Body Inversion and the Acoustic Immittance of the Ear

1974 ◽  
Vol 17 (2) ◽  
pp. 310-320 ◽  
Author(s):  
J. H. Macrae
Keyword(s):  
Middle Ear ◽  
Atmospheric Pressure ◽  
Upright Position ◽  
Air Pressure ◽  
Tone Frequency ◽  
Reactive Component ◽  
Inverted Position ◽  
External Meatus ◽  
Resistive Component ◽  
Labyrinthine Fluids

The effect of body inversion on the acoustic immittance of normal ears was investigated by means of admittance tympanometry at a probe-tone frequency of 660 Hz. In the upright position, maximum acoustic admittance at the tympanic membrane occurred when the air pressure in the external meatus was close to atmospheric pressure. In the inverted position, the admittance at the membrane was considerably reduced when the meatal air was at atmospheric pressure and maximum admittance occurred at a meatal air pressure of about 53 mm H 2 O, with the resistive component reduced and the reactive component slightly increased relative to their values in the upright position. When the middle-ear air pressure in the inverted position was equalized with the ambient atmospheric pressure, the maximum admittance at the membrane occurred at a meatal air pressure of 10–20 mm H 2 O and the reduction in conductance and slight increase in susceptance persisted. It was concluded that the effect of body inversion on the acoustic immittance of the ear is due largely to an increase in the air pressure in the middle-ear cavity (which is probably produced by an increase in the volume of the mucosa lining the cavity) and to a small extent to another overpressure which probably occurs in the labyrinthine fluids.

Effects of Body Position on the Auditory System

1972 ◽  
Vol 15 (2) ◽  
pp. 330-339 ◽  
Author(s):  
J. H. Macrae
Keyword(s):  
Hydrostatic Pressure ◽  
Tympanic Membrane ◽  
Auditory System ◽  
Middle Ear ◽  
Acoustic Impedance ◽  
Body Position ◽  
Upright Position ◽  
Tensor Tympani Muscle ◽  
Muscle Reflexes ◽  
Labyrinthine Fluids

Effects of body position on auditory threshold acuity, the acoustic impedance at the tympanic membrane, and the middle ear muscle reflexes were investigated at 150, 250, and 500 Hz. Relative to the values obtained in the seated upright position, threshold acuity was reduced, the resistive and reactive components of the acoustic impedance were greater, and the effects of stapedius and tensor tympani muscle contractions on the compliance at the tympanic membrane were reduced in the inverted (upside-down) position. The increase in acoustic impedance, which is probably due to an increase in the hydrostatic pressure of the labyrinthine fluids, accounted for only about half the decrease in threshold acuity.

Determination of the attenuation coefficients from the measured frequency characteristics of the windings of power transformers. Part 1. Theoretical consideration

2021 ◽  
Vol 1 (1) ◽  
pp. 13-22
Author(s):  
Vasily S. LARIN ◽  
◽  
Daniil A. MATVEEV ◽  
Keyword(s):  
Equivalent Circuit ◽  
High Frequency ◽  
Transfer Functions ◽  
Power Transformers ◽  
Reactive Component ◽  
Input Admittance ◽  
Vector Fitting ◽  
Transformer Winding ◽  
Resistive Component ◽  
High Frequency Resonance

To model high-frequency processes and determine the stresses on the internal insulation of transformer windings, reliable high-frequency models of power transformers are required. The accuracy of modeling high-frequency resonance processes in the windings depends on how correctly the model reproduces the natural frequencies and damping of free oscillations in the windings. To construct and verify high-frequency models of power transformers, it is necessary to have experimentally obtained data on the values of damping factors. There is a known method for determining the winding damping factors based on measurements of the voltage transfer functions at the internal points of the windings and their subsequent processing using the vector fitting technique, but its application is not always possible in practice. The article presents the results of theoretical studies performed for a simplified transformer winding equivalent circuit. It is shown that the damping factors can be estimated from the width of the resonance peaks of the frequency responses of the voltage modulus and reactive component at the midpoint of the equivalent circuit, and from the input admittance resistive component and current in the neutral of the considered resonance circuit.

scholarly journals Selective oxidation of 5-hydroxymethylfurfural into 2,5-diformylfuran over VPO catalysts under atmospheric pressure

RSC Advances ◽  
2019 ◽  
Vol 9 (25) ◽  
pp. 14242-14246 ◽  
Author(s):  
Jinhua Lai ◽  
Kai Liu ◽  
Shuolin Zhou ◽  
Du Zhang ◽  
Xianxiang Liu ◽  
...  
Keyword(s):  
Selective Oxidation ◽  
Atmospheric Pressure ◽  
Heterogeneous Catalysts ◽  
Air Pressure ◽  
Vanadium Phosphate ◽  
Atmospheric Air ◽  
Molar Ratios ◽  
Vpo Catalysts

Vanadium phosphate oxide (VPO) heterogeneous catalysts with different V/P molar ratios were prepared. VPO exhibited highly selective oxidation of HMF. The highest DFF yield of 83.6% was obtained under atmospheric air pressure.

Normative Sweep Frequency Impedance Measures in Healthy Neonates

2014 ◽  
Vol 25 (04) ◽  
pp. 343-354 ◽  
Author(s):  
Venkatesh Aithal ◽  
Joseph Kei ◽  
Carlie Driscoll ◽  
Andrew Swanston ◽  
Katrina Roberts ◽  
...  
Keyword(s):  
Middle Ear ◽  
Otoacoustic Emissions ◽  
Static Pressure ◽  
Auditory Brainstem ◽  
Ear Canal ◽  
Sweep Frequency ◽  
Tone Frequency ◽  
Automated Auditory Brainstem Response ◽  
Brainstem Response ◽  
Stapedial Reflex

Background: Diagnosing middle ear disorders in neonates is a challenging task for both audiologists and otolaryngologists. Although high-frequency (1000 Hz) tympanometry and acoustic stapedial reflex tests are useful in diagnosing middle ear problems in this age group, they do not provide information about the dynamics of the middle ear in terms of its resonance frequency (RF) and mobility. The sweep frequency impedance (SFI) test can provide this information, which may assist in the diagnosis of middle ear dysfunction in neonates. Purpose: This study aimed to investigate the feasibility of testing neonates using the SFI technique, establish normative SFI data for RF and mobility of the middle ear in terms of changes in sound pressure level (ΔSPL in dB), and describe the dynamics of the middle ear in healthy Australian neonates. Study Sample: A prospective sample of 100 neonates (58 males, 42 females) with a mean gestational age of 39.3 wk (SD = 1.3 wk; range = 38–42 wk), who passed all three tests, namely, automated auditory brainstem response, transient evoked otoacoustic emissions, and 1000 Hz tympanometry, were included in this study. Data Collection and Analysis: A SFI research prototype was used to collect the data. First, the SPL in the ear canal was measured as a probe-tone frequency was swept from 100–2000 Hz with the ear canal static pressure held constant at 200 daPa. Then, this measurement was repeated with the static pressure reduced in 50 daPa steps to –200 daPa. Additional measurement was also performed at the static pressure, where the peak of the 1000 Hz tympanogram occurred. A graph showing the variation of SPL against frequency at all static pressures was plotted. From this graph, the RF and ΔSPL at tympanometric peak pressure (TPP) were determined. Descriptive statistics and an analysis of variance (ANOVA) were applied to the RF and ΔSPL data with gender and ear as independent variables. Results: The results showed two resonance regions of the outer/middle ear with the high RF (mean = 1236 Hz; 90% range: 830–1518 Hz) being approximately equal to four times that of the low RF (mean = 287 Hz; 90% range = 209–420 Hz). The low RF was more easily identifiable than the high RF. The ΔSPL at the low RF (mean = 8.2 dB; 90% range = 3.4–13 dB) was greater than that at the high RF (mean = 5.0 dB; 90% range = 1.5–8.1 dB). There were no significant differences or interactions between genders and ears. Conclusion: The study showed that the SFI is a feasible test of middle ear function in neonates. The SFI results revealed two regions of resonance with the lower resonance (287 Hz) possibly related to the movements of the outer ear canal wall and higher resonance (1236 Hz) related to the resonance of the middle ear. The normative data developed in this study will be useful in evaluating outer and middle ear function in neonates.

STRUCTURAL CHARACTERISTICS OF La2O3 THIN FILM GROWN ON LaB6

2012 ◽  
Vol 15 ◽  
pp. 61-66 ◽  
Author(s):  
Y. A. KAFADARYAN ◽  
S. I. PETROSYAN ◽  
G. R. BADALYAN ◽  
V. G. LAZARYAN ◽  
G. H. SHIRINYAN ◽  
...  
Keyword(s):  
Atmospheric Pressure ◽  
Lanthanum Oxide ◽  
Annealing Temperature ◽  
Structural Characteristics ◽  
Hexagonal Phase ◽  
Lanthanum Hexaboride ◽  
Air Pressure ◽  
X Ray ◽  
Different Temperatures ◽  
Structure Versus

Within the framework of hexagonal lanthanum oxide ( h - La 2 O 3) formation, lanthanum hexaboride film on sapphire substrate ( LaB 6/ Al 2 O 3) was oxidized at different temperatures (700-1000 °C) under reduced atmospheric pressure (1·10-2,1.5·10-1Torr) during 30 min. The composition evolution of La 2 O 3/ LaB 6 structure versus annealing temperature has been studied using XRD, FIR reflectivity spectroscopy, SEM and electron probe X-ray microanalysis (EDS). The annealing of the LaB 6 film at T =700 °C under air pressure of 1·10-2 Torr generates thin La 2 O 3 layer which exhibits as inferred from XRD the hexagonal phase. The hydratation of La 2 O 3/ LaB 6/ Al 2 O 3 in distilled water for 30 min and postannealing at 900 °C under air pressure of 1.5·10-1 Torr transform h - La 2 O 3 into hexagonal La ( OH )3 phase accompanied monoclinic LaO ( OH ) and lanthanum oxide carbonate hydrate species.

scholarly journals On the explosion at Okhta

1919 ◽  
Vol 95 (673) ◽  
pp. 508-515
Keyword(s):  
Atmospheric Pressure ◽  
Pressure Wave ◽  
Air Pressure ◽  
Loss Of Life ◽  
Considerable Loss ◽  
Rapid Passage

On April 29, 1915, at about 8.15 P. M., a violent explosion occurred at the Okhta explosives factory, destroying several buildings and causing a considerable loss of life. A great number of the inhabitants of the capital heard the explosion, others could see the flames and columns of smoke: many, however, did not notice anything. The atmospheric pressure-wave caused by the explosion forced open the windows in many buildings of the capital; and even in places as distant as Pulkovo, Tsarkoe Selo, and Pavlovsk, its effects were very marked. The barographs installed in the observatories of Petrograd and Pavlovsk, and in the seismological station at Pulkovo, indicated at the time of the explosion the passage of a well-marked condensation wave in the atmosphere, but the corresponding change of atmospheric pressure was very small, not exceeding 0·3 mm. at Petrograd, 0·15 mm. at Pulkovo, and 0·1 mm. at Pavlovsk. If the barographs had been installed in the open air, and not sheltered from the action of external atmospheric influences, they would undoubtedly have shown greater changes in the atmospheric pressure (∆ p ). Although, under ordinary conditions, the air-pressure inside and outside a building is always the same, yet in the rapid passage of an intense wave of explosion there would not be time enough for these two pressures to become equal, and it is easy to see, therefore, that the condensation of the air must have been in reality much greater than as shown by the barographs. In the building of the Principal Physical Observatory the effect of the explosion was very slight, for I was there at the time, and did not notice anything.

Eustachian Tube Function and Middle Ear Barotrauma Associated with Extremes in Atmospheric Pressure

1996 ◽  
Vol 105 (11) ◽  
pp. 887-892 ◽  
Author(s):  
Takashi Miyazawa ◽  
Hiromi Ueda ◽  
Noriyuki Yanagita
Keyword(s):  
Hyperbaric Oxygen ◽  
Eustachian Tube ◽  
Middle Ear ◽  
Atmospheric Pressure ◽  
Eustachian Tube Function ◽  
Tube Function ◽  
Hyperbaric Exposure ◽  
Normal Adults ◽  
Hyperbaric Conditions

Eustachian tube (ET) function was studied by means of sonotubometry and tubotympano-aerodynamography (TTAG) prior to and following exposure to hypobaric or hyperbaric conditions. Forty normal adults were subjected to hypobaric pressure. Fifty adults who underwent hyperbaric oxygen (HBO) therapy also were studied. Following hypobaric exposure, 14 of 80 ears (17.5%) exhibited middle ear barotrauma. Following hyperbaric exposure, 34 of 100 ears (34%) exhibited middle ear barotrauma. Dysfunction of the ET, characterized by altered active and passive opening capacity, was more prevalent following exposure to extremes in atmospheric pressure compared to baseline. The ET function, which was impaired after the first HBO treatment, improved gradually over the next 2 hours. Overall, however, ET function was worse after the seventh treatment The patients who developed barotrauma exhibited worse ET function prior to hypobaric or hyperbaric exposure. Thus, abnormal ET function can be used to predict middle ear barotrauma prior to exposure to hypobaric or hyperbaric atmospheric pressure.

Eustachian Tube Function and Retraction of the Tympanic Membrane

1980 ◽  
Vol 89 (3_suppl) ◽  
pp. 65-66 ◽  
Author(s):  
Jörgen Holmquist ◽  
Ulf Renvall ◽  
Pål Svendsen
Keyword(s):  
Tympanic Membrane ◽  
Eustachian Tube ◽  
Middle Ear ◽  
Air Pressure ◽  
Eustachian Tube Function ◽  
Present Material ◽  
Pressure Equalization ◽  
Air Volume ◽  
Middle Ear Cholesteatoma ◽  
Tube Function

The medial displacement of the tympanic membrane or the retracted tympanic membrane is a common clinical finding. Also, retractions are looked upon as the precursor of middle ear cholesteatoma. In current otologic literature there seems to be some dispute whether the retractions of the tympanic membrane are caused by negative intratympanic air pressure or by shrinkage of middle ear adhesions pulling the tympanic membrane or part of it medially. In this study only ears with posterior/superior retractions of the tympanic membrane were investigated. Tympanometry revealed that only 33% of the ears did have middle ear pressure within ± 100 mm H2O. After insertion of a polyethylene tube through the tympanic membrane, the eustachian tube function was tested using the air pressure equalization technique. None of the ears could change the negative air pressure upon swallowing. Planometric measurements on the x-ray of the mastoid air cell system of the present material deviate from those of a normal material, indicating a significantly smaller air volume in the present material. It may be concluded that dysfunction of the eustachian tube and a small air volume of the mastoid are characteristic features of an ear with posterior/superior retraction of the tympanic membrane.

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