A model that can accurately predict speech recognition for cochlear implant (CI) listeners is essential for the optimal fitting of cochlear implants. By implementing a CI acoustic model that mimics CI speech processing, the challenge of predicting speech perception in cochlear implants can be simplified. As a first step in predicting the recognition of speech processed through an acoustic model, vowel perception in severe speech-shaped noise was investigated in the current study. The aim was to determine the acoustic cues that listeners use to recognize vowels in severe noise and make suggestions regarding a vowel perception predictor. It is known that formants play an important role in quiet, while in severe noise the role of formants is still unknown. The relative importance of F1 and F2 is also of interest, since the masking of noise is not always evenly distributed over the vowel spectrum. The problem was addressed by synthesizing vowels consisting of either detailed spectral shape or formant information. F1 and F2 were also suppressed to examine the effect in severe noise. The synthetic stimuli were presented to listeners in quiet and signal-to-noise ratios of 0 dB, -5 dB and -10 dB. Results showed that in severe noise, vowels synthesized according to the whole-spectrum were recognized significantly better than vowels containing only formants. Multidimensional scaling and FITA analysis indicated that formants were still perceived and extracted by the human auditory system in severe noise, especially when the vowel spectrum consisted of the whole spectral shape. Although F1 and F2 vary in importance in listening conditions of quiet and less noisy conditions, the role of the two cues appears to be similar in severe noise. It was suggested that not only the availability formants, but also details of the vowel spectral shape can help to predict vowel recognition in severe noise to a certain degree. / Dissertation (MEng)--University of Pretoria, 2010. / Electrical, Electronic and Computer Engineering / unrestricted

Amphibians have been facing global declines over the last decades due to direct and indirect effects of anthropogenic activities. One of the leading causes is environmental contamination, particularly that of waterbodies which are used by many amphibian species for reproduction, development, and adult life. An important source of contamination comes from agricultural runoffs of pesticides such as neonicotinoids, which are known to alter anuran survival, behaviour, predation stress response, and development. However, few studies have investigated the possible interactions between neonicotinoids and natural environmental stressors which could alter the strength and direction of observed neonicotinoid effects. This study investigated how a concentration of imidacloprid (a neonicotinoid) measured in surface waters interacted with high population density, an important environmental stressor, to influence behaviour and development across metamorphosis in wood frogs (Lithobates sylvaticus) known to breed in agricultural landscapes. I reared tadpoles in a fully crossed design experiment, between two densities (0.33 and 1 tadpole/L) and clean vs contaminated water (10 µg/L imidacloprid). Behaviours were measured in the absence and presence of predation cues using open-field tests at three distinct developmental stages, up to the metamorph stage. I found that imidacloprid did not interact with population density or independently affect behaviours in the absence of predation cues. However, individuals raised at high density compared with low density were more active at an early developmental stage but less active at metamorphic climax. Furthermore, both density and imidacloprid independently decreased the natural behavioural response (i.e., “freezing”) of tadpoles to predation cues. Both treatments also slightly accelerated metamorphosis while only density altered final mass at metamorphosis. Finally, I found that distance travelled was weakly repeatable between aquatic stages but not repeatable across metamorphosis, a pattern that was not affected by treatments. This study provides novel insights on the ecotoxicology of imidacloprid in the presence of a natural stressor, highlighting the importance of including behavioural assays and stressors in studies of amphibian ecotoxicology.

This thesis aims to contribute to the field of interaction design by exploring the use of nonverbal cues in FTF communication with the aim of generating knowledge that can be used as an alternative approach for assessing and designing text-based CMC media. To achieve this goal, movement in is analysed in the nonverbal and collaborative dimensions of FTF communication. This presents the possibility to assess text-based CMC media based on a better understanding of the use of nonverbal cues and FTF communication as a standard. The assessment and design based on this concept is tested in the design phase. This process provides a platform for discussion and evaluation of an alternative approach for designing text-based CMC media with a focus on interaction between communicators.

Studying the field of visual attention in the context of games can help level designers to make the players feel more immersed and increase the general enjoyment of a game. With the help of visual cues, the designers are able to lead the players through the levels without breaking the aesthetics of the game, thus preventing to break the immersion. This study is presenting a method for analyzing visual cues in a 3D adventure platform game. Gathering data with the help of today's eye-tracking technology. The results can ultimately be used as a guideline for future work in the field.

This study was an exploration of adults with long-term hearing loss (LTHL) and how it may relate to social intelligence (SI) proficiency. The outcome of this study was intended to illuminate a gap in the literature, namely, the manner in which those with long-term LTHL were able to understand social situations and communicate with others when auditory comprehension was limited. A quantitative nonexperimental method was used that provided the Tromso Social Intelligence Scale (TSIS) to a group of 66 adults with LTHL who were diagnosed with hearing loss as children, as well as a group of 70 adults with no discernable hearing loss (NDHL). The TSIS was used to determine if those with LTHL would have scored higher on the total scale score and the subscales of social information processing and social awareness, than would those with NDHL. The results of the study were determined by an independent t test. There was no significant difference in the total scale and subscale scores between LTHL and NDHL for this relatively small samples study. These findings could aid the hearing loss community at large through a focus on SI skills to improve confidence and communication for those with LTHL. One social change benefit of this study demonstrates that SI for people with LTHL is comparable to people with NDHL. Such a finding suggests that while people with LTHL did not rate higher in SI, they also are not impaired in social situations because of their hearing loss.

This study utilized the theories of David C. McClelland and associates regarding affective arousal, concept of cues arousing motives, and neutral testing procedures. The problem was to study the influence of color and/ or movement, as cues added to the McClelland four-picture Thematic Apperception Test, to evoke need achievement responses to determine whether or not the added stimuli of color and/or movement might evoke increased need achievement responses. Four treatment variations of the test were made: Treatment A, consisted of the standard McClelland test, in black and white pictures. This treatment served as the control. Treatment B used the black and white pictures, but with movement added to the standard test. Treatment C added color to the pictures, but no movement. Treatment D added both color and movement to the test. A special effects apparatus was used to create the color and/or movement added to the pictures. The treatment variations of the four pictures were recorded on motion picture film in order to standardize the experimental procedures of the study. A sample of 120 male college students was tested, and subdivided into groups of 30 subjects each. Each group of 30 students saw only one of the four treatment variations. The testing was accomplished by projecting the filmed, four-picture McClelland test, with each of the four pictures being shown for 20 seconds. After each picture was shown, five minutes were allowed for the subjects to write a story about the picture. The stories were scored for need achievement by the McClelland and associates (1953) scoring system C. Statistical comparisons were made among the three experimental groups (Treatment B, C, D), as compared with the control group (Treatment A) in terms of the subject's mean scores in need achievement. No significant differences were found in any of the statistical comparisons. It was, therefore, concluded that the study subjects did not respond to the addition of color and/or movement as significant cues related to achievement motivation.

The federally endangered June sucker (Chasmistes liorus mictus), which is endemic to Utah Lake, UT, historically spawned in all significant tributaries flowing into Utah Lake. However, due to a variety of anthropogenic changes, June sucker spawning is now primarily restricted to the Provo River, the largest tributary to Utah Lake. The purpose of this study was to gain a better understanding of the spawning and early life history of the June sucker. My specific objectives were to determine (1) what environmental factors attract or deter June suckers to certain Utah Lake tributaries for spawning; (2) what cues June suckers to migrate upstream to spawn; (3) if June suckers use more than one tributary for spawning; and (4) what limiting factors exist in these smaller tributaries. I performed weekly trap-netting surveys and installed passive integrated transponder tag interrogation systems into five Utah Lake tributaries during the spring of 2008 to determine if suckers were using multiple tributaries for spawning and to determine the timing and number of fish migrating upstream to spawn. I coupled the trap-netting data (staging) and migration data (tributary use) with a suite of biotic and abiotic environmental variables in a random forest model to establish the strongest relationships that exist between fish migration and environmental factors. I found that June sucker were present at the mouths of all tributaries sampled and migrated up three of the five tributaries during the spawning season. The Provo River was the tributary most used. Evidence of reproduction was found in four of the five tributaries by the presence of larval June sucker. The random forest model, for staging, indicated that lower total dissolved solids of the tributaries influenced higher catch per unit effort at the mouths of the tributaries, but explained only 33% of the variance. The random forest model, for tributary use, performed very well, explaining 85% of the variance and indicated discharge was the most important variable for upstream migration. Specifically, the ascending limb of the hydrograph appeared to cue migration and the descending limb cue spawning. I also found the most likely limiting factors in the smaller tributaries are degraded water quality and available spawning habitat. Results from this study show fish are selecting less degraded streams for spawning. Stream restoration projects, in the smaller tributaries, would likely increase the spawning habitat for June suckers and aid their recovery.

No description available.

No description available.

Accurate and usable x-ray vision has long been a goal in augmented reality (AR) research and development. X-ray vision, or the ability to comprehend location and object information when such is viewed through an opaque barrier, would be imminently useful in a variety of contexts, including industrial, disaster reconnaissance, and tactical applications. In order for x-ray vision to be a useful tool for many of these applications, it would need to extend operators’ perceptual awareness of the task or environment. The effectiveness with which x-ray vision can do this is of significant research interest and is a determinant of its usefulness in an application context. In substance, then, it is crucial to evaluate the effectiveness of x-ray vision—how does information presented through x-ray vision compare to real-world information? This approach requires narrowing as x-ray vision suffers from inherent limitations, analogous to viewing an object through a window. In both cases, information is presented beyond the local context, exists past an apparently solid object, and is limited by certain conditions. Further, in both cases, the naturally suggestive use cases occur over action space distances. These distances range from 1.5 to 30 meters and represent the area in which observers might contemplate immediate visually directed actions. These actions, simple tasks with a visual antecedent, represent action potentials for x-ray vision; in effect, x-ray vision extends an operators’ awareness and ability to visualize these actions into a new context. Thus, this work seeks to answer the question “Can a real window be replaced with an AR window?” This evaluation focuses on perceived object location, investigated through a series of experiments using visually directed actions as experimental measures. This approach leverages established methodology to investigate this topic by experimentally analyzing each of several distinct variables on a continuum between real-world depth perception and fully realized x-ray vision. It was found that a real window could not be replaced with an AR window without some loss of depth perception acuity and accuracy. However, no significant difference was found between a target viewed through an opaque wall and a target viewed through a real window.