Zheng, Dang Cong (University of Wolverhampton, 2011)
Accent conversion intends to change the accent of a speaker to a desired accent and preserve the speaker’s voice identity. This technology can offer a number of useful applications. For example, integrating accent conversion to a text-to-speech system (TTS) can produce a voice with a desired accent instantly and inexpensively. Applying the technology to the film industry can change an actor’s or actress’s accent to a desired accent without hard training for the actor or actress to learn a new accent; this can be achieved by modifying the accent of the film recordings. As a foreign language learning tool, it could allow the learners to listen to their own voice with the native speaker’s accent and to mimic that accent. Hence, enhance learning experience and improve learning progress. In this dissertation, a new approach in both accent analysis and conversion has been proposed. In contrast to previous approaches in accent-related research, such as in regional or foreign accent classification and identification, where the databases are formed from large groups of single-accent speakers, this study uses data from an individual who can speak in two accents. This removes the effects of inter-speaker variability and facilitates efficient identification and analysis of acoustic features of different accents. Two British regional accents which display distinct differences to the human listener were used in this study as two typical British regional accents. Vowel based acoustic analysis was carried out to investigate the acoustic characteristics of the two accents and identify the prominent features that are most influential on the variability of accents. Acoustic characteristics such as formant frequencies, fundamental frequency and its variation slope, intensity of speech, and duration of phone were used for accent acoustic analysis. In this dissertation, accent conversion via formants modification and pitch contour manipulation was investigated. Three different formant-based spectral mappingalgorithms, mean-variance linear conversion, Nth order non-linear conversion and piece-wise linear transformation based on Gaussian mixture model conversion were investigated. Furthermore, the project has implemented accent conversion on a general speech analysis and synthesis system; the output speech synthesized by the three mapping algorithms was assessed by objective and subjective evaluation. The effects of spectral conversion and pitch contour conversion on accent conversion were also evaluated. The results of the study showed that accent conversion can be achieved to some degree via formants modification and pitch contour manipulation.
Cloak, Ross James (University of Wolverhampton, 2011)
Ankle injuries are one of the most common injuries in sport, often leading to functional deficits and instability, a vicious cycle of recurrent sprains and time loss due to injury. Although research has been conducted on the best methods of treating such deficits and instability, new training methodologies are continually being sought to help improve clinical outcomes and with this comes a need for designed research to test such hypotheses. The purpose of the present research was to investigate the effect of vibration training on balance and muscle function in physically active individuals suffering self reported functional ankle instability (FAI). Stage one of the research was to initially investigate the effect of a six week whole body vibration training (WBVT) exercise routine on 38 University dancers reporting FAI. An initial assessment of the severity of the instability was done using the Cumberland Ankle Instability Tool (CAIT), to identify those who classed themselves functionally unstable but still able to participate in their chosen sport. The group was randomly arranged into one of two groups (treatment and control) and a pre/post test study was undertaken, with the control group asked to continue normal activity. The selection of participants was based on instability score from the CAIT. A larger sample of athletes was initially recruited across two accessible sports of football and dance due to access and availability. These groups then completed CAIT and where included if scoring criteria were met. The treatment group undertook six weeks of progressive vibration training on a stabile vibration system. Pre and post testing consisted of measures of static single leg balance, a Star Excursion Balance Test (SEBT) and Electromyography (EMG) of peroneus longus in demi-pointe. Results indicated a significant improvement in static balance (p = .04) and certain SEBT directions within the treatment group compared to the control group (p <.05). Neither group reported any significant difference in mean power frequency for the peroneus longus (p >.05). The results of the study suggested six weeks vibration training improved certain balance parameters within FAI populations. These results although initially encouraging, identified the need for further research with not just a direct comparison between treatment and control, but a closer examination of the effect of vibration training in comparison to more classical methods of rehabilitation before it can be recommended as a serious methods of treatment for FAI. The second stage of the research involved the implementation of a new piece of rehabilitation equipment which combined a vibration unit within a wobble board (Vibrosphere TM, Sweden). The manufactures claim the combination of the two principles accelerates rehabilitation for numerous lower body injuries and disorders. This specially designed unit allowed direct analysis of the effect of the vibration component of the unit on balance and muscle function, by comparing those who used the combined vibration/wobble board and those who simply used the wobble board alone. A control group was also included to analyse any difference over time as the testing was done during a pre-season training cycle. The research consisted of 33 semi-professional footballers reporting FAI as confirmed by CAIT and taler tilt and an anterior drawer test, being randomly assigned to one of three groups; Vibration/wobble board, Wobble board alone and Control. Both Vibration/wobble board and Wobble board alone completed identical exercises on identical equipment so results could not be attributed to different equipment. The results of the study suggest a significant difference in static balance; modified SEBT and Single leg triple hop for distance between groups with the greatest improvement being within the combined vibration/wobble board group (p <.05). The results suggest the combination of vibration and wobble board improve balance and functional strength in those footballers reporting FAI compared to wobble board training alone. The precise mechanisms behind the current results are unclear. It has been suggested that it may be due to vibration having a positive effect on the stimulation of mechanoreceptors and the combination of that and unstable surface control seems to be optimal. It is difficult to compare studies but the research has highlighted certain areas for further research. The difference in static balance and SEBT scores between the dancers and footballers seems to suggest that the CAIT scores although similar may identify the need for more specific tests for each population. Also a longitudinal study is required to access injury rates following intervention and effect duration of the improvements seen.
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