Biomedical subjects

M Hällgren

Publications and source records attributed to M Hällgren.

4 recordsLinked to original sources

PubMed2001

Cognitive effects in dichotic speech testing in elderly persons.

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.

Adult↗

PubMed2000

A system for recording of auditory evoked responses.

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.

Audiometry, Evoked Response↗

PubMed1998

Dichotic speech tests.

When central auditory dysfunction is present, ability to understand speech in difficult listening situations can be affected. To study this phenomenon, dichotic speech tests were performed with test material in the Swedish language. Digits, spondees, sentences and consonant-vowel syllables were used as stimuli and the reporting was free or directed. The test material was recorded on CD. The study includes a normal group of 30 people in three different age categories; 11 years, 23-27 years and 67-70 years. It also includes two different groups of subjects with suspected central auditory lesions; 11 children with reading and writing difficulties and 4 adults earlier exposed to organic solvents. The results from the normal group do not show any differences in performance due to age. The children with reading and writing difficulties show a significant deviation for one test with digits and one test with syllables. Three of the four adults exposed to solvents show a significant deviation from the normal group.

Adult↗

PubMedDate not supplied

Evaluation of a cognitive test battery in young and elderly normal-hearing and hearing-impaired persons.

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.

Adult↗