Membrane Compliance Research Articles

Classification of tympanogram in children with hearing impairment (author's transl)

Tympanometry using Danplex ZA-20 with a probe-tone of 220Hz was performed on the total of 1470 ears with normal hearing and various kinds of hearing impairment. The subjects ranged in age from 2 to 15 years. Nine tympanic patterns from type I to IX were classified based upon tympanic membrane compliance, peak pressure and shape of tympanogram. The classification of tympanogram adopted in this study was almost similar to the one described by Jerger et al. in 1972 : Type 1 corresponded to type A of Jerger, tye II to tye AD, type III to type As, typ IV and type V to type C, and type VIII to type B. However, type VI and type VII were characterized by great tympanic membrane compliance, displacement of the peak toward the side of high negative pressure and a sharp peak at the point of maximum amplitude. These types did not correspond to any of Jerger's classification and the others. The characteristic patterns of type VI and type VII have been frequently found clinically among patients with flaccid tympanic membrane, and the resolving stage of fluid in the middle ear. Type IX was an unusual pattern which did not apparently fit into any of the above classifications. Tympanometry is particularly useful in a pediatric population were middle ear disease is so frequently encountered. Nevertheless, peak pressure value and tympanic membrane compliance value were not necessarily a reliable indicator for differentiation of normal middle ears and pathological middle ears from each other. The sharp of maximum peak in compliance as a function of the pressure must also be evaluated

Tympanometric Detection of Middle Ear Effusion in Infants and Young Children

Tympanometry, a test of middle ear status new to clinical pediatrics, was carried out on 280 subjects, 10 days through 5 years of age. The tympanograms obtained were compared with otoscopic findings and, in 107 of the subjects, with findings at myringotomy. Seven distinct tympanometric curve types were identified and defined, based on their degree of correlation with the presence or absence of middle ear effusion. In subjects 7 months of age and older, curves suggesting normal (high) tympanic membrane compliance in combination with atmospheric or near-atmospheric middle ear air pressure were rarely associated with effusion. Conversely, curves suggesting low tympanic membrane compliance were highly correlated with the presence of effusion. Curves suggesting intermediate compliance or reduced middle ear air pressure were also correlated with effusion, but the degree of correlation was dependent on the shape of the curve. In infants less than 7 months of age, many of the ears with effusion had "normal" tympanograms, presumably because external auditory canal walls in such infants tend to be highly distensible. Tympanometry is a simple, rapid, atraumatic, valid, and objective test, easily administered by paraprofessional personnel. Its use can result in improved detection of middle ear effusion and other middle ear abnormalities, and also appears to promote improvement in diagnostic acumen.

Acoustic impedance measurement in the otological assessment of multiply handicapped children.

This survey investigated the use of acoustic impedance measurement on a population of multiply handicapped children and correlated the results with otoscopy. Thirty-one children were tested with an impedance meter studying tympanometry, tympanic membrane compliance, and acoustic reflex. Otoscopic examination was also scheduled for each child. The results show that 42% of children tested had some kind of middle-ear problem, mostly unrecognized at the time of this survey. There was 100% agreement between impedance and otoscopic findings. Apparently impedance audiometry can be useful for identifying middle-ear disorders in children who cannot be tested by traditional audiometric methods.

Studies in tympanometry: validation of the present technique for determining intra-tympanic pressures through the intact eardrum.

AbstractA simple technique designed to relate controlled changes in middle ear pressures brought about in the pressure chamber with simultaneously measured tympanometric recordings was used to validate the electroacoustic impedance assessment of intratympanic air pressures in human beings.The data obtained showed the absolute and tympanometric results to be in close approximation. Tympanometry in its capacity of evaluating Eustachian tube functions, was classified into two versions: the static type, which records the consequent results of Eustachian tube functions or malfunction, together with a graphic estimation of the overall tympanic membrane compliance; and the dynamic type, that actually records and assesses Eustachian functions quantitatively. The contribution of this work toward further understanding and usage of tympanometry in clinical practice is briefly discussed in view of the proven validity and reliability of the test.

Audiometry and tympanometry in relation to middle ear effusions in children.

AbstractIn a group of 84 children with concurrent or recent middle ear disease, tympanometry and air‐conduction audiometry were compared in their ability to predict whether or not middle ear effusion was present. In addition, in children with effusions, correlations were sought between audiometric and tympanometric measurements, and the viscosity of liquids found at myringotomy.The clinical descriptions of effusions matched, in general, measurements of their viscosity.Effusions were found at myringotomy almost as often in ears with average air‐conduction thresholds below 25 db as in those with higher thresholds; in both groups an appreciable proportion of the effusions was of high viscosity.Tympanometric patterns, representing tympanic membrane compliance and middle ear air pressure, were of five general types. Effusions were found at myringotomy in most of the ears with low tympanic membrane compliance, but were not found when both tympanic membrane compliance and middle ear air pressure were normal.Sixteen ears with average air‐conduction thresholds below 25 db, but found to contain effusions at myringotomy, also had received pre‐operative tympanometry: in each instance tympanic membrane compliance had been abnormally low.The existence of negative middle ear air pressure suggests the possibility of Eustachian tubal obstruction, but the definition and conditions of abnormal levels in children remain to be established. Children with high negative middle ear air pressure should probably be considered at otologic risk.Tympanometry appears to be a reliable method for detecting the presence of middle ear effusion in children, and, therefore, should prove valuable for screening.

Liquefaction And DynamicProperties Of Gravelly Soils

Liquefaction of gravelly soil has received much attention in recent years as several case histories have been reported where gravel and gravelly soil has liquefied. As a result, much research has been focused on assessing the liquefaction potential of gravelly soils both in situ and in the laboratory. Laboratory liquefaction assessment typically includes performing undrained, cyclic triaxial tests to determine liquefaction resistance and dynamic material properties. However, the potentially adverse effects of membrane penetration and compliance must be considered. Membrane compliance may result in pore fluid redistribution, soil densification, and increased liquefaction resistance in the undrained triaxial test, making it difficult to properly evaluate the performance of the prototype material in situ. This paper presents results of undrained, cyclic triaxial tests performed on gravel specimens and sluiced gravel specimens. This paper will show the corrected cyclic strength of gravel specimens to be as low as 60% to 70% of the uncorrected strength. Increases in gravel specimen density of up to 20 percentage points or more due to membrane compliance are also documented. The bases for these determinations are presented in this paper.