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Audiology

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Browsing Audiology by Author "Govender, Cyril Devadas."

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    The development of a Zulu speech reception threshold test for Zulu first language speakers in KwaZulu-Natal (KZN).
    (2006) Panday, Seema.; Govender, Cyril Devadas.; Kathard, Harsha Mothilall.; Pillay, Mershen.
    The measurement of speech reception threshold (SRT) is best evaluated in an individual's first language. Currently there is a paucity of linguistically matched materials to measure the SRT of Zulu First Language Speakers (ZFLS) in Kwa Zulu-Natal (KZN). Therefore, the present study focused on developing and assessing a Zulu SRT word list for Zulu First language Speakers (ZFLS) in KZN, according to adapted criteria for SRT in Zulu. In addition, the application of the developed list was evaluated. The study therefore followed a two phase methodological framework. Phase one focused on the development and assessment of the word list. Phase two focused on the application of the word list in a normal hearing population from KZN. Phase one of the study was realized within a descriptive survey design and Phase two was realized using a within- participant quasi experimental design. Phase one included aims one and two of the study. Phase two included aim three of the study. However, each aim had several objectives which were realized consecutively. For aim one of the study, three objectives were achieved i.e. for objective one, 131 common bisyllabic words were identified by two Zulu speaking language interpreters and two tertiary educators. Eighty two percent of these words were described as bisyllabic verbs. The outcome of objective two concluded that 58 bisyllabic verbs were rated as being familiar, phonetically dissimilar and low tone verbs by five linguistic experts, using a three point Likert scale. The agreement among the raters was generally good for each criterion, according to the Kendall's co-efficient of concordance at 95% level of confidence. Two objectives were generated to realize aim two of the study. These included, the measurement of homogeneity of audibility of the 58 words selected in aim one and the acoustic analysis of the words. The findings for the homogeneity of audibility were based on a logistic regression analysis. Thirty normal hearing adult ZFLS (18-25 years) participated in this aim of the study. The mean slope of 50% for 28 words was 5.98%/dB. Therefore, 28 words were measured as being most homogenous. The 28 words were also assessed acoustically. The acoustic analysis indicated that the pitch contours confirm the prosodic pattern of the words selected in terms of Zulu linguistic structure, as the majority of the verbs (89%) indicated a difference in the pitch pattern between the two syllables. Furthermore, trends were noted with regard to the energy contours. The acoustical analysis supports the findings of objective one of aim two. For aim three of the study, twenty six normal hearing adult ZFLS, with functional proficiency in English were assessed. The SRT was measured using the developed Zulu SRT word list. In addition, the SRT was measured using the original CIDW2 list. The Pearson product moment correlation co-efficient was utilized for the measurement of the relationship between the SRT (Zulu) and the Pure Tone Average (PTA). Similarly, the Pearson product moment correlation between the SRT (English) and PTA was obtained. A good relationship between the SRT scores and PTA was reported when both lists were used. However, a stronger correlation between the Zulu SRT and PTA (r=.76) than with the English SRT and PTA (r=0.62) were noted. The results in aim one and aim two of the study highlighted the importance of adapting the criteria for SRT to suit the structure of the language. Aim three confirmed this premise as the implication of a stronger correlation may be related to the familiarity of the stimuli to the Zulu First Language Speaker. The study therefore contributed to both research and clinical implications. Some of the important research implications for the study include: the application of the Zulu SRT word list to a varied clinical population with a hearing disorder or loss, the standardization of the developed Zulu SRT word list on a larger sample, the development of SRT materials in other African languages in South Africa. Important clinical implications of the study include that the findings in the study support the need for speech material to be appropriate to the language of the client and the developed SRT word list in Zulu is applicable to adult ZFLS in KZN.
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    The feasibility of including Distortion Product Otoacoustic Emissions (DPOAEs) in the annual medical surveillance test battery for the identification of noise-induced hearing loss in a group of workers in a beverage manufacturing industry.
    (2013) Reddy, Tarryn Marisca.; Panday, Seema.; Govender, Cyril Devadas.
    The study investigated the feasibility of including DPOAEs in the annual medical surveillance test battery for the identification of NIHL in a group of employees in a manufacturing industry in KwaZulu-Natal. Feasibility was investigated by exploring the sensitivity, specificity and predictive efficiency of DPOAEs, the ability of DPOAEs to detect subtle noise-induced cochlea changes, the test-retest reliability of DPOAEs and lastly, the duration of time taken to conduct the DPOAE test bilaterally. A cross-sectional and repeated measures within-in participant design was utilized in the study. A purposive convenience sampling technique was used, as well as a stratified sampling approach in order to realize objective two of the study. The study consisted of 60 participants, which were further stratified into four test groups, i.e. Group A: 0-3 years, Group B: 3.1-6 years and Group C: 6.1-9 years and Group D: 9.1-13 years of working within the beverage manufacturing industry. A high sensitivity and negative predictive value was reported in the current study, suggesting that DPOAEs may be able to identify those who present with subtle cochlea changes as a result of exposure to occupational noise. The sensitivity of DPOAEs was 100% at 1, 2, 4, 6 and 8kHz in the right ear and at 4 and 6kHz in the left ear. The specificity of DPOAEs in the current study ranged between 55%-97% across the frequency range in the right ear and 49%-88% in the left ear. A negative predictive value of 100% was obtained bilaterally across the frequency range, except at 8kHz in the left ear. Visual inspection of the DPgram in the current study revealed a bilateral reduction in DPOAE amplitudes for all test groups in the high frequency region of the DP-Gram, namely, 5477Hz and 7303Hz, in the absence of a statistically significant difference (p>0.05). A greater frequency range appears to be affected in this group of workers, indicating that the type of noise, namely, impulse noise, may result in cochlea changes. Corresponding changes on the pure tone audiogram were not observed, however, noise notch configurations were observed for the groups with a longer history of noise exposure. This was not seen bilaterally as is typically expected with NIHL. Good test-retest reliability across the frequency range obtained in the current study further indicates the feasibility of including DPOAEs in the annual medical surveillance test battery. Additionally, the current study calculated an average of 86 seconds (1 minute 26 seconds) to conduct the DPOAE test bilaterally, confirming that DPOAEs are a quick test to administer. The findings of this study suggest that DPOAEs may be used to monitor early subtle noise-induced cochlea changes for workers exposed to noise in the beverage manufacturing industry as part of the annual medical surveillance test battery.
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    An investigation into the effects of sex difference and contralateral masking on the monaural brainstem auditory evoked response (Baer) obtained in a group of normal hearing Indian undergraduate university students.
    (1989) Govender, Cyril Devadas.; Fernandes, Carlos M. C.; Lazarus, Theophilus.
    The objectives of the investigation were to establish diagnostic reference data; and to examine and report on the effects of sex difference and contralateral masking on the normal BAER. BAERs were elicited from the target (R) ear using clicks presented at 70dBnHL both in the absence and presence of three (50, 6O and 70dBHL) levels of contralateral broadband masking noise. Relevant latency and amplitude data were obtained from 60 selected normal hearing Indian undergraduate female (N=30; X age = 20.33 years) and male (N=30; X age = 21.33 years) students aged between 18 and 25 years (X age = 20.73 years). Diagnostic reference data were established for the absolute latencies of peaks I to VI; relative latencies of peaks I-III; III-V and I-V; absolute amplitudes of peaks I and V and the relative amplitude ratio of peaks V:I. The application of the MANOVA revealed an overall significant (p < 0,05) sex difference effect while no significant differences were observed between the masked and non-masked normal BAER. Furthermore, there were no significant overall interactional effects of sex difference and masking on the BAER. These results are discussed in terms of the literature and implications for clinical application and further research.