Biomedical subjects

Hasso von Wedel

Publications and source records attributed to Hasso von Wedel.

8 recordsLinked to original sources

PubMed2006

Prevalence of auditory neuropathy/synaptopathy in a population of children with profound hearing loss.

OBJECTIVE: To examine the prevalence of auditory neuropathy/synaptopathy (AN/AS) in a cohort of children with profound hearing loss. METHODS: From 1997 until 2004, 5190 children, aged 1-15 years, whose hearing ability was uncertain or who had risk factors for hearing impairment were investigated with subjective and objective hearing tests. Three thousand four hundred and fifteen from these children were screened for AN/AS using pure-tone audiometry, impedance measurement, transient evoked otoacoustic emissions (TEOAE) and click-evoked auditory brainstem responses (ABR). RESULTS: From 3415 patients who participated in an ABR and TEOAE assessment, 379 children showed absent or elevated (> or = 80 dB nHL) ABR thresholds. Within this group we found 32 cases with evidence of AN/AS via visible TEOAE and/or cochlear microphonics (CM) coupled with absent ABR. In the remaining 3036 children, AN/AS, could be ruled out by means of detectable ABR-thresholds and coherent findings in pure-tone audiometry and TEOAE assessment. This results in a prevalence of AN/AS of 0.94% within the group at risk for hearing loss, compared to 8.44% among profoundly hearing impaired children. CONCLUSION: This study shows that AN/AS is a common finding in the population of hearing impaired infants. In the majority of our AN/AS children (50%, n=16), an early audiological diagnosis was made under the age of 12 months. Therefore, clinicians and other health care professionals should generally be sensitised for AN/AS in infants, so that an appropriate treatment can promptly be initiated. Further research on clinical and pathophysiological aspects is necessary to better identify and manage patients suffering from AN/AS.

Acoustic Impedance Tests↗

PubMed2006

Influence of dynamic compression on directional hearing in the horizontal plane.

OBJECTIVE: The purpose of this study was to assess the influence of dynamic compression on directional hearing in the frontal horizontal plane. DESIGN: Compression schemes with various compression ratios and attack times were created by using a digital signal processor. The influence of compression on isolated interaural level differences (ILDs) and interaural time differences (ITDs) was examined in discrimination experiments. The combination of ILDs and ITDs was investigated with measurements of localization based on head-related transfer functions. Five normal listeners and seven hearing-impaired subjects participated in the study. RESULTS: Dynamic compression revealed substantial effects on discrimination of ILDs but not on ITDs. With higher compression ratios and shorter attack times, just-noticeable differences for ILDs increased. Lateralization via head-related transfer functions was predominantly affected by compression in the higher frequency range because for lower frequencies, interaural time cues dominate over interaural level cues. The effect of compression was similar for normal and hearing-impaired listeners, but the latter performed worse on almost all tasks, especially with ITD discrimination at 4000 Hz. CONCLUSIONS: The influence of compression ratio and attack time could be shown for ILDs, but the effect was rather small, at least for the low compression ratios commonly used in hearing aids. The influence further decreased when attack time was prolonged. The dramatic impairment of the discrimination of ITDs with the hearing-impaired subjects in the high-frequency range suggests that they primarily rely on ILD cues.

Acoustic Stimulation↗

PubMed2004

Detecting components of hearing aid fitting using a self-assessment-inventory.

The evaluation of hearing-aid fitting includes numerous assessments such as electro- and psychoacoustic tests. The subjective estimation of the hearing aid user can be elicited with self-assessment inventories encompassing various parameters, e.g., benefit, satisfaction and usage. A questionnaire comprising 11 domains (disability, handicap, frequency and significance of the listening situation, importance of the hearing aid, expectation, demand, aided performance, benefit, satisfaction and usage) within three different conditions (speech in quiet and in noise and listening to sounds) was used to detect components underlying hearing aid fitting. The data show a three-factor structure (situation-, restriction- and aid-related variables) independent from the conditions. Usage depends on all of the three factors. Disability and handicap reveal the highest values for speech in noise, whereas the aid-related factor shows the lowest values for this condition. Global satisfaction with the hearing aid is significantly correlated with the aid-related factor, but independent from the restriction of hearing. The aid-related factor is positively influenced by the amount of social activity because more active persons report higher benefit and satisfaction for all listening conditions. Age does not exhibit a significant relationship to one of the components. Basically, all correlation coefficients are only intermediate, revealing that inter-individual differences of the patients are rather high. The data indicate that extra-audiological factors might also play an important role in the success of hearing aid fitting.

Adolescent↗

PubMed2004

Psychometric evaluation of children with suspected auditory processing disorders (APDs) using a parent-answered survey.

Difficulty with auditory processing in children is of increasing interest but is the subject of some controversy in the literature This paper describes a psychometric evaluation of differences between children with suspected auditory processing disorders (APDs) and a control group, using a parent-answered questionnaire. The questionnaire comprised 51 items associated with auditory processing as well as speech/language- and behaviour-related areas. It was found that most of the items separated significantly (p<0.01) between the children with suspected APDs and the control group. A factor analysis identified seven components (speech understanding in demanding situations, speech/language abilities, general behavioural issues, reactions to questions and demands, discrimination of speech sounds, musical cues, loudness perception) underlying the contrasts between the two study populations. The examination might serve as a basis for the development of an APD-related questionnaire. However, the validity of such a questionnaire is questionable at present, since APD is not very well specified, and standardized diagnostic tests are lacking.

Auditory Perceptual Disorders↗

PubMed2003

Demands on hearing aid features--special signal processing for elderly users?

Age-related effects on several parameters of hearing aid provision, comprising the importance of various hearing aid attributes, the main reason for dissatisfaction, and a measure for aided performance, were examined. When comparing two subgroups of younger and elderly hearing aid users, a significant difference occurred for the importance of the attribute 'handling', whereas all other features examined showed only differences in trends. The question posed for the main reason for dissatisfaction with the hearing aids revealed no significant contrasts. Problems with the instruments in several listening situations were investigated by means of the Gothenburg Profile. Items related to communication in groups showed significant differences between younger and older subjects, but only non-significant contrasts remained when the mean hearing losses of the two subgroups were properly matched. Based on the data presented, some age-related concerns should be taken into account in hearing-aid provision for elderly users, but special signal processing does not seem to be necessary.

Adolescent↗

PubMed2002

Identifying the needs of elderly, hearing-impaired persons: the importance and utility of hearing aid attributes.

Older patients represent the majority of hearing-aid users. The needs of elderly, hearing-impaired subjects are not entirely identified. The present study aims to determine the importance of fundamental hearing-aid attributes and to elicit the utility of associated hypothetical hearing aids for older patients. This was achieved using a questionnaire-based conjoint analysis--a decompositional approach to preference measurement offering a realistic study design. A random sample of 200 experienced hearing-aid users participated in the study. Though three out of the six examined attributes revealed age-related dependencies, the only significant effect was found for the attribute "handling", which was considerably more important for older than younger hearing-aid users. A trend of decreasing importance of speech intelligibility in noise and increasing significance of speech in quiet was observed for subjects older than 70 years. In general, the utility of various hypothetical hearing aids was similar for older and younger subjects. Apart from the attribute "handling", older and younger subjects have comparable needs regarding hearing-aid features. On the basis of the examined attributes, there is no requirement for hearing aids designed specifically for elderly hearing-aid users, provided that ergonomic features are considered and the benefits of modern technology are made fully available for older patients.

Age Factors↗

PubMed2002

Determining the importance of fundamental hearing aid attributes.

OBJECTIVE: To determine the importance of fundamental hearing aid attributes and to elicit measures of satisfaction and dissatisfaction. STUDY DESIGN: A prospective study based on a survey using a decompositional approach of preference measurement (conjoint analysis). SETTING: Ear, nose, and throat university hospitals in Cologne and Giessen; various branches of hearing aid dispensers. PATIENTS: A random sample of 175 experienced hearing aid users aged 20 to 91 years (mean age, 61 yr) recruited at two different sites. MAIN OUTCOME MEASURE: Relative importance of different hearing aid attributes, satisfaction and dissatisfaction with hearing aid attributes. RESULTS: Of the six fundamental hearing aid attributes assessed by the hearing aid users, the two features concerning speech perception attained the highest relative importance (25% speech in quiet, 27% speech in noise). The remaining four attributes (sound quality, handling, feedback, localization) had significantly lower values in a narrow range of 10 to 12%. Comparison of different subgroups of hearing aid wearers based on sociodemographic and user-specific data revealed a large interindividual scatter of the preferences for the attributes. A similar examination with 25 clinicians revealed overestimation of the importance of the attributes commonly associated with problems. Moreover, examination of satisfaction showed that speech in noise was the most frequent source of dissatisfaction (30% of all statements), whereas the subjects were satisfied with speech in quiet. CONCLUSIONS: The results emphasize the high importance of attributes related to speech perception. Speech discrimination in noise was the most important but also the most frequent source of negative statements. This attribute will be the outstanding parameter of future developments. Appropriate handling becomes an important factor for elderly subjects. However, because of the large interindividual scatter of data, the preferences of different hearing aid users were hardly predictable, giving evidence of multifactorial influences.

Adolescent↗

PubMedDate not supplied

Modeling relationships between various domains of hearing aid provision.

Various inventories have been developed to quantify the success of hearing aid provision. Though numerous parameters including initial measures (hearing disability, handicap) or 'outcome measures' (e.g. benefit, satisfaction and usage) are recorded, relationships and interactions among them are still unclear. A study applying a questionnaire addressing 11 domains relevant to amplification was conducted in order to generate different psychometric models with the AMOS software package for structural equation modeling. The models expose easily interpretable interactions and are helpful in understanding effects occurring with commonly used outcome measures: benefit reflects the difference between the aided and unaided condition but additionally comprises the importance of the hearing aid within a specific situation. Satisfaction is highly reliant on benefit. Usage is strongly dependent on the severity of hearing problems and therefore not appropriate in assessing the success of amplification. Moreover, the models help to predict the outcome of clinically used inventories (i.e. the Glasgow Hearing Aid Benefit Profile).

Adolescent↗