-hearing and hearing-impaired persons
2001 (English)In: Journal of the American Academy of Audiology, ISSN 1050-0545, Vol. 12, no 7, 357-370 p.Article in journal (Refereed) Published
Abstract [en]

A cognitive test battery sensitive to processes important for speech understanding was developed and investigated. Test stimuli are presented as text or in an auditory or audiovisual modality. The tests investigate phonologic processing and verbal information processing. Four subject groups, young/elderly with normal-hearing and young/elderly with hearing impairment, each including 12 subjects, participated in the study. The only significant effect in the text modality was an age effect in the speed of performance, seen also in the auditory and audiovisual modalities. In the auditory and audiovisual modalities, the effects of hearing status and modality were seen in accuracy parameters. Interactions between hearing status and modality, both in accuracy and in reaction times, show that hearing-impaired subjects have difficulties without visual cues. Performing the test battery in noise made the tasks more difficult, especially in the auditory modality and for the elderly, affecting both accuracy and speed. Test-retest measurements showed learning effects and a modality-dependent variability. The test battery has proven useful in assessing the relative contribution of different input signals and the effects of age, hearing impairment, and visual contribution on functions important for speech processing.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-13585 (URN)
Available from: 2005-05-28 Created: 2005-05-28 Last updated: 2013-11-13
3. A system for recording of auditory evoked responses
Open this publication in new window or tab >>A system for recording of auditory evoked responses
2000 (English)In: Technology and Health Care, ISSN 0928-7329, Vol. 8, 315-326 p.Article in journal (Refereed) Published
Abstract [en]

A system for recording of evoked potentials from auditory stimulation was developed. The system consists of a PC equipped with an audio bandwidth board with analog input and output channels. The sound stimulus signal is generated in the computer, D/A converted, and via audio amplifier fed to earphones on the test subject. Auditory evoked potentials in response to sound stimuli are recorded via electrodes, amplified and filtered in an EEG recording system and fed to an A/D converter. The signal is analysed in the PC. The modular design of the program makes it a flexible system where stimulus and recording parameters can easily be modified and new applications can be added to standard clinical measurements.

Three applications that are not possible with commercially available systems were developed and evaluated. a) A diagnostic procedure to verify hydrops in patients with Meniere's disease. b) Intraoperative recordings of auditory evoked potentials during neurootological surgery. c) Recording of mismatch negativity (MMN) potentials in evaluation of central auditory functions.

Keyword
evoked potentials, evoked potentials, evoked potentials, evoked potentials, evoked potentials, evoked potentials, evoked potentials, evoked potentials, evoked potentials
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-27612 (URN)11258578 (PubMedID)12342 (Local ID)12342 (Archive number)12342 (OAI)
Available from: 2009-10-08 Created: 2009-10-08 Last updated: 2013-11-13

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