Search results for "Acoustic Emission"
showing 10 items of 56 documents
Serial measurements of transient evoked otoacoustic emissions (TEOAEs) in healthy newborns and in newborns with perinatal infection.
1993
Detection of hearing impairment in early childhood is difficult. We serially recorded transient evoked otoacoustic emissions (TEOAEs) to search for signs of ototoxicity in term, healthy newborns and compared the results to a second group of term babies treated for perinatally acquired bacterial infection with ampicillin plus either cefotaxime or plus aminoglycoside. At initial evaluation, in the group of 45 healthy children born at term, well reproducible emissions were observed in all but two children. In each of these two, initially well reproducible TEOAEs were detected in one ear only. At the time of the second recording (mean at day 8.5) excellent emissions were seen in all ears of all…
On the threshold of effective well infant nursery hearing screening in Western Sicily.
2012
Abstract Objective To determine the feasibility and effectiveness of well-infant nursery hearing screening programme for the early identification of hearing impairment, based on transient evoked otoacoustic emission (TEOAE) with a high “screen sensitivity” reducing the number of more expensive secondary level exams. Methods The newborns were screened by non-specialist health workers in well babies nursery at the twentieth day of life for 6 years consecutive. Based on PASS/FAIL criteria and presence/absence of audiological risk factors the newborns were divided into four groups each one with its personal step programme: G1 – PASS without risk factor, free to go home; G2 – PASS with risk fact…
Auditory Neuropathy in Children
2001
Auditory neuropathy is a sensorineural disorder characterized by absent or abnormal auditory brainstem evoked potentials and normal cochlear outer hair cell function. A variety of processes is thought to be involved in its pathophysiology and their influence on hearing may be different. We present here the diagnostic sequence and management of two new cases of auditory neuropathy in breastfeeding children.
An experimental comparative study of dexamethasone, melatonin and tacrolimus in noise-induced hearing loss.
2008
The calcineurin inhibitor tacrolimus (TCR) and the pineal gland hormone and antioxidant melatonin (MLT) have been shown to possess otoprotective properties against noise-induced hearing loss (NIHL). In contrast, dexamethasone (DXM) was not effective as an otoprotective agent against NIHL. Further studies are needed to understand the exact molecular mechanisms involved.Exposure to noise pollution and use of audio devices for long periods of time at high volume is known to cause hearing loss or NIHL. Our goal was to evaluate the effectiveness of various known compounds such as the anti-inflammatory DXM, the antioxidant MLT and the immunosuppressant TCR against NIHL.Thirty-two Wistar rats were…
E-ABR in Patients with Cochlear Implant: A Comparison between Patients with Malformed Cochlea and Normal Cochlea
2019
Objectives This study aims to compare the electrical auditory brainstem response (EABR) following cochlear implant (CI) surgery in pediatric subjects with cochlear malformation and a normal cochlea, in order to assess the sensitivity of EABR and to evaluate the surgery outcome. Materials and methods A total of 26 pediatric subjects who were deaf and scheduled for CI surgery were enrolled into this case control study. Group A (n=20) included subjects with a normo-conformed cochlea. Group B (n=6) included subjects with cochlear malformation. Subjects were evaluated with EABR immediately (T0) and 6 months (T1) post-CI surgery. The EABR Waves III and V average amplitude and latency were compare…
The influence of the temperature of insulation oil on the results of measurements of the acoustic emission signals generated by partial discharges
2005
The subject matter of this paper refers to the improvement of the acoustic emission method (AE) used for evaluation of partial discharges (PDs) generated in paper-oil insulation systems of power appliances. The paper presents the measurement and analysis results of the AE signals generated by partial discharges of the surface type (SPDs). The AE signals were measured on the surface of a transformer tub using a broad-band contact transducer, and then they were subject to a time-frequency analysis. The measurements were taken while heating transformer oil in the range from 30 to 85°C with gradation of every 5°C. For time runs, amplitude and energy density spectra the descriptor values that ch…
Acoustic Emission-Based Condition Monitoring and Remaining Useful Life Prediction of Hydraulic Cylinder Rod Seals
2021
The foremost reason for unscheduled maintenance of hydraulic cylinders in industry is caused by wear of the hydraulic seals. Therefore, condition monitoring and subsequent estimation of remaining useful life (RUL) methods are highly sought after by the maintenance professionals. This study aimed at investigating the use of acoustic emission (AE) sensors to identify the early stages of external leakage initiation in hydraulic cylinders through run to failure studies (RTF) in a test rig. In this study, the impact of sensor location and rod speeds on the AE signal were investigated using both time- and frequency-based features. Furthermore, a frequency domain analysis was conducted to investig…
Elastoplastic Damaging Model for Adhesive Anchor Systems. I: Theoretical Formulation and Numerical Implementation
2011
In this and in the companion paper, the mechanical response of adhesive anchor systems is theoretically and numerically predicted and experimentally observed. The theoretical prediction is on the basis of an elastoplastic damaging model formulated to predict the structural response associated with the development of a fracture in adhesive anchor systems. This part describes the analytical model developed in the framework of a thermodynamically consistent theory, which assumes adhesion where the structure is sound, and friction in correspondence with the fracture. Isotropic damage is considered. The model can predict the structural behavior at the interface between two surfaces of ductile, b…
White Etching Crack Root Cause Investigations
2014
White etching crack (WEC) failure is distinct to classical fatigue and driven by the composition of lubricants under special loading conditions; for example, slippage and electricity. The white etching area (WEA) within WEC contains carbon supersaturated ferrite (bcc-iron) and carbides, with a size of a few nanometers. This article presents investigations supporting the hypothesis that WEC processes start within a failure-free period by successive accumulation of a structural distortion. This can be measured by acoustic emission. Failure statistics show a steep ascent in the Weibull diagram (s values beyond 1) leading to the assumption that WEC processes start unsuspicious, as one would see…
Analysis of pectin biopolymer phase states using acoustic emissions.
2019
Acoustic emissions are stress or elastic waves produced by a material under external load. Since acoustic emissions are generated from within and transmitted through the substance, the acoustic signature provides insights into the physical and mechanical properties of the material. In this report, we used a constant velocity probe with force and acoustic emission monitoring to investigate the properties of glass phase and gel phase pectin films. In the gel phase films, a constant velocity uniaxial load produced periodic premonitory acoustic emissions with coincident force variations (saw-tooth pattern). SEM images of the gel phase microarchitecture indicated the presence of slip planes. In …