Objetivos - A Neurografia por ressonância magnética (RM) tem sido usada para avaliar estruturas nervosas (nervos e plexos nervosos) por proporcionar melhor contraste entre essas estruturas e os tecidos circundantes. O objetivo deste estudo é investigar a reprodutibilidade do uso da neurografia pela técnica de difusão por ressonância magnética (DW-MR) para avaliar o plexo lombar no planejamento de artrodese com acesso lateral transpsoas. Outro objetivo é avaliar se a frequência em que os ramos do plexo lombar são encontrados nas diferentes zonas nos interespaços L3-4 e L4-5 é alterada quando do uso de diferentes espessuras de retratores cirúrgicos. Métodos Noventa e quatro pacientes (188 plexos lombares) com dor lombar e doenças degenerativas da coluna foram submetidos a DW-MR do plexo lombar relativa aos espaços discais L3-4 e L4-5, e terço superior do corpo vertebral de L5. As imagens foram reconstruídas no plano axial, com cortes de alta resolução de 10 mm de espessura sobre o espaço discal e de 22 mm em L3-4 e L4-5, simulando a zona de trabalho de retratores usados de rotina no acesso transpsoas. As posições da raiz de L4 e do nervo femoral foram analisadas em relação ao disco L4-5 e confirmadas nos planos sagitais. Radiologista e um cirurgião de coluna experiente realizaram as avaliações das imagens de forma às cegas e independente. Para aferir o grau de concordância intra e interobservadores aplicamos o teste de Kappa. Resultados. O plexo lombar foi identificado com êxito em todos os pacientes. Em L3-4, todos, os componentes do plexo (exceto o nervo genitofemoral) foram localizados no quadrante mais posterior do espaço discal (zona IV), exceto em um caso. As raízes de L3 e de L4 coalesceram-se no nervo femoral abaixo do espaço discal L4-5 em todos os sujeitos. Variação lado a lado foi observada, estando o plexo localizado na zona IV em 86,2% pacientes à direita e 78,7 % à esquerda. No terço superior de L5, o plexo foi encontrado na zona III em 27,7 % à direita e em 36,2% à esquerda; e na zona II em 4,3% à direita e em 2,1% à esquerda. Encontramos uma concordância substancial intra e interobservadores (com valores de Kappa entre 0,6 e 0,79, para o índice de concordância intra e interobservador, nos grupos de 10 e 22 mm em ambos os lados). Conclusão: O mapeamento pré-operatório do plexo lombar por meio da neurografia por DW-MR se mostrou reprodutível intra e intraobservadores e, portanto, tem potencial para melhorar o perfil de segurança dos procedimentos por acesso lateral. / Purpose - Magnetic resonance (MR) neurography has been used to evaluate entire nerves and nerve bundles by providing better contrast between the nerves and the surrounding tissues. The purpose of the study was to validate diffusion-weighted MR (DW-MR) neurography in visualizing the lumbar plexus during preoperative planning of lateral transpsoas surgery. Methods - Ninety-four (188 lumbar plexuses) spine patients underwent a DW-MR examination of the lumbar plexus in relation to the L34 and L45 disc spaces and superior third of the L5 vertebral body. Images were reconstructed in the axial plane using high-resolution Maximum Intensity projection (MIP) overlay templates at the disc space and L34 and L45 interspaces. 10 and 22 mm MIP templates were chosen to mimic the working zone of standard lateral access retractors. The positions of the L4 nerve root and femoral nerve were analyzed relative to the L45 disc in axial and sagittal planes. Third-party radiologist and a senior spine surgeon performed the evaluations, with inter- and intraobserver testing performed (Kappa test). Results - In all subjects, the plexus was successfully mapped. At L34, in all but one case, the components of the plexus (except the genitofemoral nerve) were located in the most posterior quadrant (zone IV). The L3 and L4 roots coalesced into the femoral nerve below the L45 disc space in all subjects. Side-to-side variation was noted, with the plexus occurring in zone IV in 86.2 % right and only 78.7 % of left sides. At the superior third of L5, the plexus was found in zone III in 27.7 % of right and 36.2 % of left sides; and in zone II in 4.3 % right and 2.1 % left sides. Significant inter- and intraobserver agreement was found. (Kappa test values ranging from 0,6 to 0,79, for intra and interobserver concordance index, in 10 and 22 mm groups, both sides). Conclusions - By providing the surgeon with a preoperative roadmap of the lumbar plexus, DW-MR may improve the safety profile of lateral access procedures.

Objetivo: verificar a razão extensores/flexores dos músculos cervicais no âmbito de força muscular e atividade eletromiográfica durante a mensuração da força na contração isométrica voluntária máxima (CIVM) e teste de flexão craniocervical (TFCC) em pacientes com migrânea e em indivíduos sem cefaleia. Além de verificar o desempenho muscular, avaliado pelo TFCC, em ambos os grupos. Materiais e métodos: foram incluídas 52 mulheres com diagnóstico de migrânea segundo a Classificação Internacional de Cefaleias e 52 mulheres sem histórico de cefaleia ou dor cervical com idade entre 18 e 55 anos. No grupo migrânea os questionários Neck Disability Index, Migraine Disability Assessment e 12-item Allodynia Symptom Checklist foram aplicados. Em ambos os grupos a força dos músculos flexores e extensores cervicais foi avaliada utilizando-se um dinamômetro manual (Lafayette Instrument Company®, Lafayette, IN, USA). A CIVM foi mantida por 3 segundos e foram realizadas 3 repetições. Além do teste de força, o TFCC também foi realizado para os dois grupos utilizando-se o dispositivo de pressão Stabilizer Pressure Biofeedback® (Chatanooga, Hixson, TN, USA). O dispositivo, incialmente, foi inflado a 20 mmHg e a participante deveria aumentar 2 mmHg a cada estágio, totalizando cinco estágios (30 mmHg), e manter a pressão por 10 segundos. Em ambos os testes, para os dois grupos, a atividade eletromiográfica dos músculos cervicais foi avaliada por meio de sensores de superfície sem fio (TrignoTM Wireless System, Delsys Inc. Boston, MA). Resultados: observamos que o grupo migrânea apresenta uma redução na força dos músculos flexores em comparação ao grupo controle e consequentemente, uma maior razão de força dos músculos extensores/flexores além de uma reduzida razão eletromiográfica dos músculos extensores/flexores durante a CIVM em flexão. Nossos resultados demonstraram ainda uma pior performance no TFCC no grupo migrânea e consequente aumento da razão eletromiográfica dos músculos extensores/flexores cervicais no último estágio do teste. Conclusão: de acordo com os nossos resultados podemos concluir que mulheres com migrânea apresentam um notável desequilíbrio dos músculos flexores e extensores cervicais em comparação a controles não apenas na produção de força, mas também na atividade muscular. / Objective: To verify the extensor/flexor ratio of neck muscle strength and electromyographic activity at maximal voluntary isometric contraction (MVIC) and at the craniocervical flexion test (CCFT) of patients with migraine and of individuals with no history of headache. In addition, we aimed to assess the performance of both groups at the CCFT. Materials and methods: Fifty-two women with a diagnosis of migraine according to the International Classification of Headache Disorders and 52 women without history of migraine or cervical pain with ages between 18 and 55 years were included. The Neck Disability Index, Migraine Disability Assessment and 12-item Allodynia Symptom Checklist questionnaires were applied to the migraine group. In both groups, cervical muscle strength was assessed during a MVIC using a hand-held dynamometer (Lafayette Instrument Company®, Lafayette, IN, USA). The MVCI was maintained for 3 seconds and 3 repetitions were performed. The CCFT was also performed by the two groups using the Stabilizer Pressure Biofeedback® (Chatanooga, Hixson, TN, USA). The device was initially inflated to 20 mmHg and the participant had to increase 2 mmHg at each stage, achieving five stages (30 mmHg), and maintaining the pressure for 10 seconds. In both tests, the electromyographic activity of the cervical muscles was evaluated using wireless surface sensors (TrignoTM Wireless System, Delsys Inc. Boston, MA). Results: migraine group has a reduction in flexor muscle strength compared to the control group and consequently a greater muscle strength ratio of extensor/flexor and a reduced electromyographic ratio of the extensor/flexor muscles during MVIC in flexion. Our results also demonstrated a worse performance in the CCFT in the migraine group and consequent increase in the electromyographic ratio of the extensor/flexor neck muscles in the last stage of the test. Conclusion: women with migraine present a remarkable imbalance of the flexor and extensors cervical muscles compared to controls not only in the production of strength but also in muscle activity.

De acordo com o conceito de cadeia cinética, o controle da posição distal depende da estabilização dos segmentos proximais. Deste modo, a estabilização necessária para o controle e movimento dos membros superiores é proporcionada pelo tronco e pela pelve que servem como meio de transmissão de força e energia. O controle da postura e do movimento é realizado por mecanismos de feedback e feedforward definidos pela teoria do controle motor. O feedforward é descrito pelas atividades antecipatórias corporais a fim de neutralizar os efeitos perturbadores de determinada condição específica. O feedback é representado pelo uso do biofeedback (estímulo verbal, visual, auditivo ou cinestésico) com o objetivo de restaurar a coordenação e o controle muscular, e potencializar os mecanismos de feedforward muscular. Há poucas investigações de tais mecanismos de controle no complexo articular do ombro e estudos prévios demostram a influência de comandos verbais para a orientação escapular sobre os padrões de ativação muscular seletiva do ombro. Objetivo: verificar o efeito da instrução verbal para ativação consciente da musculatura abdominal, sobre a atividade dos músculos periescapulares em pacientes com sintomas da síndrome do impacto no ombro durante exercícios de força. Materiais e Métodos: 30 voluntários com condição dolorosa há pelo menos 4 semanas no ombro, de ambos os sexos ( 11 homens e 19 mulheres) com idade de 35 a 75 anos realizaram exercícios para o complexo sendo que o grupo controle apenas repetiu os exercícios já o outro grupo recebeu treinamento para adicionar a contração abdominal consciente referente a estímulo verbal e tátil durante os mesmos exercícios previamente realizados, assim o sinal eletromiográfico foi captado através do aparelho TrignoTM Wireless System (Delsys Inc. Boston, MA). Resultados: Durante os exercícios a comparação entre grupos com e sem instrução para contração abdominal no momento pré e pós apresentou diferença no modelo linear de efeitos mistos apenas para os músculos Trapézio Transverso durante o Full can (FC) para o lado sintomático (TE:0,92); Trapézio ascendente para o lado 10 sintomático durante (FC) (TE:-0,96) e para o lado assintomático durante External Rotation Kneeling (ERK) (TE:-0,81); já o Serrátil anterior quando exigido no exercício Knee Push (KP) o lado assintomático apresentou diferença entre os grupos (TE:-1,24) assim como no (ERK) com (TE: -2,09) para lado assintomático e no Wall Slide with Towel (WST) com (TE:1,03) também para o lado assintomático; Conclusão / According to the kinetic chain concept, the control of the distal position depends on the stabilization of the proximal segments. Thus, the stabilization necessary for the control and movement of the upper limbs is provided by the trunk and pelvis which serve as a means of transmitting force and energy. The control of posture and movement is performed by feedback and feedforward mechanisms defined by motor control theory. Feedforward is described by anticipatory body activities in order to counteract the disruptive effects of a particular condition. The feedback is represented by the use of biofeedback (verbal, visual, auditory or kinesthetic stimulus) with the objective of restoring coordination and muscular control, and potentiate the mechanisms of muscle feedforward. There are few investigations of such control mechanisms in the shoulder joint complex and previous studies demonstrate the influence of verbal commands on the scapular orientation on selective muscular activation patterns of the shoulder. Objective: To verify the effect of verbal instruction for conscious activation of the abdominal musculature on the activity of the periescapular muscles in patients with symptoms of shoulder impact syndrome during strength exercises. Materials and Methods: 30 volunteers with painful condition for at least 4 weeks on the shoulder, of both sexes (11 men and 19 women) aged 35 to 75 years performed exercises for the complex and the control group only repeated the exercises already the other group received training to add conscious abdominal contraction regarding verbal and tactile stimuli during the same exercises previously performed, so the electromyographic signal was captured through the TrignoTM Wireless System (Delsys Inc. Boston, MA). Results: During the exercises, the comparison between groups with and without instruction for abdominal contraction at the pre and post moments presented a difference in the linear mixed effects model only for Middle trapezoid muscles during Full can (FC) for the symptomatic side (TE: 0.92 ); trapeze lower to the symptomatic side during (FC) (TE: -0.96) and to the asymptomatic side during External Rotation Kneeling (TE: -0.81). The anterior serratus when required in the Knee Push exercise (KP), the asymptomatic side presented a difference between the groups (TE: -1.24) as well as in the (ERK) with (TE: -2.09) for asymptomatic side and Wall Slide with Towel (WST) with (TE: 1.03) also for the asymptomatic side; Conclusion:

Cheung Chi-Kin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 53-60). / Text in English; abstracts in English and Chinese. / Cheung Chi-Kin. / Acknowledgement --- p.i / Abstract --- p.ii / Table of Contents --- p.v / List of Figures --- p.viii / List of Tables --- p.ix / Introduction --- p.1 / Statement of Problem --- p.3 / Research Questions --- p.4 / Significance of the Study --- p.4 / Theoretical contribution --- p.4 / Practical contribution --- p.5 / Review of Literature --- p.6 / Physiological Studies regarding Load Carriage --- p.6 / Energy expenditure --- p.7 / Heart rate --- p.7 / Comparison between physiological studies and biomechanical studies regarding load carrying --- p.8 / Motor Control during Load Carrying --- p.10 / Gait Pattern --- p.11 / Gait pattern under load carrying --- p.11 / Walking velocity --- p.13 / Treadmill vs. overground walking --- p.13 / Trunk Posture --- p.15 / Electromyographic Activity --- p.16 / EMG and muscle force --- p.17 / EMG and fatigue --- p.18 / EMG during load carrying --- p.19 / Load Carrying Studies in Children --- p.21 / Methodology --- p.24 / Design --- p.24 / Subject --- p.24 / Instrumentation --- p.25 / Motion analysis --- p.25 / Electromyography --- p.25 / Heart rate measurement --- p.26 / School bag --- p.26 / Experimental Set-up --- p.27 / Procedures --- p.27 / Data Reduction --- p.29 / Gait parameters --- p.29 / Trunk posture --- p.31 / Electromyographic analysis --- p.32 / Heart rate --- p.34 / Data Analysis --- p.34 / Results --- p.35 / Gait Pattern --- p.35 / Trunk Posture --- p.36 / Electromyographic Activity --- p.37 / Channel 1 --- p.37 / Channel 2 --- p.37 / Channel 3 --- p.38 / Heart Rate --- p.38 / Summary --- p.39 / Discussion --- p.40 / Gait Pattern during Load Carriage --- p.40 / Stride parameters --- p.40 / Temporal parameters --- p.42 / Trunk Posture --- p.43 / Electromyographic Activity --- p.44 / Erector spinea --- p.45 / Upper trapezius --- p.45 / Risk factor from EMG measurement --- p.47 / Heart Rate --- p.47 / Maximum Permissible Backpack Weight for Children --- p.48 / Limitations of the Study --- p.49 / Further Direction --- p.50 / Conclusion --- p.52 / References --- p.53 / Appendix / Appendix A - Subject Information & Consent form --- p.61 / Appendix B - Experiment Set-up --- p.66 / Appendix C - Measurement of Skinfold --- p.67 / Appendix D - Standardized Isometric Maximum Voluntary Contraction --- p.68 / Appendix D - Figures and Tables --- p.69

Recently, it became possible to detect single motor units (MUs) noninvasively via the use of spatial filtering electrode arrays. With these arrays, weighted combinations of monopolar electrode signals recorded from the skin surface provide spatial selectivity of the underlying electrical activity. Common spatial filters include the bipolar electrode, the longitude double differentiating (LDD) filter and the normal double differentiating (NDD) filter. In general, the spatial filtering is implemented in hardware and the performance of the spatial filtering apparatus is measured by its common mode rejection ratio (CMRR). High precision hardware differential amplifiers are used to perform the channel weighting in order to achieve high CMRR. But, this hardware is expensive and all channel weightings must be predetermined. Hence, only a few spatially filtered channels are typically derived. In this project, a distinct software equalization filter was cascaded with each of the hardware monopolar signal conditioning circuits to achieve accurate weighting and high CMRR. The simplest technique we explored was to design an equalization filter by dividing the frequency response of a“reference" (or“ideal") channel by the measured frequency response of the channel being equalized, producing the desired equalization filter in the frequency domain (conventional technique). Simulation and experimental results showed that the conventional technique is very sensitive to broadband background noise, producing poor CMRR. Thus, a technique for signal denoising that is based on signal mixing was pursued and evaluated both in simulation and laboratory experiments. The purpose of the mixing technique is to eliminate the noise as much as possible prior to equalization filter design. The simulation results show that without software equalization, CMRR is only around 30 dB; with conventional technique CMRR is around 50~60 dB. By using mixing technique, CMRR can be around 70~80 dB.

In performing manual tasks, muscles are voluntarily contracted in order to produce force and orient the limb in the desired direction. Many occupational tasks are associated with frequent musculoskeletal disorders. In tasks involving skilful manipulation, very frequently the forces are focused on the upper limb and neck. Upper extremity cumulative trauma disorders are among the more common worker related injuries. These muscle disorders may be related to repetitive exertions, excessive muscle loads and extreme postures. One of the major challenges is to quantify the muscle load and researchers have tried various measures to quantify muscle load. Joint mechanical impedance can be a robust method to quantify muscle load. Joint mechanical impedance characterizes the dynamic torque-angle relationship of the joint. Joint impedance has been measured by earlier researchers, for limited tasks, by imparting force (or angle) perturbations on the joint and relating resultant angular (or force) changes. The joint impedance gives a quantitative measure related to muscle co-contraction level. Measurement of the mechanical impedance at the workplace may provide useful information relevant to the understanding of upper limb disorders. Electromyogram (EMG) is the electrical activity of the muscle. Usually, an estimate of the EMG amplitude is obtained from the raw waveform recorded from the surface of the skin. EMG amplitude estimates can be used to non-invasively estimate torque about joints. Presently, there exists no means by which mechanical impedance can be estimated non-invasively (i.e., without external perturbations). Therefore, we proposed the use of EMG to noninvasively estimate the joint mechanical impedance. Our objective in this project was to determine the extent to which surface EMG can be used to estimate mechanical impedance. Simulation studies were first performed to understand the extent to which this tool could be useful and to determine methods to be used for the experiment. The simulations were followed by evaluating and estimating mechanical impedance using data collected from one experimental subject. Simulations helped to devise processing techniques for the measured signals and also to determine the length of data to be collected. Low pass filters for derivatives (used in the development of impedance estimates) were designed. Subtracting out a polynomial was the best approach to attenuate a low frequency drift (artifact) that occurs in torque measurements. Thirty seconds of data provided impedance estimates with a relative error of 5% when EMG amplitude estimates with SNR of 15 were used. Experimental data from constant-posture, slowly force-varying background torque level showed that the elbow joint system behaved like a second order linear system between 2 Hz and 10 Hz. Co-contraction by subjects during experiments caused impedance estimates to be unexpectedly high even at low background torque. Further experiments would need to be conducted with the subjects being instructed to avoid co-contraction.

O objetivo do presente estudo foi de analisar as respostas de ativação muscular e força de reação do solo de um exercício de hidroginástica com diferentes equipamentos, executado por mulheres jovens. Sendo assim, foram realizados três testes progressivos máximos em ambiente aquático, com no mínimo 48 horas de intervalo, com o exercício de chute, sem equipamento (SE), com equipamento resistivo (RE) e flutuante (FL), a fim de determinar a cadência correspondente ao segundo limiar ventilatório (LV2). O terceiro e último dia de testes consistiu primeiramente na contração voluntária isométrica máxima (CVM) em ambiente terrestre, dos músculos a serem avaliados: reto femoral (RF), bíceps femoral (BF), tibial anterior (TA) e gastrocnêmio lateral (GA). Após finalizada a CVM de cada músculo, foi feito um isolamento dos eletrodos, e então o sujeito entrou na piscina para realizar os testes de eletromiografia (EMG) e força de reação do solo (FRS) nas intensidades do LV2 e máximo esforço (MAX). Dentro da piscina, o sujeito foi posicionado na profundidade do processo xifóide e então, executou as três situações do exercício de chute (SE, RE e FL), de forma randomizada, nas intensidades LV2 e máximo esforço (MAX). Foi utilizada o teste estatístico de Equações estimativas generalizadas e o teste post-hoc de Bonferroni. Após o tratamento dos dados e análise estatística, foram encontrados maiores valores de ativação muscular da intensidade LV2 para MAX, para todas as situações nos músculos RF, BF e TA, exceto para GL que não obteve diferenças entre intensidades para a situação RE. Comparando as situações, não houve diferenças significativas entre as mesmas para RF, BF e TA, exceto para o músculo GLque obteve menores valores de ativação para a situação RE comparada à SE. Para os resultados de FRS, foram encontrados maiores valores para a intensidade MAX para as situações SE e RE, enquanto para FL, não foram encontradas diferenças de FRS entre as intensidades. Comparando as situações, FL obteve menores valores comparado à SE e RE, nas duas intensidades. Para os resultados de impulso (IMP), foram encontradas diferenças significavamente menores para a intensidade MAX para todas as situações, com menores valores de IMP na situação FL. A partir dos resultados encontrados no 6 presente estudo, de uma maneira geral, a utilização de equipamentos tanto RE quanto FL, parece não influenciar a ativação muscular durante a execução do exercício CH, além disso, a intensidade MAX elicita maiores valores de ativação. Além disso, apesar de terem sido encontradas diferenças de FRS e IMP entre as intensidades, o equipamento FL obteve menores valores de FRS e IMP, sem diferenças entre LV2 e MAX na FRS, demonstrando que apesar de obter uma maior ativação muscular em MAX, não houve um aumento significativo de FRS nesta intensidade. Sendo assim, a utilização de equipamentos parece influenciar principalmente a variável de FRS, reduzindo estes valores e tornando o exercício de CH mais seguro quando é necessária uma menor sobrecarga articular, enquanto a ativação muscular não se difere das outras situações. / The aim of the presente study was to analyze the muscle activation and ground reaction forces responses of one hydrogymnastic exercise performed by women with different devices. Three sessions of water progressive testes were conducted with 48 hours of interval with the frontal kick exercise (FK) without devices (WD), with resistance devices (RD) and floating devices (FD), to determine the cadence corresponding to the second ventilatory threshold (VT2).The third and last day of tests consisted iniciated with the maximum voluntary contraction (MVC) of the muscles to be analyzed: rectus femoris (RF), biceps femoris (BF), tibialis anterior (TA) and gastrocnemius lateralis (GL). After that, the electrodes were isolated and than the subject entered the pool (immersion on the xifoide process) to perform the electromiography (EMG) and ground reaction forces (GRF) tests in VT2 and maximum (MAX) intensity. Generalized estimating equation and Bonferroni’s test were used for the statistical analyses. The results showed higher muscle activity for the MAX comparing to VT2 for RF, BF and TA, except for GL muscle, which didn’t achieve difference between the intensities for RD. Comparing the three situations, there was no significant difference between. In VT2 and MAX there was no difference between all situations, except for GL in MAX, which obtained lower values for RD compared with FD. The ground reaction forces results showed higher values for the MAX intensity for the WD and RD situations, while for FD there was no difference between VT2 and MAX. Comparing the situations, FD obtained lower values compared with WD and RD in both intensities. For impulse (IMP), significant lower values were founde for the MAX intensity for all situations, with lower values for FD. According to the results, it might be concluded that the use of devices seems to not influence the muscle activity during the FK exercise, besides that, the MAX intensity elicits higher results. Despite the differences for GRF and IMP, the FL situation leads to a higher muscle activation in MAX while there is no GRF increase from VT2. Therefore, the use of devices appears to influence mostly the GRF variable, showing lowest values for this situation comparing to WD and RD making FK safer when a lower joint overload is needed, while the muscle activation didn’t differ from WD and RD.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Vita. / Bibliography: leaves 181-187. / by Ronald Stanton LeFever. / Ph.D.

A method for synthesizing speech from surface electromyogram (SEMG) signals in a frame-by-frame basis is presented. The input SEMG signals of spoken words are blocked into frames from which SEMG features were extracted and classified into a number of phonetic classes by a neural network. A sequence of phonetic class labels is thus produced which was subsequently smoothed by applying an error correction technique. The speech waveform of a word is then constructed by concatenating the pre-recorded speech segments corresponding to the phonetic class labels. Experimental results show that the neural network can classify the SEMG features with 86.3% accuracy, this can be further improved to 96.4% by smoothing the phonetic class labels. Experimental evaluations based on the synthesis of eight words show that on average 92.9% of the words can be synthesized correctly. It is also demonstrated that the proposed frame-based feature extraction and conversion methodology can be applied to SEMG-based speech synthesis. / Although speech is the most natural means for communication among humans, there are situations in which speech is impossible or inappropriate. Examples include people with vocal cord damage, underwater communications or in noisy environments. To address some of the limitations of speech communication, non-acoustic communication systems using surface electromyogram signals have been proposed. However, most of the proposed techniques focus on recognizing or classifying the SEMG signals into a limited set of words. This approach shares similarities with isolated word recognition systems in that periods of silence between words are mandatory and they have difficulties in recognizing untrained words and continuous speech. / Lam Yuet Ming. / "December 2006." / Adviser: Leong Heng Philip Wai. / Source: Dissertation Abstracts International, Volume: 68-08, Section: B, page: 5392. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 104-111). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Thesis. 1976. M.S.--Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics. / Microfiche copy available in Archives and Barker. / Bibliography: p.80-81. / M.S.