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Bone Conduction (bone + conduction)
Selected AbstractsEvolution of the middle ear apparatus in talpid molesJOURNAL OF MORPHOLOGY, Issue 6 2006Matthew J. Mason Abstract The middle ear structures of eight species of mole in the family Talpidae (Mammalia: Eulipotyphla) were studied under light and electron microscopy. Neurotrichus, Parascalops, and Condylura have a simple middle ear cavity with a loose ectotympanic bone, ossicles of a "microtype" morphology, and they retain a small tensor tympani muscle. These characteristics are ancestral for talpid moles. Talpa, Scalopus, Scapanus, and Parascaptor species, on the other hand, have a looser articulation between malleus and ectotympanic bone and a reduced or absent orbicular apophysis. These species lack a tensor tympani muscle, possess complete bullae, and extensions of the middle ear cavity pneumatize the surrounding basicranial bones. The two middle ear cavities communicate in Talpa, Scapanus, and Parascaptor species. Parascaptor has a hypertrophied malleus, a feature shared with Scaptochirus but not found in any other talpid genus. Differences in middle ear morphology within members of the Talpidae are correlated with lifestyle. The species with middle ears closer to the ancestral type spend more time above ground, where they will be exposed to high-frequency sound: their middle ears appear suited for transmission of high frequencies. The species with derived middle ear morphologies are more exclusively subterranean. Some of the derived features of their middle ears potentially improve low-frequency hearing, while others may reduce the transmission of bone-conducted noise. By contrast, the unusual middle ear apparatus of Parascaptor, which exhibits striking similarities to that of golden moles, probably augments seismic sensitivity by inertial bone conduction. J. Morphol. © 2006 Wiley-Liss, Inc. [source] Functional morphology of the middle ear in Chlorotalpa golden moles (mammalia, Chrysochloridae): Predictions from three modelsJOURNAL OF MORPHOLOGY, Issue 2 2004Matthew J. Mason Abstract The ossicular apparatus of golden moles in the genus Chlorotalpa has received comparatively little attention in the literature, although the malleus is known to be intermediate in size between the "unmodified" malleus of Amblysomus and the hypertrophied mallei found in some other golden moles. In the present study, the middle ear structures of three Chlorotalpa species (C. duthieae, C. sclateri, and C. arendsi) are described. Measurements of middle ear structures were applied into three existing models of middle ear function. The predictions from the models suggest that the airborne hearing of Chlorotalpa species is limited to relatively low frequencies, but the impedance transformation by the middle ear apparatus is expected to be reasonably efficient. The sensitivity of the middle ear apparatus to inertial bone conduction is intermediate between that predicted for Amblysomus and that predicted for species with hypertrophied mallei. Hearing in fossorial mammals may be limited by factors other than the middle ear apparatus: the predictions for Chlorotalpa must therefore be treated with caution. However, a consideration of the "intermediate" middle ear morphology of Chlorotalpa species sheds some light on the origin of ossicular hypertrophy in golden moles. The limited enlargement of the malleus seen in Chlorotalpa is expected to have improved seismic sensitivity by bone conduction significantly at low frequencies, while airborne hearing might not have been adversely affected. J. Morphol. 261:162,174, 2004. © 2004 Wiley-Liss, Inc. [source] Auditory function and hearing loss in children and adults with Williams syndrome: Cochlear impairment in individuals with otherwise normal hearing,AMERICAN JOURNAL OF MEDICAL GENETICS, Issue 2 2010Jeffrey A. Marler Abstract Hearing loss is common in school-age individuals with Williams syndrome (WS) and extensive in adults. Prior studies with relatively small sample sizes suggest that hearing loss in WS has an early onset and may be progressive, yet the auditory phenotype and the scope of the hearing loss have not been adequately characterized. We used standard audiometric tools: Otoscopy, tympanometry, air-conduction (bone conduction when available) behavioral testing, and distortion product otoacoustic emissions (DPOAEs) to measure hearing sensitivity and outer hair cell function. We tested 81 individuals with WS aged 5.33,59.50 years. Sixty-three percent of the school-age and 92% of the adult participants had mild to moderately-severe hearing loss. The hearing loss in at least 50% was sensorineural. DPOAE testing corroborated behavioral results. Strikingly, 12 of 14 participants with hearing within normal limits bilaterally had 4,000-Hz DPOAE input/output (DPOAE IO) functions indicative of outer hair cell damage and impaired cochlear compression. Our results indicate that hearing loss is very common in WS. Furthermore, individuals with WS who have "normal" hearing as defined by behavioral thresholds may actually have sub-clinical impairments or undetected cochlear pathology. Our findings suggest outer hair cell dysfunction in otherwise normal hearing individuals. The DPOAE IO in this same group revealed growth functions typically seen in groups with noise-induced damage. Given this pattern of findings, individuals with WS may be at increased risk of noise-induced hearing loss. Recommendations regarding audiological testing for individuals with WS and accommodations for these individuals in both academic and nonacademic settings are provided. © 2010 Wiley-Liss, Inc. [source] Does Pregnancy Affect Otosclerosis?,THE LARYNGOSCOPE, Issue 10 2005William H. Lippy MD Abstract Objective: To evaluate the effect of pregnancy on the hearing of women with otosclerosis. Study Design: A retrospective study of women who had undergone stapedectomy. The women were equally divided into two groups: one group with children and a control group without children. Air and bone conduction, as well as discrimination, were measured before and after stapedectomy in both groups. Patients: Ninety-four women (47 with children and 47 without) were evaluated. Because many of the women had bilateral otosclerosis, the total number of ears studied was 128. Results: Mean pure tone air and bone conduction thresholds were not worse in women with children versus those women without children. In fact, mean pre- and postoperative pure tone air and bone conduction thresholds from 500 Hz through 4,000 Hz in women with children were slightly but significantly better than women without children. There was no difference in discrimination scores between groups. Within the group with children, no significant correlation was found between number of children and hearing loss. Also, no correlation was found between breastfeeding and the amount of hearing loss. Conclusion: We found no adverse effect on hearing in otosclerotic women who had children compared with women without children. Even with increasing numbers of pregnancies, no deleterious impact was noted. Air conduction, bone conduction, and discrimination were not worse in women with children versus childless women. No significant correlation was found between the number of children and hearing loss, and neither did breastfeeding affect the amount of hearing loss. [source] | ||||||||||