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Thesis (Ph.D.)--Indiana University, Dept. of Speech and Hearing, 2009. / Title from PDF t.p. (viewed on Feb. 10, 2010). Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3401. Adviser: Larry E. Humes.

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Introduction: Current newborn hearing screening include testing with otoacoustic emission and automated auditory brainstem response. Unfortunately, both tests are affected by the presence of material in the ear canal and middle ear such as vernix, meconium and amniotic fluid. The primary objective of this study was to perform wideband measurements and otoscopy on newborns in order to determine whether occlusion of the ear canal affects the wideband measurements. A secondary objective was to compare the wideband measurements obtained after birth to those taken at 14 to 28 days later. A third objective was to obtain additional wideband normative data in newborns. Materials and Methods: Newborns from a well-baby nursery were enrolled. Wideband measurements under both ambient and pressurized conditions and otoscopy were done immediately after the hearing screening and between 14 and 28 days later. Occlusion of the ear canal as seen on otoscopy was described on a scale of 0 to 100% in increments of 10.Results: A total of 156 babies were enrolled. On the first measurement, a statistically significant difference in reflectance was found between 0-70% and 80-100% occlusion groups and between 6 groups of frequencies between 250 Hz and 8 kHz. There was no significant difference in reflectance between the right and the left ears. A comparison of reflectance under pressurised conditions between the first and second measurements has shown a higher reflectance at the negative pressure region during the first few days of life. Conclusion: Significant increase in reflectance occurs when 70% to 80% of the ear-canal diameter is occluded. A trend of higher reflectance appears to be present when the canal is pressurized to negative values. A comparison of reflectance between the present study and previous studies is given. / Introduction: Le dépistage néonatal de la surdité actuel inclut l'évaluation d'émissions oto-acoustiques automatisées et la réponse évoquée auditive du tronc cérébral. Malheureusement, les résultats de ces tests peuvent être affectés par la présence de matériaux transitoires dans le conduit auditif externe et l'oreille moyenne comme par exemple le vernix, le méconium et le liquide amniotique. L'objectif primaire de cette étude était d'effectuer des mesures de réflectance à large bande et un examen otoscopique sur les nouveau-nés afin de déterminer si l'occlusion du conduit auditif externe affecte les mesures à large bande. Un objectif secondaire était de comparer les mesures après la naissance à celles obtenues 14 à 28 jours plus tard. Le troisième objectif était d'obtenir des données normatives supplémentaires. Matériels et méthodes: De nouveau-nés d'une pouponnière de bébés en santé ont été inscrits. Les mesures à large bande, effectuées dans des conditions ambiantes et sous pression, et l'examen otoscopique ont été exécutés immédiatement après le dépistage de la surdité et entre 14 et 28 jours plus tard. L'occlusion du conduit auditif externe, vu par examen otoscopique, a été décrite par une échelle de 0 à 100% d'obstruction, par étapes de 10%. Résultats: Un total de 156 bébés ont été inscrits. Lors de la première mesure, une différence statistiquement significative a été observée entre les groupes 0-70% et 80-100% d'obstruction du conduit, et également entre les 6 groupes de fréquences auditives comprises entre 250 Hz et 8 kHz. Il n'y avait aucune différence significative entre l'oreille droite et la gauche. Une comparaison des résultats dans des conditions sous pression, entre la première et la deuxième mesure, a démontré un coefficient de réflectance supérieur à la zone de pression négative pendant les premiers jours de vie.Conclusion: Une augmentation significative de la réflectance se produit lorsque le conduit auditif externe est obstrué de 70% à 80%. Une tendance de réflectance plus élevée semble être présente lorsque le canal est sous pression, à des valeurs négatives. Une comparaison des résultats de cette étude et d'études antérieures est discutée.

The diagnostic utility of tympanometry with respect to distinguishing healthy and otosclerotic ears was investigated in four studies. This issue was examined with respect to alternative measures of static immittance (SI), tympanometric shape, resonant frequency (RF), and frequency corresponding to admittance phase angle of 45 degree (F45°) obtained from 68 healthy ears and 36 ears with surgically confirmed otosclerosis. Study 1 served to replicate previous findings that otosclerotic and healthy ears differ with respect to F45° and RF but not SI and TW measured at 226 Hz, thus confirming the advantage of multifrequency measures over standard low frequency tympanometric measures in differentiating healthy and otosclerotic ears. Studies 2 and 3 examined the effect of probe tone frequency on the diagnostic utility of SI and tympanometric shape. Group differences were evident for SI measured using a probe tone near the frequency corresponding to F45°, in the present study the optimal probe frequency was 630 Hz. Group differences were not evident for tympanometric width (TW) at 226 Hz, 350, and 450 Hz whereas the two groups differed in distribution of Vanhuyse patterns of 1B1G and 3B1G observed at frequencies between 800 Hz and 1250 Hz. In study 4 the diagnostic performance of five different tympanometric parameters was assessed using test performance and receiver operating characteristic (ROC) analysis. Results showed that F45° was the best single measure to distinguish healthy ears from otosclerotic ears; RF and SI measured at 630 Hz were the next best measures followed by Vanhuyse patterns; TW was the least useful measure. However, when compared using optimal decision criterion (derived from ROC analysis) differences in test performance for F45° and SI measured at 630 Hz were small suggesting that their clinical utility is comparable. Correlations and patterns of individual performance also confirm the presence of two independent signs of otoscle

Introduction: Radiotherapy can cause permanent hearing loss when the ears are included in the radiation field. To date, no treatment is available to prevent this outcome. The effects of radiation are caused by free radical formation, leading to apoptosis of the cells in the organ of Corti. Metformin has demonstrated anticancer and anti-aging properties through the regulation of reactive oxygen species production after cellular stresses.Objectives: To determine the safety and radio-protective properties of Metformin against radiation-induced cochlear damage in vivo and in vitro. Materials and Methods: For the in vitro study, cultured auditory hair cells (HEI-OC1) were exposed to different concentrations of Metformin to determine its safety. Next, cells were incubated with these concentrations and subjected to radiation. Cell viability after experiments was determined with the 3-(4, 5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay.For the in-vivo study, 15 guinea pigs were divided in two groups: drinking tap water (n=7) and drinking water containing Metformin (n=8) at a dose of 100 mg/kg/day. The ears of the animals were unilaterally irradiated for 20 days (total dose 71 Gy) and subsequently divided in four groups: Control (n=7), Irradiated (n=7), Metformin (n=8), Experimental (n=8). Distortion Products Otoacoustic Emissions (DPOAE) and Auditory Brainstem Responses (ABR) were assessed before, one week and six weeks after completion of radiotherapy.Results: Metformin was not ototoxic or radio-protective in cultured auditory hair cells. DPOAE measurements did not show hearing loss or differences between the four groups at the different time points evaluated. After 6 weeks, ABR demonstrated progressive hearing loss. Experimental ears had less hearing loss than radiated ones; however, differences were not statistically significant.Conclusion: Metformin is not ototoxic in vitro or in vivo. Metformin was not protective against radiation induced cell death in vitro. / Introduction: La radiothérapie peut provoquer une perte auditive permanente quand l'oreille est incluse dans la zone de radiation. Il n'y existe aucun traitement préventif pour cet effet néfaste. La radiation provoque la formation des radicales libres entrainant la mort de cellules dans l'organe de Corti. La Metformine, un médicament vastement utilisé dans le traitement du diabète a montré des propriétés anticancéreuses et antivieillissement par la régulation de la production d'espèces réactives de l'oxygène après le stress cellulaire. Objectifs: Déterminer l'ototoxicité et les propriétés radio-protectives de la Metformine contre l'atteinte cochléaire provoqué par radiation in vivo et in vitro.Matériaux et méthodes: Les cellules auditives cultivées (HEI-OC1) ont été exposées à différentes concentrations de Metformine pour déterminer le potentiel d'ototoxicité de ce dernier. En plus, les cellules ont été incubées avec diverses concentrations et par la suite, exposées à la radiation. La survie cellulaire a été déterminée par la méthode MTS. Quinze cochon d'Inde ont été divisés en deux groupes: buvant de l'eau potable (n=7) et buvant de l'eau contenant la Metformine (n=8) avec une dose de 100 mg /kg/jour. Les oreilles des animaux ont été irradiées unilatéralement pendant 20 jours (dose totale 71 Gy) et par conséquence ont été divisées en quatre groupes: Control (n=7), Irradiées (n=7), Metformine (n=8), Expérimentales (n=8). Les Produits de Distorsion des Émissions Otoacoustiques (PDEO) et les Réponses Auditives du Tronc Cérébral (RATC) ont été six semaines après la radiothérapie.Résultats: La Metformine n'est pas été ototoxique ou radio-protective des cellules auditives cultivées. Les PDEO test n'ont pas montré de perte auditive ou de différences entre les quatre groupes aux différents temps évaluées. Après six semaines. Les oreilles expérimentales ont eu moins de perte auditive comparées aux oreilles irradiées, néanmoins les différences n'ont pas été significatives.Conclusion: La Metformine n'est pas ototoxique in vitro ou in vivo. La Metformine n'a pas été otoprotective in vitro ou contre la perte auditive causée par radiation après un suivi de six semaines après la fin de la radiothérapie.

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<p> The goal of this study was to determine whether sequentially acquired bilateral implants provide improved speech understanding relative to performance with unilateral implants in varying sound source configurations that may more closely represent daily listening environments. Participants were divided into higher and lower performance groups based upon their best unilateral performance on monosyllabic words in quiet and asked to repeat Bamford-Kowal-Bench Speech-in-Noise (BKB-SIN) sentences in unilateral and bilateral listening conditions. The sentences were always presented from directly in front, while competing noise was presented from varying locations. Results indicated that the bilateral listening condition yielded significantly better scores compared to the unilateral listening condition across all participants, with the higher performance group's scores significantly better than for the lower performance group. Both groups had similar gains in performance. No significant differences were observed amongst sound sources, contrary to the original hypothesis. Among demographic variables, only unilateral performance on words in quiet and onset of deafness were highly correlated with bilateral performance. As the initial grouping variable addressed performance in quiet, a second analysis regrouped participants by onset of deafness (pre- vs. postlingual) This regrouping yielded even greater group differences overall, and some noise configurations were now significantly different for the postlingually deafened participants. Taken together, these results suggest that postlingually deafened participants may be able to use higher level binaural processes established prior to deafness and not available to prelingually deafened listeners.</p>

Nine tympanometric measures were examined in 68 normal ears and 14 ears with surgically confirmed otosclerosis. Two parameters, static admittance and tympanometric width, were derived from standard low frequency tympanometry and two parameters, resonant frequency and frequency corresponding to admittance phase angle of 45$ sp circ$ (F45$ sp circ),$ were derived from multifrequency, multicomponent tympanometry. The results show the advantage of multifrequency, multicomponent tympanometry over standard low frequency tympanometry in differentiating otosclerotic ears from normal ears. In particular, for identifying high impedance pathologies, the present findings support the use of sweep frequency (SF) recording for measuring resonant frequency and frequency corresponding to admittance phase angle of 45$ sp circ$ (F45$ sp circ)$ and positive tail compensation for measuring resonant frequency. The relationship among the measures obtained in this study also revealed that two distinct signs are evident in the patient group; (1) an increase in the stiffness of the middle ear best shown by F45$ sp circ$ measured using SF method, and (2) an increase in the sharpness of the tympanogram best shown by tympanometric width. The combination of F45$ sp circ$ measured using SF method and tympanometric width separated normal from otosclerotic ears better than any single measure used in this study.