Recent advances in the field of audiology have indicated that there has been a growing concern regarding the potential damage to the hearing mechanism induced by recreational noise exposure from personal music devices (PMD). Regular PMD use may have a long-term damaging effect on the outer- and inner hair cells of the cochlea which may result in a progressive hearing loss. As PMDs have advanced to a stage where the memory of the devices are able to contain hours of listening content, the environments where these devices are being used are rapidly expanding. Many young adults tend to use their PMDs whilst exercising. Exercise in itself induces physiological and metabolic changes such as increased blood flow and oxygen levels within the structures of the cochlea. The purpose of this study was to determine the differential impact and short-term effects of simultaneous cardiovascular workout and personal music device (PMD) use on the otoacoustic emissions of young adults. Seven female and five male subjects completed three testing conditions: (i) one hour exposure to PMD use in isolation, (ii) one hour exposure to cardiovascular workout in isolation, and (iii) one hour simultaneous exposure to PMD use and cardiovascular workout. Distortion product otoacoustic emissions (DPOAEs) were conducted prior to, as well as directly following each testing condition, as primary indicator of cochlear responses emitted through a preset stimulus frequency sequence measuring the 2f₁ - f₂ (75 – 70 dB SPL) and constructing a plot of DPOAE levels as a function of frequency. While each of the testing conditions on its own did not result in statistically significant changes of the DPOAE response, a highly significant different profile in the DPOAE response level increase/decrease for the higher frequencies (6-8 kHz) was obtained when comparing the different sessions to each other. Where exposure to cardiovascular workout showed a clear trend of an increased DPOAE response level between the pre-exposure and post-exposure testing from 2 kHz to 8 kHz with a maximum increase at 6 kHz, both the music only condition and the combined condition where the cardiovascular workout was combined with music resulted in a significant different profile. During combined exposure a clear trend of decreased DPOAE response amplitudes between the pre-exposure and post-exposure testing were seen for the higher frequencies. These findings may support the notion of a clear effect of cardiovascular workout on the otoacoustic emissions at higher test frequencies, measured by DPOAEs when performed with and without music exposure. / Dissertation (MLOG)--University of Pretoria, 2014. / tm2015 / Speech-Language Pathology and Audiology / MLOG / Unrestricted

Objective: This study aimed to systematically review and analyse the available peer-reviewed literature reporting on the results of distortion product otoacoustic emissions (DPOAEs), transient evoked otoacoustic emissions (TEOAEs) and click auditory brainstem responses (c-ABRs) in adults with type 1 and type 2 diabetes mellitus (T1DM and T2DM). Method: A comprehensive literature search was conducted across three electronic databases to identify English; peer-reviewed articles that included results of OAEs (DPOAEs and TEOAEs) and c-ABR tests in adult subjects with DM. Articles were selected according to predetermined selection criteria and critically reviewed independently by two researchers. Results: 15 studies met the inclusion criteria for the systematic review while nine articles qualified for inclusion in the meta-analysis. DPOAE studies reported significantly reduced amplitudes with only one study reporting larger amplitudes. Abnormal TEOAEs were reported in all TEOAE studies, although these abnormalities were not always significant. Significantly delayed c-ABRs were reported in all ABR studies. Analysis of c-ABR mean wave latencies identified longer latencies for DM subjects, particularly for wave III and V, as well as for IPL I-III and I-V. Conclusions: Subjects with T1DM and T2DM may present with clinical or subclinical impairment of the cochlear outer hair cells and both the peripheral and central auditory pathway. / Dissertation (MA)--University of Pretoria, 2016. / Speech-Language Pathology and Audiology / MA / 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

Background: Distortion product otoacoustic emissions (DPOAEs) are a promising screening technique for the early detection of subtle noise induced cochlear function changes. Objectives: To determine the applicability of DPOAEs as a health surveillance technique for the early detection of noise induced hearing loss (NIHL) in workers at a steel manufacturing industry. Methods: DPOAEs were recorded in 20 participants with no history of occupational noise exposure and 20 participants exposed to noise in the steel manufacturing industry. Participants were not exposed to noise for at least 48 hours prior to testing. All participants were male with normal audiometric thresholds of ?15 dB HL. The DPOAE presence and response amplitude levels for different frequencies were compared between the two groups. The study further evaluated the short-term test-retest repeatability of DPOAE measurements, and also compared the total test duration of performing DPOAEs to the duration of screening audiometry. Results: The noise exposed group had statistically significantly lower DPOAE response amplitudes than the control group for all the tested frequencies; (p&#0600.001) at 2002 to 4004 Hz, and (p=0.01, p=0.001) at 6348 and 7996 Hz respectively, suggesting more cochlear damage in the noise exposed group due to early outer hair cell damage. DPOAEs showed very good reproducibility, and the average duration of performing a set of DPOAEs was significantly shorter (461 ± 68.2 seconds) than the duration of performing audiometry (591 ± 76.9 seconds), p&#0600.001. Conclusion: DPOAEs appeared to be a sensitive technique in detecting noise induced subtle cochlear function changes. DPOAEs could be used as a health surveillance technique for the early detection of NIHL in the steel manufacturing industry. / Dissertation (M Communication Pathology)--University of Pretoria, 2016. / Speech-Language Pathology and Audiology / M Communication Pathology / Unrestricted

The purpose of this study was to investigate further the characteristics of hearing loss in ventriculoperitoneal (VP) shunted hydrocephalus. Twelve (VP) shunt treated hydrocephalus children participated in this study. The etiology of the hydrocephalus was either intraventricular hemorrhage or spina bifida. A recent neurological examination reported the shunt to be patent in each child. Audiometric examination included pure tone air conduction thresholds, tympanometry, contralateral and ipsilateral acoustic reflex thresholds and distortion product otoacoustic emissions (DPOAEʹs). A unilateral, high frequency, sensorineural hearing loss was found in the ear ipsilateral to shunt placement in 10 (83%) of the 12 shunt treated hydrocephalic children. No hearing loss was observed the ear contralateral to shunt placement. Based on the pure tone findings coupled with the decrease in DPOAE amplitude in the shunt ear, the hearing loss appears to be cochlear in nature. It is hypothesized that the cochlear hydrodynamics are disrupted as the result of fluid pressure reduction within the perilymph being transmitted via a patent cochlear aqueduct as a reaction to the reduction of CSF via a patent shunt. In addition, a concomitant brainstem involvement is evidenced in the ART pattern possibly produced by the paten shunt draining CSF from the subdural space resulting in cranial base hypoplasia.

No description available.

This paper provides an overview of developmental timetables relevant to hearing and of current pediatric audiological techniques and practices. The first sections summarize structural and functional development of the auditory pathway and the development of primary auditory processing. These developmental sequences appear to follow similar paths in humans and animals. Speech and music perception involve more complex processing and are strongly influenced by experience. Hearing disorders affect the perception of complex sounds in a variety of ways, depending on the site(s) of lesions. Early onset hearing impairment, including conductive loss from chronic otitis media, can seriously impede language development. Language cannot develop normally without adequate speech stimulation. Sensitive and inexpensive techniques are available for performing neonatal hearing screening, and early intervention has a positive effect on development of language skills in hearing-impaired children. Thus, the National Institute of Health has recommended nationwide universal newborns hearing screening. The rationale and methodology of universal screening programs is summarized in the chapter. Advances in the field of the genetics of hearing impairment are also reviewed Recent advances in the field of auditory physiology - coupled with longstanding concerns about delayed identification of hearing impairment - have precipitated public health initiatives (National Institute of Health, 1993) and legislation for neonatal hearing screening programs (Blake & Hall, 1990). Pediatric audiology, once more “art” than science, is now largely based on physiologic methods rather than observed behavior. With current techniques, it is not only possible to detect hearing impairment at birth but also to determine the site of the lesion and to obtain close estimates of hearing threshold at specific frequencies (Werner, Folsom, & Mancl, 1993). Habilitative measures, including amplification, can begin within weeks of birth. Protocols for the management of hearing impairment are guided not only by the site of the lesion but by the developmental sequences and interactions among all of the child’s sensory modalities. This chapter provides an overview of developmental timetables relevant to hearing and of current pediatric audiological techniques and practices.

Previous studies show that pure tone thresholds are strongly correlated with distortion product otoacoustic emission amplitudes when evaluating the frequency range from 1 to 8 kHz (Avan & Bonfils, 1993). Little is known about correlations between these two measures at higher frequencies from 9-16 kHz. This study compared pure tone thresholds and distortion product otoacoustic emissions (DPOAEs) in this high frequency range for 29 normal hearing subjects ages 18-30. Pure tone thresholds were obtained at 250-16 kHz and distortion product otoacoustic emissions (DPOAE) 2,211-17,675 were measured in the same ears. DPOAE amplitudes were measured using a constant F1/F2 ratio of 1.2, with F2 values ranging from 2,211-17,675 Hz. Data obtained from 50 ears showed a decline in DPOAE amplitude with increasing frequency of the F1 and F2 primary stimulus tones. Behavioral thresholds demonstrated an increase with increasing frequency of the pure tone stimulus. Pearson r-correlation analysis demonstrated a weak relationship between measures. Further investigation revealed that equipment variables prevented accurate readings.

No description available.

Die Modulation von Distorsionsprodukt-Otoemissionen (DPOAE) durch Töne tiefer Frequenz ist ein Methode, mit der die Auswirkung von Verlagerungen der kochleären Trennwand auf die Funktion des kochleären Verstärkers untersucht werden kann. Damit bietet sie einen neuen objektiven Ansatz zur Diagnostik unterschiedlicher kochleärer Hörstörungen sowie zur Untersuchung physiologischer Mechanismen der Kochlea. Durch einen tieffrequenten Ton (f = 32,8 Hz) werden die DPOAE in Abhängigkeit von dessen Phase periodisch verändert. Die Ausprägung der Modulation hängt von den Parametern des Tieftons und der Primärtöne (mit den Frequenzen f1 und f2) ab. Bei zwölf normalhörenden Probanden wird der Einfluß des Tieftonpegels, der Primärtonpegel und der Primärtonfrequenzen auf die Modulation der DPOAE mit der Frequenz 2f1-f2 untersucht. Die Ergebnisse dieser Methode werden mit denen der subjektiven Phasenaudiometrie bei diesen Probanden verglichen. Mit den Primärtonfrequenzen f1 = 2,5 und f2 = 3 kHz steigt die mittlere Modulationstiefe der DPOAE mit zunehmendem Tieftonpegel sowie mit abnehmenden Primärtonpegeln nichtlinear. Mit hohem Tieftonpegel (L = 115 dB SPL) und geringen Primärtonpegeln (bis zu L1 = 50 und L2 = 30 dB HL) sind DPOAE-Pegelverläufe mit zwei Minima und zwei Maxima pro Tieftonperiode zu beobachten. Die Pegelminima liegen kurz nach der maximalen Druck- bzw. Sogphase des Tieftons vor dem Trommelfell, entsprechend der maximalen Auslenkung der kochleären Trennwand in Richtung Scala vestibuli bzw. Scala tympani. Sie zeigen eine mittlere Latenz von 4 ms gegenüber den Verdeckungsmaxima der subjektiven Mithörschwelle im Phasenaudiogramm, die wahrscheinlich durch die Summe der Antwortzeit der aktiven kochleären Prozesse und der Laufzeit der DPOAE-Signale retrograd aus der Kochlea zur Meßsonde im äußeren Gehörgang zustande kommt. Mit geringeren Tieftonpegeln (L = 110 dB SPL) bzw. höheren Primärtonpegeln (ab L1 = 55 und L2 = 40 dB HL) sowie höheren Primärtonfrequenzen (f1 = 4, f2 = 4,8 kHz) sind nur noch jeweils ein DPOAE-Pegelminimum und -maximum pro Tieftonperiode zu beobachten. Mit den Primärtonfrequenzen f1 = 5 und f2 = 6 kHz zeigt sich keine Modulation der DPOAE mehr. Die Ergebnisse werden unter Verwendung einer Boltzmannfunktion zweiter Ordnung als Annäherung an die mechano-elektrische Transferfunktion äußerer Haarzellen simuliert. Bei einigen Probanden werden außerdem die Modulation der DPOAE mit der Frequenz 3f1-2f2 durch den tieffrequenten Ton sowie der Einfluß spontaner otoakustischer Emissionen (SOAE) auf die Messung tieftonmodulierter DPOAE untersucht. / Low-frequency modulation of distortion product otoacoustic emissions (DPOAE) is a method which allows to investigate the effect of the displacement of the cochlear partition on the function of the active cochlear process. It offers a new objective approach to diagnose different sensory hearing disorders as well as to investigate physiological cochlear mechanisms. The DPOAE are modulated by a low-frequency tone (with the frequency f = 32,8 Hz), depending on its phase. The extent of this modulation depends on the acoustic parameters of the suppressing low-frequency tone and the stimulating primary tones (f1 and f2). In twelve normal hearing subjects the influence of the low-frequency tone level, the levels and the frequencies of the primary tones on the modulation of the DPOAE with the frequency 2f1-f2 are investigated. In these subjects, the phase-dependent masked subjective threshold is also registered. The results of both methods are compared. With the primary tone frequencies f1 = 2,5 and f2 = 3 kHz the mean value of the DPOAE modulation depth presents a nonlinear growth with increasing low-frequency tone level and decreasing primary tone levels, respectively. With high low-frequency tone level (L = 115 dB SPL) and low primary tone levels (up to L1 = 55 and L2 = 40 dB HL), the time course of the DPOAE level shows two minima and two maxima within one period of the low-frequency tone. The minimal DPOAE levels are registered shortly after the phases of maximal condensation and rarefaction of the low-frequency tone in front of the eardrum, respectively, corresponding to the largest displacement of the cochlear partition towards the scala tympani and the scala vestibuli. The time course of the DPOAE level shows a mean latency of 4 ms with regard to the masking patterns of the phase-dependent masked threshold, due to the response time of the active cochlear process and the retrograde travelling time of the DPOAE. With lower low-frequency tone levels (L1 = 110 dB SPL), higher primary tone levels (from L1 = 55, L2 = 40 dB HL), and higher primary tone frequencies (f1 = 4, f2 = 4,8 kHz), respectively, the DPOAE level presents only one maximum and one minimum per period of the low-frequency tone. With the primary frequencies f1 = 5 and f2 = 6 kHz no modulation of the DPOAE is registered. The results are simulated using a second-order Boltzmann function as an approximation of the mechano-electric transfer function of the outer hair cells. Additionally, in some subjects the low-frequency modulation of the DPOAE with the frequency 3f1-2f2 and the influence of spontaneous otoacoustic emissions (SOAE) on the registration of low-frequency modulated DPOAE are investigated.