Hasso von Wedel

The relationship between pre-fitting expectations and willingness to use hearing aids.

Hearing-aid use in the elderly population is problematic since not all people who would benefit from hearing aids actually obtain one. In this study, the relationship between pre-fitting expectations and willingness to use hearing aids is addressed. One hundred adult hearing aid candidates (mean age 68.6 years) were randomly recruited from eight different private ENT practices. The subjects completed a questionnaire comprising a number of different aspects of expectation and some additional variables potentially influencing willingness to use hearing aids. Based on the outcome of the questionnaire a linear regression model predicting motivation to use hearing aids was calculated and evaluated. Among the 11 parameters evaluated three contributed significantly to the model of willingness. The three predictor variables were expectations towards improvement of quality of life, stigmatization, and self-rated hearing ability. They accounted for about 55% of the variability in the data for willingness. Examination of a sub-sample three months after the survey had taken place revealed a distinct relationship between willingness and the decision to obtain or decline hearing aids. In conclusion, the results strongly encourage supporting positive expectations in order to motivate individuals with hearing impairment to use hearing systems.

Risk Factors for Auditory Neuropathy/Auditory Synaptopathy

Aims: It was the aim of this study to describe risk factors in auditory neuropathy/auditory synaptopathy (AN/AS). Methods: Between 1997 and 2005, we diagnosed 37 children with AN/AS. They underwent a critical chart review for risk factors and etiological coincidences in this idiosyncratic disorder. Results: Eighteen neonates had a history of prematurity and low birth weight. Hyperbilirubinaemia was present in 13 children. Three patients had evidence of infection during pregnancy, and AN/AS was associated with complex syndromal diseases in 2 cases. A congenital, familial pattern was seen in 2 siblings. Seven patients had idiopathic AN/AS. Conclusion: Rather than being a single etiological entity, AN/AS comprises a spectrum of risk factors and associated problems affecting the cochlea and the auditory pathway. This study shows that the majority of AN/AS in children is the result of perinatal problems and is not genetic in origin. Hyperbilirubinaemia is a common and etiologically significant finding in infants suffering from AN/AS. Thus, early hearing screening for AN/AS including transient evoked otoacoustic emissions and auditory brainstem response assessment among neonates with risk factors for AN/AS is crucial in order to better manage patients suffering from this disorder.

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.

The perception of prosody and speaker gender in normal-hearing listeners and cochlear implant recipients

The purpose of this study was to examine the effects of altering the fundamental frequency (F0) on perception of prosody and speaker gender in both normal-hearing listeners and cochlear implant (CI) recipients. Tests with natural speech and defined modifications of the F0 were performed, and the resulting changes in perception were measured. Compared to the normal-hearing listeners, most of the CI users exhibited worse outcomes, especially for sentence stress. In contrast, the speaker gender tests yielded similar results for both groups when artificially modifying the F0 contour. The results seemed to be strongly related to the duration of alterations in F0. Although the perception of prosodic cues was limited in most of the CI recipients, they showed qualitatively similar results to normal-hearing listeners in that the boundary between questions and statements and between female and male voices was comparable. A large inter-individual difference in performance was observed among the CI recipients, which could not be attributed to different processor or implant types or to other factors such as implant experience.

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.

Using conjoint analysis to examine the importance of hearing aid attributes.

Objective To introduce conjoint analysis (CA) as a method to explain choice decisions of hearing aid users and to measure the contributions of different hearing aid attributes involved. Design The study was conducted using CA, a method that is well established in marketing, but has not been used for hearing aid research. CA examines the contributions (importance) various attributes make to overall preference judgements. It is based on the premises that objects (i.e., hearing aids) can be described as different combinations of several attributes. The relative importance of the attributes is estimated from integral judgements of hypothetical hearing aids. The advantages of CA are a more realistic presentation of complete products instead of isolated attributes and the consideration of trade-offs between the features. The following attributes selected from 12 features in a prestudy were included in the application: speech perception in quiet, speech perception in noise, handling, sound quality, localization, and feedback. 93 randomly chosen experienced hearing aid wearers participated in the survey. Results It was found that the attributes concerning speech perception were by far most important. Speech discrimination in quiet and in noise were almost equally significant and contributed with 56% to the preference decisions of the subjects. The remaining attributes showed values in the range of 10% to 12%. When comparing various subgroups dependent on age, sex, hearing loss, satisfaction, etc., significant differences concerning the preferences were found. Elder and female subjects attached greater importance of the attribute “handling” whereas younger patients judged “speech in noise” more important. In general, subjects with greater hearing loss considered speech intelligibility in quiet to be more important than in noisy surroundings. Moreover, sound quality seems to be a significant indicator for satisfaction with the hearing aid. Conclusions This study proposes CA as a survey technique to examine individual preferences for hearing aids. Several assumptions about the importance of hearing aid features for different groups of users could be confirmed quantitatively. Segmentation showed valid results depending on socio-demographic and user-specific parameters. The method used and the results are of interest for audiologists as well as the hearing aid industry. They provide valuable tools for future hearing aid design and should be considered in the development of self-assessment inventories.

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. Sumario Las dificultades alrededor del procesamiento auditivo en niñson de interés creciente pero también motivo de controversia en la literatura. Este trabajo describe la evaluación psicométrica de las diferencias entre niños con sospecha de APDs y un grupo control, usando un cuestionario contestado por los padres que comprende 51 puntos asociados con el procesamiento auditivo así como con áreas relacionadas de habla/lenguaje y conducta. Se encontró que en la mayoría de las áreas hay una separación significativa (p < 0.01) entre los niños con sospecha de APDs y los del grupo control. Un análisis de factores identificó siete componentes (comprensión del lenguaje en situaciones demandantes, competencia en habla/lenguaje, aspectos comportamentales generales, reacciones a preguntas y tareas, discriminación de sonidos del lenguaje, claves musicales y percepción de intensidad subjetiva) que enfatizaron los contrastes entre las dos poblaciones estudiadas. El examen puede servir como base para el desarrollo de un cuestionario relacionado con APDs. No obstante, la validez del mismo es por ahora cuestionable, porque las APDs no están bien especificadas y por la carencia de pruebas diagnósticas estandarizadas.

Age-dependence of the neural auditory thresholds of albino and pigmented guinea pigs

ZusammenfassungEine Altersabhängigkeit der neuralen Hörschwelle von Albino- und pigmentierten Meerschweinchen wurde an Hand kurzlatenter Hirnstammantworten untersucht. Für beide Gruppen konnte ein altersbedingter Hörverlust festgestellt werden. Des weiteren zeigten Albinos signifikant niedrigere Hörschwellen als pigmentierte Meerschweinchen der entsprechenden Altersgruppe. Als weiterer Unterschied zwischen beiden Gruppen fand sich bei Albinos ein um die Hälfte geringer Altershörverlust als bei pigmentierten Meerschweinchen.SummaryShort-latency brain-stem responses of albino and pigmented guinea pigs were examined for evidence of age-dependence of the auditory threshold. Both groups exhibited a loss of hearing correlated with age. Moreover, albinos had significantly lower auditory thresholds than pigmented guinea pigs of the corresponding age group. A further difference between the two groups lay in the degree of which sensitivity declined with age; hearing loss in albinos was only about half that in pigmented animals.

Hearing loss in early infancy affects maturation of the auditory pathway

The influence of early cochlear hearing loss on maturation of the auditory pathway was studied by measuring auditory brainstem responses (ABR). In a retrospective study, 85 children with normal hearing (46 males, 39 females; age range 2 months to 14 years) and 165 children with binaural cochlear hearing impairment (89 males, 76 females; age range 1 month to 16 years) were examined. A significant positive correlation (p<0.001) between the degree of hearing loss and interpeak latencies I-V (IPL(I-V)) of the ABR was observed. No significant correlation (p=0.85) was found between hearing loss and interpeak latencies I-III (IPL(I-III)). These findings can be interpreted as indicating a marked delay in maturation of higher brainstem structures due to reduced auditory input during infancy. The correlation differs notably from results of comparable studies of adults published in recent literature. This leads to the assumption that the developing human brain is particularly sensitive to auditory deprivation. Thus, our results indicate the importance of a normal acoustic environment during sensitive periods in early childhood to ensure normal hearing and speech development.

Age-related changes in the auditory evoked brainstem

ZusammenfassungZur Erfassung altersspezifischer Veränderungen peripherer Hörbahnstationen wurden akustisch evozierte Hirnstammantworten bei Meerschweinchen zweier Altersstufen untersucht. Da Angaben über Unterschiede in der Hörleistung von Albino- und pigmentierten Meerschweinchen vorliegen, wurden beide Kollektive in die Untersuchung einbezogen. Im Latenzverhalten wiesen beide Altersstufen keine Unterschiede auf; ebenso ließ sich für die Laufzeitdifferenz der einzelnen Potentiale kein Alterseinfluß feststellen. Die Amplitude der Hirnstammantworten dagegen zeigte sich bei alten Meerschweinchen für hohe Frequenzen deutlich reduziert, wobei das dynamische Verhalten der Amplitude beider Altersgruppen keine Unterschiede aufwies. Albino- und pigmentierte Meerschweinchen entsprachen sich in beiden Altersgruppen in den Größen der untersuchten Parameter. Der Einfluß des Alterungsprozesses auf die peripheren Hörbahnstationen wird auf Grund der ermittelten Ergebnisse diskutiert.SummaryThe auditory evoked brainstem responses of guinea pigs in two age groups were recorded and examined for evidence of age-dependent changes at peripheral stations in the auditory pathway. Because pigmented guinea pigs have been found to be less sensitive to sounds than albinos, both groups were included in this study. Old and young animals did not differ in response latency or in the conduction times associated with the individual potentials. By contrast, the amplitudes of the brainstem responses to high-frequency stimuli were distinctly reduced in old guinea pigs, with no difference in the dynamic of the amplitude between the two age groups. Within each age group, albino and pigmented animals resembled one another in all parameters studied. The effect of the aging process at the peripheral stations of the auditory pathway is discussed in the light of these results.