The biological process known as activated sludge (AS) in conjunction with membrane separation technology for the treatment of wastewater has been employed for over four decades. While, membrane biological reactors (MBR) are now widely employed, the phenomenon of membrane fouling is still the most significant factor leading to performance decline of MBRs. Although much research has been done on the subject of MBR fouling over the past two decades, many questions remain unanswered, and consensus within the scientific community is rare. However, research has led to one system parameter generally being regarded as a contributor to membrane fouling, extracellular polymeric compounds (EPS). EPS, and more specifically, the soluble fraction of EPS known as soluble microbial products (SMP), must be further investigated in order to better understand membrane fouling. The biological activity and performance of the MBR is affected by myriad operational parameters, which in turn affects the SMP generated. A commonly varied operational parameter is, depending on the specific treatment needs of a MBR, the sludge retention time (SRT). This study aims to characterize the SMP in three bench-scale MBRs as the SRT is gradually lowered. By studying how the SMP change as the operation of the system is altered, greater understanding of how SMP are related to fouling can be achieved. At the onset of the study, a steady state was established in the system with a SRT of 20 days. Upon stabilization of a 20 day SRT, the system was gradually transitioned to a five and a half day SRT, in stepwise adjustments. Initially, both the trans-membrane pressure (TMP) and the SMP concentrations were at relatively low values, indicating the presence of minimal amounts of biofilm on the membrane surfaces. As the system was altered and more activated sludge was wasted from the reactors, the SRT inherently decreased. As the lower SRT was transitioned and established, the data from TMP measurements, as well as the results from SMP determination, confirmed the development of increased amounts of biofilm formed. An apparent relationship was observed between the operational condition of a lower SRT and the SMP found in the system.

Speech audiometry is an important aspect of audiological testing. One aspect of speech audiometry is the measurement of an individual's speech reception threshold (SRT). Materials needed to measure the SRT are available in many languages; however, recorded materials for the Mongolian Language are not widely available. The purpose of this study was to develop a list of psychometrically equivalent words for evaluating the hearing abilities of native Mongolian speaking individuals. A set of 90 commonly used bisyllabic Mongolian words were digitally recorded by a male and female talker of Mongolian and then evaluated by 20 native Mongolian listeners. A final list of 28 words with relatively steep psychometric function slopes were selected and digitally adjusted to reduce intensity threshold variability among words. Digital recordings of the 28 psychometrically equivalent bisyllabic words are available on compact disc to facilitate SRT testing of native Mongolian speakers.

The purpose of this study was to develop, digitally record, evaluate, and equate Spanish trisyllabic words which could then be used in the measurement of the speech reception threshold. A selection of 90 frequently utilized trisyllabic words were selected and then digitally recorded by male and female talkers of Spanish and presented to 20 subjects with normal hearing beginning at 6 dB below their pure-tone average (PTA) and ascending in 2 dB increments until one of the following criteria had been met: (a) the participant responded correctly to 100% of the test items, or (b) the presentation level reached 16 dB HL. Using logistic regression, psychometric functions were calculated for each word. Twenty-eight trisyllabic words with the steepest psychometric function slopes were selected. To decrease the variability among the words the intensities were digitally adjusted to match the mean subject PTA (5.83 dB HL). The resulting lists included mean slopes at 50% threshold which ranged from 7.3 %/dB to 12.7 %/dB (M = 10.1) for the male talker recording and from 7.1 %/dB to 12.8 %/dB (M = 8.7) for the female talker. Digital recordings of the 28 final psychometrically equivalent trisyllabic words are available on compact disc.

Technologies for pretreatment of waste activated sludges (WAS) prior to digestion are of increasing interest to wastewater treatment utilities because of their promise for improving sludge digestibility and reducing the mass of biosolids remaining after digestion. While there has been considerable study of pretreatment processes, a common approach to describing the impact of pretreatments on sludge biodegradability has not been developed. The overall objective of this study was to develop protocols that can be employed to characterize the impact of pretreatment processes on WAS digestion. Sonication and ozonation were employed as models of physical and chemical pretreatment technologies respectively. A range of physical, chemical and biological responses were evaluated to assess the impact of pretreatment on WAS properties as well as digestibility. WAS samples that were generated over a range of solids residence times (SRTs) under controlled operating conditions were employed to facilitate an assessment of the interaction between pretreatment and WAS properties on digestibility. The VS, COD and soluble TKN responses indicated that a significant fraction of the WAS solids were solublized by sonication and ozonation, however, it appeared that the types of materials which were solublized was affected by the SRT at which the WAS was generated and the level of pretreatment. The results indicated that the impact of pretreatment on biodegradability of WAS was not described by solublization values exclusively without considering the SRT of the sludge and the level and type of pretreatment. A higher level of proteinaceous materials was preferentially solublized as the result of pretreatment. Respirometry revealed that both sonication and ozonation substantially reduced the viable heterotrophs in the sludge and modestly increased the readily biodegradable fraction of COD. The ultimate yields of CH4 and NH4 in BMP tests and VFAs in BAP tests revealed that pretreatment marginally increased the ultimate digestibility of the sludges. Only a high dose of ozonation substantially increased the digestibility of the 15 day SRT sludge. However, both sonication and ozonation substantially increased the rate of hydrolysis which is typically the rate limiting process in WAS digestion. The BMP test was not a useful test to evaluate the rate of methane generation due to inhibition of methanogens in the early days of BMP test for pretreated sludges. The comparison between VFA and ammonia responses in day 10 of BAP test and ultimate values of these responses after 60 days in BMP test revealed linear relationships between these responses. According to these relationships, a set of models were introduced in this study. The models can be employed to predict the ultimate methane and ammonia generation using soluble COD, VFA or ammonia responses in day 10 of BAP tests. The BAP test was determined to be a shorter test (10 days) than the BMP (55 to 60 days) test and could provide information on the rates of hydrolysis and acidification/ammonification processes. Characterization of biodegradable and non-biodegradable material in WAS samples was conducted using a simplified ADM1 model. The characterization also revealed that proteins are a substantial fraction of biodegradable materials. The estimated ammonia, VFA and methane values from the stoichiometric model were similar to the corresponding values from the experiments. This supported the validity of the simplified model for all sludges employed in this study.

Technologies for pretreatment of waste activated sludges (WAS) prior to digestion are of increasing interest to wastewater treatment utilities because of their promise for improving sludge digestibility and reducing the mass of biosolids remaining after digestion. While there has been considerable study of pretreatment processes, a common approach to describing the impact of pretreatments on sludge biodegradability has not been developed. The overall objective of this study was to develop protocols that can be employed to characterize the impact of pretreatment processes on WAS digestion. Sonication and ozonation were employed as models of physical and chemical pretreatment technologies respectively. A range of physical, chemical and biological responses were evaluated to assess the impact of pretreatment on WAS properties as well as digestibility. WAS samples that were generated over a range of solids residence times (SRTs) under controlled operating conditions were employed to facilitate an assessment of the interaction between pretreatment and WAS properties on digestibility. The VS, COD and soluble TKN responses indicated that a significant fraction of the WAS solids were solublized by sonication and ozonation, however, it appeared that the types of materials which were solublized was affected by the SRT at which the WAS was generated and the level of pretreatment. The results indicated that the impact of pretreatment on biodegradability of WAS was not described by solublization values exclusively without considering the SRT of the sludge and the level and type of pretreatment. A higher level of proteinaceous materials was preferentially solublized as the result of pretreatment. Respirometry revealed that both sonication and ozonation substantially reduced the viable heterotrophs in the sludge and modestly increased the readily biodegradable fraction of COD. The ultimate yields of CH4 and NH4 in BMP tests and VFAs in BAP tests revealed that pretreatment marginally increased the ultimate digestibility of the sludges. Only a high dose of ozonation substantially increased the digestibility of the 15 day SRT sludge. However, both sonication and ozonation substantially increased the rate of hydrolysis which is typically the rate limiting process in WAS digestion. The BMP test was not a useful test to evaluate the rate of methane generation due to inhibition of methanogens in the early days of BMP test for pretreated sludges. The comparison between VFA and ammonia responses in day 10 of BAP test and ultimate values of these responses after 60 days in BMP test revealed linear relationships between these responses. According to these relationships, a set of models were introduced in this study. The models can be employed to predict the ultimate methane and ammonia generation using soluble COD, VFA or ammonia responses in day 10 of BAP tests. The BAP test was determined to be a shorter test (10 days) than the BMP (55 to 60 days) test and could provide information on the rates of hydrolysis and acidification/ammonification processes. Characterization of biodegradable and non-biodegradable material in WAS samples was conducted using a simplified ADM1 model. The characterization also revealed that proteins are a substantial fraction of biodegradable materials. The estimated ammonia, VFA and methane values from the stoichiometric model were similar to the corresponding values from the experiments. This supported the validity of the simplified model for all sludges employed in this study.

Land application of anaerobically stabilized biosolids is a beneficial method of handling the solid residuals from a wastewater treatment plant. One of the main issues that restrict land application of biosolids is nuisance odors associated with biosolids. Despite its importance, few studies have been done to enhance our knowledge of odor causing processes. This study was conducted to evaluate the effects of some factors that have been thought to be linked to odor generation from biosolids. The first part of this study has looked at the role of metals, iron and aluminum in particular, in determining the odor causing processes. The results showed that iron correlated well with headspace organic sulfur odor. In general, as the iron content of sludge increased greater amounts of odorous sulfur gases were produced from dewatered biosolids cakes. Aluminum did not show any relationship with organic sulfur odors. Parameters commonly used for assessing the performance of anaerobic digesters (volatile solids reduction (VSR), residual biological activity (RBA) and effluent volatile fatty acid (VFA) content) also showed no correlation with odors. The second part of the study focused on determining the impact of anaerobic digester solids retention time (SRT) on the odor generation from dewatered biosolids cakes and also on elucidating the nature and impact of the various Extracellular Polymeric Substances (EPS) fractions on odors. The results showed that odors decreased with an increase in the anaerobic digester SRT. VSR and RBA correlated with odors; however, as only one type of sludge was assessed, the conclusions about any relationship may not be universal. The results also showed that sulfur gas generation was a function of EPS material bound to iron, again showing that iron plays an important role in odor generation from dewatered sludge cakes. The third part of the study looked at the effects of advanced digestion processes on odor generation. Digested sludge from acid/gas and temperature phased anaerobic digestion systems were analyzed in the lab. The results show that both acid/gas system and temperature phased digestion had a positive impact on odor generation from dewatered biosolids cake. Comparison of sludge from pancake shaped and egg shaped digesters showed that egg shaped digester was more efficient with regard to odor reduction. / Master of Science

Les conditions de culture de microalgues autotrophes en système ouvert associant microalgues / bactéries ont été étudiées au cours de ce travail de thèse. L'objectif était de développer un procédé de valorisation des nutriments (N, P) contenus dans la phase liquide des digestats issus de méthanisation agricole. Dans un premier temps, une synthèse sur les filières de méthanisation suivi d'un état de l'art sur les microalgues et leurs conditions de culture ont permis de mettre en évidence les principaux paramètres d'influence spécifiques à l'influent étudié, tels que la coloration, et les interactions avec les processus de nitrification/dénitrification. Ainsi, dans le but de mieux comprendre les mécanismes et d'évaluer les impacts des paramètres principaux, un pilote de laboratoire composé de 6 réacteurs de 2,5 litres a été conçu et des analyses spécifiques ont été développées au laboratoire. A partir de ces outils, l'effet de la couleur et de la lumière sur la pénétration de la lumière et sur la croissance algale a été quantifié. Ensuite, l'influence du ratio N/P du milieu a été testée, ce qui a permis de mettre en exergue le stockage du phosphore par les microalgues, leur permettant de continuer leur croissance lorsque le phosphore du milieu est épuisé. Par la suite, le transfert du dioxyde de carbone et son impact sur la croissance des microalgues ont été étudiés. La productivité algale est fonction de la quantité de CO2 fournie à la culture et chute à 0 sans injection. Enfin, l'étude du temps de séjour des solides et de leur fréquence d'extraction a révélé que la nitrification-dénitrification est un mécanisme important d'élimination de l'azote dans une culture algale en continu et en système ouvert. Il peut même s'avérer prédominant par rapport à l'assimilation de l'azote par les microalgues dans certaines conditions. La proportion de chacun de ces processus peut néanmoins être contrôlée par ces paramètres. Ces expérimentations ont par ailleurs permis de mieux comprendre les interactions entre microalgues et bactéries nitrifiantes ainsi que la prédominance des genres d'algues en fonction des conditions de culture. Les microalgues sont de meilleures compétitrices sur le phosphore que les bactéries nitrifiantes. De plus, lorsque le phosphore n'est pas limitant, la nitrification est réduite en proportion de la productivité algale. En cas de limitation en phosphore et avec une faible lumière disponible, les genres d'algues qui se sont montrés dominants sont Scenedesmus sp. et Chlorella sp. Respectivement. Les essais expérimentaux ont été complétés par le développement ou l'adaptation de modèles biocinétiques capables de représenter la croissance algale et l'épuration assez fidèlement. A partir de cette modélisation, différentes configurations ont été simulées pour dimensionner un lagunage algal à haut rendement et ainsi mieux comprendre et apprécier la faisabilité d'une culture algale pour extraire les nutriments des digestats. / The culture conditions of autotrophic microalgae in open system associating microalgae/bacteria were studied in this thesis. The objective was to develop a process to valorize nutrients (N, P) contained in the liquid phase of digestate coming from agricultural methanization. First, a synthesis of anaerobic digestion process followed by a state of art on microalgae and their culture conditions allowed to highlight the main parameters specific to the studied influent, such as coloration, and the interactions with nitrification-denitrification processes. To better understand the mechanisms and study the impact of the main parameters, a laboratory-scale pilot composed of six 2.5L-reactors was designed and specific analyses were developed at the laboratory. With the help of those tools, effects of color and light on light penetration and on microalgae growth were quantified. Then, the study of the N:P ratio of the medium allowed to highlight the phosphorus storage by microalgae, allowing them to continue their growth while the phosphorus of the medium was depleted. Thereafter, the carbon dioxide transfer and its impact on microalgae growth were studied. The algal productivity is a function of the quantity of provided CO2 into the culture and fall to zero without injection. Finally, the study of solid retention time and extraction rate revealed that nitrification-denitrification is an important mechanism for nitrogen removal in a continuous algae culture in open system. This mechanism may even be predominant compared to nitrogen assimilation by microalgae under certain conditions. The proportion of each of these processes may still be controlled by these parameters. These experiments have also provided insight into the interactions between microalgae and nitrifying bacteria and the predominance of algae genera depending on culture conditions. Microalgae are better competitors on phosphorus than nitrifying bacteria. Furthermore, in non-limiting phosphorus conditions, nitrification is reduced in proportion to algal productivity. Scenedesmus and Chlorella proved to be dominant respectively when phosphorus and light are limiting. The experimental trials were completed by the development or the adaptation of biokinetic models able to represent quite accurately microalgae growth and nitrogen removal. From this model, different configurations were simulated to design high rate algal pond and assess the feasibility of the algal culture to extract nutrients from digestate.

The measurement of cardiorespiratory fitness has been extensively researched among adult populations, but very few researchers have focused their attention on the cardiorespiratory fitness of children and adolescents. Due to various constraints of direct 2max VO testing, various indirect testing methods have been developed of which the 20-m Shuttle Run Test is the most widely used testing method. The influence of various anthropometric, physical and motor performance components as well as certain demographic factors such as gender, race, living area, and sport participation as well as physical activity level on the 2max VO value of participants seems to suggest that 2max VO can be predicted by including these components in prediction models. It is against this background that the objectives of this study are provided. The following four objectives of the study were achieved through a literature review: Firstly, to name and describe the various direct and indirect methods for determining 2max VO ; secondly, to provide a review on the findings with regard to the aerobic performances or 2max VO values of children and adolescents; thirdly, to discuss the possible influence of various anthropometric, physical and motor-performance components on the aerobic performances or 2max VO values of the last-mentioned groups of subjects. As part of this objective, other literature-identified factors such as certain demographic factors (living area, race and gender), sport and physical activity participation level which may also influence the aerobic performances or 2max VO values of the participants, were also discussed; fourthly, all literature identified models for the prediction of aerobic performances or 2max VO values in children, and in adolescents were mentioned and discussed. The next few objectives were achieved through a selected group, cross-sectional experimental research design; fifthly, to develop a valid 2max VO prediction function from several anthropometric measurements and demographic factors such as gender, race and living area as well as sport participation level of a cohort of adolescents living in the Tlokwe Local Municipality (Potchefstroom area) of North West Province, South Africa; sixthly, to develop a 2max VO prediction function from the physical and motor-performance components as well as demographic variables such as gender, race and living area as well as sport participation level of a cohort of adolescents living in the Tlokwe Local Municipality (Potchefstroom area) of North West Province, South Africa; and finally, to determine the validity of the 20-m SRT to estimate the 2 VO and 2max VO of a cohort of adolescent boys in the Tlokwe Local Municipality (Potchefstroom area) of North West Province, South Africa. In order to fulfil the fifth and sixth objectives of the study, a total of 214 grade 8 adolescents (boys: 88 and girls: 126) (age: 15.82 ± 0.68 years) of high schools in the Tlokwe Local Municipality (Potchefstroom area) of the Dr Kenneth Kaunda District of the North West Province, South Africa were purposefully selected from pre-acquired class lists, from six secondary schools. Data was collected by means of various questionnaires, anthropometric measurements and physical and motor-performance tests, which also included the 20-metre SRT. For the fulfilment of the final objective of the study, 52 boys were purposefully selected from the above-mentioned group that completed various questionnaires as well as the 20-m SRT while they were fitted with a portable gas analyser apparatus. With regard to the anthropometric and demographic variable prediction model, the forward stepwise regression analysis results showed that muscle mass percentage, sport participation level, stature, hip circumference and ectomorphy act as significant predictors (p ≤ 0.05) of the indirect, 20-m SRT 2max VO values of a cohort of adolescents. Muscle mass percentage emerged as the strongest predictor (59%) of adolescents’ 2max VO values, followed by sport participation level (6%), ectomorphy (2%), stature (1%) and hip circumference (1%). The physical, motor-performance and demographic prediction model revealed that 10-metre speed, sit-up repetitions, sport participation level, handgrip strength, Vertical Jump Test (VJT) Tendo peak power, maximal heart rate (HRmax), living area, right shoulder external rotation flexibility (RPSERT), horizontal jump test distance (HJT) and right Modified Thomas iliopsoas flexibility (RMTIT) served as significant predictors (p ≤ 0.05) of the indirect, 20m-SRT-derived 2max VO values of a cohort of adolescents. However, only 10-metre speed served as a major contributor (53.5%) to the indirect 2max VO values of the adolescents. The rest of the variables contributed 17.4% to the overall variance in 2maxVO values. Overall, the last-mentioned anthropometric, physical, motor performance and demographic variables were responsible for 70.5% of the variance in the 2max VO values of the adolescents. Cross-validations also revealed that both models are valid for predicting the 20-m SRT-derived indirect 2max VO values of this cohort of adolescents. The 20-m SRT validity study showed that a significant difference (p ≤ 0.05) existed between the predicted indirect 2max VO results (42.06 ± 4.53 ml/kg/min) as obtained from the 20-m SRT booklet and the direct 2max VO results (50.62 ± 7.11 ml/kg/min) as obtained from the gas analysis. Furthermore, significant differences (p ≤ 0.05) were observed between the direct and indirectly predicted 2 VO values at levels 1-9 of the 20-m SRT compared to no significant differences at levels 10 and 11 of the 20-m SRT. In conclusion, to the researchers’ knowledge, this is the first study to develop valid 2max VO prediction functions from the use of several anthropometric measurements, physical and motorperformance test results and demographic information for a group of South African adolescents. Furthermore, this is also the first study to reveal that the 20-m SRT is not a valid test for the accurate prediction of 2 VO and 2max VO of a cohort of adolescent South African boys. The results of this study may possibly allow practitioners in the field of Human Movement Science to more accurately screen the indirect 2max VO values of adolescents by making use of easily obtainable measures and information, instead of the predicted 2max VO values of the 20-m SRT / PhD (Human Movement Science), North-West University, Potchefstroom Campus, 2014

The measurement of cardiorespiratory fitness has been extensively researched among adult populations, but very few researchers have focused their attention on the cardiorespiratory fitness of children and adolescents. Due to various constraints of direct 2max VO testing, various indirect testing methods have been developed of which the 20-m Shuttle Run Test is the most widely used testing method. The influence of various anthropometric, physical and motor performance components as well as certain demographic factors such as gender, race, living area, and sport participation as well as physical activity level on the 2max VO value of participants seems to suggest that 2max VO can be predicted by including these components in prediction models. It is against this background that the objectives of this study are provided. The following four objectives of the study were achieved through a literature review: Firstly, to name and describe the various direct and indirect methods for determining 2max VO ; secondly, to provide a review on the findings with regard to the aerobic performances or 2max VO values of children and adolescents; thirdly, to discuss the possible influence of various anthropometric, physical and motor-performance components on the aerobic performances or 2max VO values of the last-mentioned groups of subjects. As part of this objective, other literature-identified factors such as certain demographic factors (living area, race and gender), sport and physical activity participation level which may also influence the aerobic performances or 2max VO values of the participants, were also discussed; fourthly, all literature identified models for the prediction of aerobic performances or 2max VO values in children, and in adolescents were mentioned and discussed. The next few objectives were achieved through a selected group, cross-sectional experimental research design; fifthly, to develop a valid 2max VO prediction function from several anthropometric measurements and demographic factors such as gender, race and living area as well as sport participation level of a cohort of adolescents living in the Tlokwe Local Municipality (Potchefstroom area) of North West Province, South Africa; sixthly, to develop a 2max VO prediction function from the physical and motor-performance components as well as demographic variables such as gender, race and living area as well as sport participation level of a cohort of adolescents living in the Tlokwe Local Municipality (Potchefstroom area) of North West Province, South Africa; and finally, to determine the validity of the 20-m SRT to estimate the 2 VO and 2max VO of a cohort of adolescent boys in the Tlokwe Local Municipality (Potchefstroom area) of North West Province, South Africa. In order to fulfil the fifth and sixth objectives of the study, a total of 214 grade 8 adolescents (boys: 88 and girls: 126) (age: 15.82 ± 0.68 years) of high schools in the Tlokwe Local Municipality (Potchefstroom area) of the Dr Kenneth Kaunda District of the North West Province, South Africa were purposefully selected from pre-acquired class lists, from six secondary schools. Data was collected by means of various questionnaires, anthropometric measurements and physical and motor-performance tests, which also included the 20-metre SRT. For the fulfilment of the final objective of the study, 52 boys were purposefully selected from the above-mentioned group that completed various questionnaires as well as the 20-m SRT while they were fitted with a portable gas analyser apparatus. With regard to the anthropometric and demographic variable prediction model, the forward stepwise regression analysis results showed that muscle mass percentage, sport participation level, stature, hip circumference and ectomorphy act as significant predictors (p ≤ 0.05) of the indirect, 20-m SRT 2max VO values of a cohort of adolescents. Muscle mass percentage emerged as the strongest predictor (59%) of adolescents’ 2max VO values, followed by sport participation level (6%), ectomorphy (2%), stature (1%) and hip circumference (1%). The physical, motor-performance and demographic prediction model revealed that 10-metre speed, sit-up repetitions, sport participation level, handgrip strength, Vertical Jump Test (VJT) Tendo peak power, maximal heart rate (HRmax), living area, right shoulder external rotation flexibility (RPSERT), horizontal jump test distance (HJT) and right Modified Thomas iliopsoas flexibility (RMTIT) served as significant predictors (p ≤ 0.05) of the indirect, 20m-SRT-derived 2max VO values of a cohort of adolescents. However, only 10-metre speed served as a major contributor (53.5%) to the indirect 2max VO values of the adolescents. The rest of the variables contributed 17.4% to the overall variance in 2maxVO values. Overall, the last-mentioned anthropometric, physical, motor performance and demographic variables were responsible for 70.5% of the variance in the 2max VO values of the adolescents. Cross-validations also revealed that both models are valid for predicting the 20-m SRT-derived indirect 2max VO values of this cohort of adolescents. The 20-m SRT validity study showed that a significant difference (p ≤ 0.05) existed between the predicted indirect 2max VO results (42.06 ± 4.53 ml/kg/min) as obtained from the 20-m SRT booklet and the direct 2max VO results (50.62 ± 7.11 ml/kg/min) as obtained from the gas analysis. Furthermore, significant differences (p ≤ 0.05) were observed between the direct and indirectly predicted 2 VO values at levels 1-9 of the 20-m SRT compared to no significant differences at levels 10 and 11 of the 20-m SRT. In conclusion, to the researchers’ knowledge, this is the first study to develop valid 2max VO prediction functions from the use of several anthropometric measurements, physical and motorperformance test results and demographic information for a group of South African adolescents. Furthermore, this is also the first study to reveal that the 20-m SRT is not a valid test for the accurate prediction of 2 VO and 2max VO of a cohort of adolescent South African boys. The results of this study may possibly allow practitioners in the field of Human Movement Science to more accurately screen the indirect 2max VO values of adolescents by making use of easily obtainable measures and information, instead of the predicted 2max VO values of the 20-m SRT / PhD (Human Movement Science), North-West University, Potchefstroom Campus, 2014

While there is a clear and immediate need for reliable speech audiometry materials to evaluate the speech recognition threshold (SRT), these recorded materials are not available in Cebuano, a language of the Philippines with 15.8 million speakers. The purpose of this study was to develop, digitally record, evaluate, and psychometrically equate a set of Cebuano trisyllabic words for use in measuring the SRT. To create the SRT materials, common Cebuano trisyllabic words were digitally recorded by a male talker of Cebuano and presented for evaluation to 20 native speakers of Cebuano with normal hearing. Based on psychometric performance, a set of 21 trisyllabic words with a psychometric function slope >7%/dB that allowed threshold adjustments to the pure tone average were selected and digitally adjusted. The resulting mean psychometric function slopes at 50% for the 21 SRT trisyllabic materials was 10.2%/dB. The results of the current study are comparable to those found in other languages. Digital recordings of the trisyllabic words are available on compact disc.