Background: Multidrug-resistant tuberculosis (MDR-TB) patients receive aminoglycosides as part of their treatment. These drugs are ototoxic, and can cause permanent damage to the cochlea, resulting in a debilitating hearing loss, which has a negative impact on an individual's quality of life. Early detection and management of an ototoxic hearing loss can minimise the impact of the hearing loss on the person's social, emotional, and vocational wellbeing. While patients with MDR-TB are often very ill, it might be ideal to use an objective test that does not require active participation from the patient. In this way, the reliability and validity of the test will not be affected by the patient's state. Distortion product otoacoustic emissions (DPOAEs) at 2f1-f2 are a viable option, as it evaluates cochlear function, specifically the outer hair cells, which are affected first by ototoxic medication. Method: This thesis used a sequential study design aimed to determine the DPOAE stimulus parameters that yield (a) the highest level and the most reliable, sensitive and specific DPOAEs reported in the literature, (b) the highest level and the most reliable DPOAEs in healthy, normally hearing adults, and (c) the most sensitive and specific DPOAEs in participants with MDR-TB patients receiving ototoxic medication. High frequency pure tone audiometry (defined in this thesis as frequencies > 8 kHz) was used as the gold standard. Descriptive statistics, the intraclass correlation coefficient, Pearson's correlation coefficient and mixed model analyses were used to analyse the data. Results: Systematic review: The results of the systematic review indicated an L1/L2 setting of 75/75 dB SPL and f2/f1 value from 1.20 to 1.22 yielded the highest level DPOAEs. The systematic review results for stimulus parameters that yielded the highest test-retest reliability, sensitivity and specificity were inconclusive. Preliminary study with healthy normal hearing participants: The results of the preliminary study in healthy, normal-hearing participants indicated that the highest levels of DPOAEs were elicited with L1/L2 intensity levels of 65/65 and 65/55 dB SPL, and f2/f1 ratios of 1.18, 1.20 and 1.22, as determined by mixed model analyses (p < 0.05). These same stimulus parameters yielded the most reliable DPOAEs in both ears, as determined by intraclass correlation coefficient analysis. Main study with healthy, normal-hearing participants: Descriptive statistics and mixed model analysis showed stimulus intensity levels L1/L2 of 65/55 dB SPL, and f2/f1 ratios of 1.18 and 1.20, elicited the largest DPOAEs. The ratio of 1.20 yielded the largest DPOAEs < 5000 Hz and f2/f1 ratio of 1.18 the largest DPOAEs ≥ 5000 Hz. The second highest DPOAE levels were elicit by L1/L2 = 65/65 dB SPL and f2/f1 = 1.18. The test-retest reliability in this sample was not influenced by changing the stimulus parameters, and DPOAEs were only unreliable at an f2 frequency of 8 000 Hz. Study in participants with MDR-TB: Results in participants with MDR-TB receiving ototoxic medication indicated that the highest levels of DPOAEs were elicited with L1/L2 = 65/55 and an f2/f1 ratio of 1.18 at f2 ≥ 5000 Hz, followed by 65/65 and 1.18. For f2 < 5000 Hz, stimulus intensities of L1/L2 = 65/55 and an f2/f1 ratio of 1.20 yielded the largest DPOAE levels. Relating to sensitivity and specificity, the stimulus parameter combination of 65/55 dB and 1.18 detected the highest number of ears with outer hair cell damage in participants with MDR-TB receiving ototoxic medication. Conclusion: It should be considered to use an f2/f1 ratio of 1.18 for f2 ≥ 5000 Hz and 1.20 for f2 < 5000 Hz when monitoring for ototoxicity, to assist with early identification of outer hair cell damage, in conjunction with high frequency pure tone audiometry. This finding needs to be confirmed in a larger sample of participants with MDR-TB receiving ototoxic medication.

The primary aim of the research was to describe hearing function in a group of children with chronic renal dysfunction receiving treatment in an academic hospital in Johannesburg, South Africa. Specific objectives in the study were to determine the prevalence of hearing loss in paediatric patients with chronic renal dysfunction; to describe the type, degree and configuration of the hearing loss; and to establish if there was a relationship between the presenting hearing loss and the severity of renal dysfunction, the different treatment regimens, duration of renal dysfunction, and the duration of treatment. One hundred children between the ages five -18 years participated in the study and comprised 65 males and 35 females. The mean age of the participants was 11.68 years. A cross-sectional, descriptive, quantitative research design was employed. All participants underwent a case history interview and a full audiological examination which included an otoscopic examination, immittance testing (tympanometry and ipsilateral acoustic reflex testing), pure tone audiometry including extended high frequency testing up to 16 kilohertz as well as diagnostic distortion product otoacoustic emission testing. A record review was also done. Both descriptive and inferential statistics were used to analyse the collected data. Inferential statistics included parametric measures using multiple regression measures as well as non parametric measures using the Kruskal-Wallis statistical analysis. Results revealed that there was a high prevalence of hearing loss in children with chronic renal dysfunction. Results from the extended high frequency pure tone testing as well as the diagnostic distortion product testing revealed that the most common hearing loss was a low and high to ultrahigh frequency mild sensorineural hearing loss. The study showed that there was no relationship between the severity of hearing loss and the severity of renal dysfunction, or the duration of renal dysfunction and the duration of treatment. However, the study showed that there was a relationship between the severity of hearing loss and certain treatments, that is, v haemodialysis and the use of ototoxic medication such as loop diuretics, tuberculosis medication, and antimalarial medication. As the potential to miss hearing loss in this population is high, the research highlighted the importance of extended high frequency audiometry as well as diagnostic distortion product otoacoustic emission testing for the use of ototoxic monitoring in patients with chronic renal dysfunction. The research also highlighted the need for further research in this area as well as the need for educating medical personnel and caregivers working with children with chronic renal disease.

No description available.

It has been suggested that the presence of a limited area of damaged outer hair cells (OHCs) with intact inner hair cells, which may not be detected on the conventional audiogram, results in unbalanced neural activity between Type I and Type II fibers leading to tinnitus. In normal-hearing tinnitus patients, DPOAEs provided ambiguous data of OHC function when compared to non-tinnitus controls. Hearing loss in the extended high-frequency (EHF) region may decrease DPOAEs evoked at lower frequencies. Results of EHF audiometry in tinnitus patients are limited. The aim of the study was to evaluate DPOAEs and EHF thresholds in normal-hearing patients reporting unilateral tinnitus in left ear. Thus, each subject acted as their own control. Data were obtained for 26 subjects with bilateral hearing thresholds10, 12.5, 14, and 16 kHz. The DP-grams were measured in the 0.5-8 kHz range using 65/55-dB SPL primaries and f2/f1=1.2. The data analyses included DPOAEs with S/N>3 dB. Median audiometric data showed that thresholds in the left ears were significantly higher than those in the right ears at all four EHFs. Mean DPOAE levels of the left ears were lower than those of the right ears in the frequency range above 1 kHz. Additionally, a paired-comparison test of DPOAE levels of each patient’s right and left ear revealed significant differences at 6 and 8 kHz. The results indicate that: 1. OHC impairment in the most basal region reduces contribution to more apically generated DPOAEs; 2. OHC impairment in a limited area, which may be revealed by DPOAEs but not by conventional audiometry, can contribute to tinnitus generation; and 3. patients with unilateral tinnitus and normal hearing on the conventional audiogram are likely to demonstrate hearing loss in the EHF region.

No description available.

No description available.

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

The clinical value of oto-acoustic emissions (OAEs) for the identification of the integrity of outer hair cell function has been proven numerous times in research studies, and OAEs are commonly included in the audiological test battery used by audiologists. The technological advances in this field, however, require continuous research to determine the value of new equipment. The main objective of this study was to determine the test-retest reliability of distortion product oto-acoustic emissions (DPOAEs) and transient evoked oto-acoustic emissions (TEOAEs). The subjects were female adults between 18 and 25 years of age, and 30 ears were used for this study. All participants had normal middle-ear function, normal hearing sensitivity (pure tone thresholds) and present OAEs. DPOAEs and TEOAEs were performed at specific time intervals to determine the test-retest reliability, and an OAE-gram was generated by combining DPOAE and TEOAE test results. These measures were performed as an initial measure (M1), after five minutes (M2), after an hour (M3), after a week (M4) and after a month (M5). The test-retest reliability was calculated by analysing the statistics quantitatively. Results were analysed to determine the variance between each participant individually at different time intervals, and also to determine the variance of the group as a whole at different time intervals. Through this analysis high test-retest reliability between the different tests was proven. Inferential statistical Analysis of Variance (ANOVA) and Intraclass Correlation Coefficient (ICC) proved that the test-retest reliability of DPOAEs, TEOAEs and the OAE-gram (generated through a combination of the DPOAE and TEOAE results) was consistent throughout all periods of testing. The highest correlation existed between immediate re-measurements, while the largest difference was observed between M1 and M3. High test-retest reliability for all tests conducted at different time intervals from original measures were confirmed. Recommendations that arose from this study are further research in the normal hearing population for better generalization, research into specific variables between subjects, research with longer time between different tests, as well as the test-retest reliability in pathologic populations. / Dissertation (MCommunication Pathology)--University of Pretoria, 2017. / Speech-Language Pathology and Audiology / MCommunication 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

No description available.