Martin Walger

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.

Plastination: a new approach to morphological research and instruction with excised larynges.

Impregnation of biologic materials with curable polymer (plastination) allows wider use of human tissue for both basic and clinical research and instruction. The aim of this study was to determine for the first time the potential of this method in the field of laryngology. A feasibility study on 54 pig larynges established a detailed methodology for larynx plastination and determined the extent of shrinkage by using computer-assisted morphometry. The process involves dehydration, saturation with an appropriate intermediate solvent, and infiltration with cured polymer in vacuo. In the main study 20 fresh, intact human larynges and 12 laryngectomy specimens were submitted to plastination. The resulting resin blocks were cut with a diamond band saw into 0.8-mm sections in the transaxial plane. The resulting specimens are dry, odorless, and durable, and do not deteriorate with time. The subtle features of soft tissue pathology are well preserved. Shrinkage of plastinated larynges is less than 10%. The complete process is accomplished within 5 weeks. Staining of sections with toluidine blue provides an enhanced contrast between different types of tissue, allowing a clear identification of tumor invasion. Plastination is considerably faster than celloidin embedding and causes minor anatomic changes. It provides durable specimens of high quality for teaching purposes. In research, it allows the investigation of all tissue components in their undisturbed context in the borderline area between gross anatomy and histology.

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.

Diagnostik und Therapie der auditorischen Synaptopathie/Neuropathie

ZusammenfassungDie audiologische Konstellation von pathologischen frühen akustisch evozierten Potenzialen (fehlend, erhöhte Schwelle und gestörte Kurvenform) trotz nachweisbarer otoakustischer Emissionen geht häufig mit einer von schlechtem Sprachverständnis geprägten Schwerhörigkeit bzw. mit Taubheit einher. Diese als auditorische Neuropathie erstbeschriebene, heterogene Erkrankungsgruppe beinhaltet peripher-auditorische Störungen der synaptischen Schallkodierung durch innere Haarzellen (Synaptopathie) und/oder der Erregungsbildung und -weiterleitung im Hörnerv (Neuropathie). Dieses Konsensuspapier gibt aktuelle Hintergrundinformationen sowie Empfehlungen zur Diagnostik und Therapie im deutschsprachigen Raum. Es nimmt dabei Bezug auf aktuelle internationale Statements.AbstractPathological auditory brainstem responses (lack of responses, elevated thresholds and perturbed waveforms) in combination with present otoacoustic emissions are typical audiometric findings in patients with a hearing impairment that particularly affects speech comprehension or complete deafness. This heterogenous group of disorders first described as “auditory neuropathy” includes dysfunction of peripheral synaptic coding of sound by inner hair cells (synaptopathy) and/or of the generation and propagation of action potentials in the auditory nerve (neuropathy). This joint statement provides prevailing background information as well as recommendations on diagnosis and treatment. The statement focuses on the handling in the german language area but also refers to current international statements.

Standardized measurements of the sound transmission of middle ear implants using a mechanical middle ear model

Abstract Several ways to evaluate the sound transmission properties of middle ear implants are now established. Besides computer-based simulations using acoustic and electrical analog circuits or finite element analysis, measurements can be performed with temporal bone preparations. Experiments with these preparations consider various anatomical properties, but a large number of parameters influence the outcome of measurements. To facilitate standardized measurements, a mechanical middle ear model was developed that allows comparison of the transfer function of middle ear implants on defined conditions. The model approximates the impedances of the tympanic membrane and inner ear with the aid of thin, flexible membranes. The implants are fit between the membranes, and displacement at an artificial stapes footplate is measured with an optical probe. Fundamental influences on the sound transmission properties of nine different middle ear implants (total ossicular replacement prostheses) were examined. Although the material and shape were different, some of the prostheses revealed very similar transfer functions. The mass of the implant showed the largest influence on sound conduction. With a higher mass, the frequency area above approximately 1 kHz was found to be significantly deteriorated. The lightest implant used was 4 mg and showed the best overall results. These findings show that middle ear prostheses should be as light as possible for optimum high-frequency transmission.

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.