Scuba diving as a recreational activity has increased in popularity over the past few years. It is believed that repeated exposure to the hyperbaric environment may have a long term effect on the auditory system. The research literature has given a lot of attention to acute injury but is very limited relating to the long term implications of scuba diving. Previous research studies did not perform a full audiometric test battery. A comprehensive audiological assessment is critical to determine in which part of the ear a pathology may occur during recreational diving. This study endeavoured to assess and describe the hearing abilities and middle ear functioning of the recreational scuba diver and investigate the possibility that diving, on a recreational level, may have an influence on the auditory system. In order to achieve the aims of this study, a descriptive, correlation research design was selected. The results of the current study indicate that scuba diving on a recreational level does not have a significant effect on the hearing and middle ear functioning of the individual, with the exclusion of static compliance. It appears that the inevitable compression and decompression that the middle ears are exposed to during scuba diving might have a more permanent effect on the elasticity of the tympanic membrane. Finally this study aims to increase the awareness of possible risks concerning the auditory system relating to scuba diving and in so doing, attribute to the prevention, diagnosing and intervention of diving related ear injuries. / Dissertation (M (Communication Pathology))--University of Pretoria, 2007. / Speech-Language Pathology and Audiology / M (Communication Pathology) / unrestricted

Hearing loss in early childhood and infancy often goes undetected because it exhibits no obvious indication and symptoms. The primary aim of newborn hearing screening is to detect permanent hearing loss. Since otoacoustic emissions (OAE) and automated auditory brainstem response (AABR) are sensitive to hearing loss, they are often used as screening tools. On the other hand, these screening tests can be affected by transient outer ear and middle ear conditions that are often present at birth. This is an especially characteristic state of affairs for NICU neonates. These false positive results may render screening programmes inefficient and can lead to increased parental anxiety. Wideband acoustic immittance (WAI) has shown potential for accurate assessment of middle ear function in neonates, and is therefore recommended as an adjunct tool for newborn hearing screening programmes. The main aim of the study was to determine the feasibility of using WAI in NICU neonates in terms of tone and click stimuli. Testing was conducted in the NICU units of three private hospitals in Pretoria. As part of the selection criteria all the neonates had to pass both DPOAE and AABR screenings before they were included in the study. In total, 56 NICU infants (106 ears) with a gestation age of between 32 and 37 weeks and a mean gestational age of 35.6 weeks who passed both DPOAE and AABR hearing screens in one or both ears were selected. For WAI measurements there were two measurements, one for each channel in the probe (chirp and tone stimuli). Normative regions were defined across the wideband reflective spectrum for both tone and chirp stimuli and for integrated frequency ranges. The chirps and tone stimuli compared relatively well with each other at the 90th percentile with the same amount of reflectance across all frequencies. The median reflectance reached a minimum of 0.67 at 1-2 kHz but increased to 0.7 below 1 kHz and 0.72 above 2 kHz for the tone stimuli. For chirp stimuli the median reflectance reached a minimum of 0.51 at 1-2 kHz but increased to 0.68 below 1 kHz and decreased to 0.5 above 2 kHz. Results of this study identified WAI patterns that had not previously been reported in the literature. High reflective values were obtained across all frequency ranges, especially in the frequency ranges below 3 kHz and above 4 kHz. The age of the neonates when tested (mean gestational age 35.6 weeks, with a standard deviation of 1.6) might have influenced the results. The neonates in this study were of a very young age compared to the ages of the infants in previous studies on WAI. Environmental noise in NICU might have influenced the results. Additional research is required to investigate WAI testing in ears with and without dysfunction. / Dissertation (M Communication Pathology)--University of Pretoria, 2016. / Speech-Language Pathology and Audiology / M Communication Pathology / Unrestricted

A student manual of audiological procedures with accompanying laboratory assignments does not presently exist at the University of South Florida (USF). In the first year of the four year Au.D. program at USF, students are enrolled in Audiology Laboratory Clinic I, II, and III, in consecutive semesters. Groups of four to six students meet weekly for a 3-1/2 hour clinical laboratory session to receive training in test instruction, test procedures, test application, and test interpretation. The purpose of the first year Audiology laboratory clinic sessions is to prepare the student for clinical experience in year two of the Au.D program at USF. In preparation for these laboratory sessions, it was discovered that materials related to test procedures are currently scattered throughout a variety of texts, journals, manuals, educational software, videos, and web sites. No one source contains all the needed information on any given test procedure. In addition, specific procedures outlined in documents [American Standards Institute (ANSI) and the American Speech-Language-Hearing Association (ASHA)] are not consistently used by the different sources. Thus, there is no standard procedural manual containing laboratory assignments that lead to the development of appropriate clinical testing skills by a first year Au.D student. A standard test procedural manual for pure tone audiometry, speech audiometry, and immittance testing, with assignments, was developed to assist in the cultivation of the students testing skills. The manual contains test history, purposes, procedures, scoring guidelines, interpretations, and limitations for each test. Laboratory assignments include practice exercises using a computer simulator, classmates, and volunteers. Each assignment is accompanied by discussion questions to enhance and augment student understanding. A reference list is available to obtain further information on each topic area. This manual will be made available to the first year Au.D student as well as to the advanced Au.D student who would benefit from an all-inclusive, updateable source providing the best possible clinical procedures. The final product will be available for a fee in a notebook type format to allow for the inclusion of additional topics and updates as the standards of practice in Audiology change.

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No description available.

Professional research project (Au.D.)--University of South Florida, 2001. / Title from PDF of title page. / Document formatted into pages; contains 146 pages. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: A student manual of audiological procedures with accompanying laboratory assignments does not presently exist at the University of South Florida (USF). In the first year of the four year Au.D. program at USF, students are enrolled in Audiology Laboratory Clinic I, II, and III, in consecutive semesters. Groups of four to six students meet weekly for a 3-1/2 hour clinical laboratory session to receive training in test instruction, test procedures, test application, and test interpretation. The purpose of the first year Audiology laboratory clinic sessions is to prepare the student for clinical experience in year two of the Au.D program at USF. In preparation for these laboratory sessions, it was discovered that materials related to test procedures are currently scattered throughout a variety of texts, journals, manuals, educational software, videos, and web sites. No one source contains all the needed information on any given test procedure. / ABSTRACT: In addition, specific procedures outlined in documents [American Standards Institute (ANSI) and the American Speech-Language-Hearing Association (ASHA)] are not consistently used by the different sources. Thus, there is no standard procedural manual containing laboratory assignments that lead to the development of appropriate clinical testing skills by a first year Au.D student. A standard test procedural manual for pure tone audiometry, speech audiometry, and immittance testing, with assignments, was developed to assist in the cultivation of the students testing skills. The manual contains test history, purposes, procedures, scoring guidelines, interpretations, and limitations for each test. Laboratory assignments include practice exercises using a computer simulator, classmates, and volunteers. Each assignment is accompanied by discussion questions to enhance and augment student understanding. / ABSTRACT: A reference list is available to obtain further information on each topic area. This manual will be made available to the first year Au.D student as well as to the advanced Au.D student who would benefit from an all-inclusive, updateable source providing the best possible clinical procedures. The final product will be available for a fee in a notebook type format to allow for the inclusion of additional topics and updates as the standards of practice in Audiology change. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

The field of early detection and intervention of hearing loss in neonates and infants has been marked by a growing international body of research investigating hearing screening programmes, protocols and outcomes of early detection for hearing loss. In South Africa, screening for neonates and infants in general and particularly for hearing loss is not common practice and is not meeting the needs of the South African population, with very few infants identified with hearing loss early in life. The Year 2002 Hearing Screening Position Statement recommends an intermediate step toward universal screening in the form of Targeted Newborn Hearing Screening (TNHS) as an option for developing countries with limited resources. The Neonatal Intensive Care Unit (NICU) provides a starting point for TNHS because it encompasses a number of risk factors for hearing loss. A combined descriptive and exploratory research methodology was followed to provide a comprehensive perspective on longitudinal hearing screening for NICU neonates and infants at a provincial hospital in South Africa. The quantitative methods included a structured interview to compile risk factor information. Immittance measurements used included acoustic reflex measurements, 226 Hz and 1000 Hz tympanometry. Automated Otoacoustic Emission (AOAE) as well as Automated Auditory Brainstem Response (AABR) screening was conducted. Routine follow-up visits at three month intervals were booked if a subject passed the screen and a follow-up screening for further testing was booked if a subject referred the screening. A total of 49 neonates and infants as well as mothers were enrolled in the first year and followed up for the second year of data collection period. The results indicated that the NICU had potential as platform for TNHS in South Africa. The high incidence of risk factors reported is more when compared with developed countries and highlights the importance of hearing screening in the at risk population for a developing country. The results confirmed reports that 226 Hz probe tone tympanometry produces erroneous responses in young infants. A high correspondence between high frequency tympanometry and AOAE results was found and underlines the need for differential diagnosis to accurately detect middle ear effusion and/or sensorineural hearing loss in neonates and infants. The unilateral AOAE refer rate (7%) was within range of the reported values for initial screening at discharge from the NICU. AABR results indicated a relatively high unilateral refer result (24%) and may be attributed to irritability and restlessness. The highest referral rates in the current study were recorded during the second and third visit and may be attributed to the presence of middle-ear pathology in older infants. The perceptions of mothers emphasized the lack of awareness regarding hearing and hearing loss in South Africa. Lack of knowledge may be a contributing actor to poor compliance with screening follow-up. Despite prevailing challenges, such as a low follow-up return rate, lack of awareness regarding the benefits of early detection of hearing loss, the effect of middle ear effusion on screening results, the cost of hearing screening and different priorities of the national healthcare system, such as Human Immunodeficiency Virus, demonstrated the NICU promise as platform for TNHS in South Africa. TNHS programmes may serve as starting point to direct universal neonatal hearing screening programmes in South Africa. / Dissertation (MCommunication Pathology)--University of Pretoria, 2008. / Speech-Language Pathology and Audiology / MComm Path / unrestricted

Rapid implementation of universal newborn hearing screening programs has exposed a need for a reliable test of middle ear function for timely identification of middle ear pathology and for differentiation between true sensorineural and conductive hearing losses. Use of higher probe tone frequencies for the assessment of immitance measures have proven to be more reliable and accurate in identifying MEE in infants. However a lack of classification-guidelines and age specific normative data exists. This study investigated the characteristics and normative values of high frequency tympanometric and acoustic reflex results for infants (n = 936 ears). Participants were 510 infants (262 male, 248 female) aged 0 – 12 months (mean age = 12.8 weeks) recruited from primary health care and immunization clinics in a South African community. A three-part procedure was performed on each test ear: 1) OAEs were recorded and pass results served as control variable for normal middle ear functioning; 2) 1000 Hz probe tone admittance, susceptance and conductance tympanograms were recorded and analysed in terms of shape, tympanometric peak pressure and maximum (peak) admittance; 3) 1000 Hz probe tone acoustic reflexes, measured with a 1000 Hz ipsilateral stimulus, were recorded and thresholds determined. Significant associations were observed between tympanogram shape, and OAE pass or fail results. 93% of ears with an OAE pass result displayed peaked tympanograms, while 79% of ears with absent OAE’s displayed flat tympanograms. Single peaked tympanograms were recorded in 782 ears (84%), double peaked tympanograms in 41 (4%) ears and flat sloping tympanograms in 112 (12%) ears. Admittance (Ya) tympanograms for the total sample displayed a mean admittance value of 2.9 mmho, with a standard deviation of 1.1 mmho. The 90th percent range was determined at 1.5 mmho (5th percentile) to 4.9 mmho (95th percentile). Mean tympanometric peak pressure in Ya tympanograms was 0.1 daPa, with a standard deviation of 61 daPa. The 90th percent range was -110 daPa to 90 daPa for the 5th and 95th percentiles respectively. Gender specific norms indicated a higher admittance for male ears. Age specific norms indicate a gradual increase in admittance indicating the need for age specific normative classification systems. Ipsilateral 1000 Hz stimuli acoustic reflex measurement proved successful with a 1000 Hz probe tone and present reflexes were recorded in 84% of ears tested. Significant association between acoustic reflex presence, OAE pass and peaked tympanogram results were observed. The normative tympanometric values derived from the cohort may serve as a guide for identification of middle ear effusion in neonates. High frequency tympanometry in combination with acoustic reflexes proves a useful measure for verifying middle ear functioning in young infants. / Dissertation (M (Communication Pathology))--University of Pretoria, 2006. / Speech-Language Pathology and Audiology / M (Communication Pathology) / unrestricted

This thesis deals with design and use synthetic circuit elements with higher-order immittance with controlled current sources to implement the frequency filters. Controlled current sources which are derived from the voltage variations are presented. They are current follower, current invertor and current operational amplifier. Low-pass and high-pass filter which are used synthetic elements are simulated on computer. The influence of real properities of active elements and passive elements tolerances on filter functionality is investigated. Selected circuit of frequency filter is realized and measured the frequency characteristic.

There is great interest in the development of new polar dielectric ceramics and multiferroic materials with new and improved properties. A family of tetragonal tungsten bronze (TTB) relaxors of composition Ba₆M³⁺Nb₉O₃₀ (M³⁺ = Ga³⁺, Sc³⁺ and In³⁺, and also their solid solutions) were studied in an attempt to understand their dielectric properties to enable design of novel polar TTB materials. A combination of electrical measurements (dielectric and impedance spectroscopy) and powder diffraction (X-ray and neutron) studies as a function of temperature was employed for characterising the dynamic dipole response in these materials. The effect of B-site doping on fundamental dipolar relaxation parameters were investigated by independently fitting the dielectric permittivity to the Vogel-Fulcher (VF) model, and the dielectric loss to Universal Dielectric Response (UDR) and Arrhenius models. These studies showed an increase in the characteristic dipole freezing temperature (T[subscript(f)]) with increase B-cation radius. Crystallographic data indicated a corresponding maximum in tetragonal strain at T[subscript(f)], consistent with the slowing and eventual freezing of dipoles. In addition, the B1 crystallographic site was shown to be most active in terms of the dipolar response. A more in-depth analysis of the relaxor behaviour of these materials revealed that, with the stepwise increase in the ionic radius of the M³⁺ cation on the B-site within the Sc-In solid solution series, the Vogel-Fulcher curves (lnf vs. T[subscript(m)]) are displaced to higher temperatures, while the degree of relaxor behaviour (frequency dependence) increases. Unfortunately, additional features appear in the dielectric spectroscopy data, dramatically affecting the Vogel-Fulcher fitting parameters. A parametric study of the reproducibility of acquisition and analysis of dielectric data was therefore carried out. The applicability of the Vogel-Fulcher expression to fit dielectric permittivity data was investigated, from the simple unrestricted (“free”) fit to a wider range of imposed values for the VF relaxation parameters that fit with high accuracy the experimental data. The reproducibility of the dielectric data and the relaxation parameters obtained by VF fitting were shown to be highly sensitive to the thermal history of samples and also the conditions during dielectric data acquisition (i.e., heating/cooling rate). In contrast, UDR analysis of the dielectric loss data provided far more reproducible results, and to an extent was able to partially deconvolute the additional relaxation processes present in these materials. The exact nature of these additional relaxations is not yet fully understood. It was concluded application of the Vogel-Fulcher model should be undertaken with great care. The UDR model may represent a feasible alternative to the evaluation of fundamental relaxation parameters, and a step forward towards the understanding of the dielectric processes in tetragonal tungsten bronzes.