Standard and multifrequency tympanometry in normal and otosclerotic ears

OBJECTIVES: The primary goal of this study was to evaluate alternative tympanometric parameters for distinguishing normal middle ears from ears with otosclerosis. A secondary goal was to provide guidelines and normative data for interpreting multifrequency tympanometry obtained using the Virtual 310 immittance system. DESIGN: Nine tympanometric measures were examined in 68 normal ears and 14 ears with surgically confirmed otosclerosis. No subjects in either group had a history of head trauma or otoscopic evidence of eardrum abnormalities. 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 degrees (F45 degrees), were derived from multifrequency tympanometry. RESULTS: Differences between normal and otosclerotic ears were statistically significant only for resonant frequency and F45 degrees. Group differences in resonant frequency were larger when estimated using positive tail, rather than negative tail, compensation. Group differences in both resonant frequency and F45 degrees were larger when estimated from sweep frequency (SF), rather than sweep pressure, tympanograms. Test performance analysis and patterns of individual test performance point to two independent signs of otosclerosis in the patient group; 1) an increase in the stiffness of the middle ear, best indexed by F45 degrees derived from SF recordings, and 2) a change in the dynamic response of the tympanic membrane/middle ear system to changes in ear canal pressure, best indexed by tympanometric width. Most patients were correctly identified by only one of these two signs. Thus, optimal test performance was achieved by combining F45 degrees derived from SF recordings and tympanometric width. CONCLUSIONS: The findings confirm the advantage of multifrequency tympanometry over standard low-frequency tympanometry in differentiating otosclerotic and normal ears. Recommendations for interpreting resonant frequency and F45 degrees measures obtained using the Virtual Immittance system are also provided. In addition, the relationship among different tympanometric measures suggests a general strategy for combining tympanometric measures to improve the identification of otosclerosis.     

Multifrequency tympanometry in chinchillas

Multifrequency tympanometry (MFT), using probe frequencies ranging from 226-2,000 Hz, was performed on normal chinchillas to obtain normative data against which to compare results from animals with middle ear pathology. A series of validating experiments was conducted to determine the effects of anatomical alterations of the middle ear on MFT. These included artificially extending the ear canal, opening the bulla, injecting saline into the middle ear, and disrupting the ossicular chain. The results indicate that MFT characteristics of chinchilla ears are qualitatively similar to those observed in normal humans and patients with middle ear disease, and MFT provides information that is not available from the 226-Hz tympanogram.     

Morphologic changes in arterial grafts in rabbit ears

The morphology of auto- and allografted segments of rabbit central ear arteries was studied at various times after grafting. Autografts showed thrombosis only in the immediate postoperative period. Autografts developed intimal thickenings whose cellular elements at all stages were almost exclusively myointimal in type. Their medial smooth muscle cells were viable at all stages. Allografts frequently thrombosed within 8 weeks of grafting. Intimal thickenings that developed in the first 6 weeks in allografts mainly contained infiltrating hematogenous cells with few myointimal cells. Immune cells infiltrated all of the layers of allograft walls, and the smooth muscle cells of their medias showed increasingly severe degeneration and by 8 weeks had completely disappeared. In long established allografts, the intima was extremely thick and contained myointimal cells and fibrous tissue. Their medias were fibrosed. In long standing allografts, immune cell infiltration was no longer present. The thrombosis of allografted arteries that occurred within 8 weeks of grafting was related to immunologic events observed within the vessel grafts. Differences between myointimal cells and smooth muscle cells with regard to their morphology and orientation were identified. A possible origin of myointimal cells from endothelial cells is suggested.     

Blepharophimosis with associated cup-lop ears

Blepharophimosis is a rare congenital triad consisting of epicanthus inversus, blepharoptosis, and a wider than normal intercanthal distance. Attention has recently been drawn to abnormalities of the eyebrow and the poorly developed nasal bridge. I record 9 cases of blepharophimosis associated with cup-lop ears seen over the last 15 years. These include a father and his 4 children.     

学前教师资格准入制度的问题与建议

学前教育是影响人一生发展的重要阶段,学前教师是影响学前教育发展的重要因素.目前,我国学前教师的师资质量不高,尤其在学前教师资格准人制度方面还存在教师资格证书终身制、入职门槛偏低、教师无资格证上岗、教师资格准入人认定内容缺失等问题,都要亟待解决.     

Jackrabbit ears: surface temperatures and vascular responses

Blood flow to the ear pinnae is curtailed at ambient temperatures of between 1.4 degrees and 24 degrees C, which minimizes heat loss across the pinnae and allows the surfaces of erect pinnae to approach ambient temperature. The pinnae are warmed by steady or pulsatile vasodilation in some animals when the ambient temperature is between 1 degree and 9 degrees C below body temperature, a response favoring heat loss. When ambient temperature exceeds body temperature by 4 degrees to 5 degrees C, the pinnae are circulated with blood cooler than ambient temperature; this response favors heat influx.     

Transient Modeling of Arbitrary Pipe Networks by a Laplace-Domain Admittance Matrix

An alternative to the modeling of the transient behavior of pipeline systems in the time-domain is to model these systems in the frequency-domain using Laplace transform techniques. Despite the ability of current methods to deal with many different hydraulic element types, a limitation with almost all frequency-domain methods for pipeline networks is that they are only able to deal with systems of a certain class of configuration, namely, networks not containing second-order loops. This paper addresses this limitation by utilizing graph theoretic concepts to derive a Laplace-domain network admittance matrix relating the nodal variables of pressure and demand for a network comprised of pipes, junctions, and reservoirs. The adopted framework allows complete flexibility with regard to the topological structure of a network and, as such, it provides an extremely useful general basis for modeling the frequency-domain behavior of pipe networks. Numerical examples are given for a 7- and 51-pipe network, demonstrating the utility of the method.     

Auditory-evoked brainstem responses elicited by maximum-length sequences in normal and sensorineural ears

Auditory brainstem responses (ABRs) were recorded using pseudo-random pulse trains called maximum-length sequences (MLSs), which allow high stimulus rates and simultaneous recording from both ears, and were compared to ABRs obtained by conventional averaging. In normally hearing subjects, ABRs by MLSs produced the same waves as conventional ABRs, although wave latencies increased and amplitudes decreased. In normal as in sensorineural ears, MLS-ABR thresholds were similar to conventional ABR thresholds (except when binaural recordings were made) and were correlated with high-frequency audiometric thresholds. Binaural MLS-ABR recordings represent the individual response of each ear, as shown by recordings of monaurally deaf subjects.     

Frequency-Domain Modeling of Transients in Pipe Networks with Compound Nodes Using a Laplace-Domain Admittance Matrix

An alternative to modeling the transient behavior of pipeline systems in the time domain is to model these systems in the frequency domain using Laplace transform techniques. A limitation with traditional frequency-domain pipeline models is that they are only able to deal with systems of a limited class of configuration. Despite the development of a number of recent Laplace-domain network models for arbitrarily configured systems, the current formulations are designed for systems comprised only of pipes and simple node types such as reservoirs and junctions. This paper presents a significant generalization of existing network models by proposing a framework that allows not only complete flexibility with regard to the topological structure of a network, but also, encompasses nodes with dynamic components of a more general class (such as air vessels, valves, and capacitance elements). This generalization is achieved through a novel decomposition of the nodal dynamics for inclusion into a Laplace-domain network admittance matrix. A symbolic example is given demonstrating the development of the network admittance matrix and numerical examples are given comparing the proposed method to the method of characteristics for 11-pipe and 51-pipe networks.     

The octave illusion revisited: Suppression or fusion between ears?

The octave illusion occurs when each ear receives a sequence of tones alternating by 1 octave but with the high and low tones in different ears. Most listeners perceive these stimuli as a high pitch in one ear alternating with a low pitch in the other ear. D. Deutsch and P. L. Roll (1976) interpreted this phenomenon as evidence for a what-where division of auditory processing caused by sequential interactions between the tones. They argued that the pitch follows the frequency presented to the dominant ear but is lateralized toward the higher frequency component. This model was examined in 4 experiments. Results indicate that the perceived pitch approximates the fundamental frequency and that the illusion does not depend on sequential interactions. The octave illusion may arise from an interaction between dichotic fusion and binaural diplacusis rather than from suppression as proposed by Deutsch. (PsycINFO Database Record (c) 2010 APA, all rights reserved)