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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Developing Heuristics to Optimize the Configuration of the Video-Mediated Environment

Grenville, N. Delia 08 May 2001 (has links)
A study was conducted to determine the preferences for the design of distributed meeting rooms used for video enhanced electronic meeting systems (VEMS). Although there is a significant body of literature in the group communication domain, the research in this multidisciplinary area has paid minimal attention to users' environmental preferences in the design of a meeting space. A basic science approach through three studies was used to explore the variables that defined the design of a distributed meeting space from the user's perspective. Twenty-five inexperienced college-enrolled participants and twenty-five experienced Naval professionals used foam-core pieces to create a design of their ideal distributed meeting space. Thirty-seven variables were used to categorize qualitative attributes of the designs. Three types of designs emerged from the sample population: v-shaped, conference (u-shaped or oval), and theater (auditorium) style. A nonexperimental design was used to measure the impact of the heuristics on the users' physical design of their distributed meeting spaces. Post-meeting evaluation results were promising and indicated that the heuristics were usable and that participating in the design could have a positive impact on user's subjective rating of their meeting experience. Overall, inexperienced users did not believe that the heuristics were necessary to determine the best room design for their team's needs. In the third study, six experts conducted an expert evaluation of a distributed meeting room site. Most experts were not able to identify context-specific design issues such as camera angle and lighting with the static information that they were provided. The experts subjective ratings indicated that the heuristics were usable and were useful for room designers. The overall findings indicated that experience level had a significant impact on user's perception of important equipment in a distributed meeting room. Naïve users were more concerned with visual communication and assigned more importance to public displays (p=.035). Experienced users were more concerned with audio communication and assigned more importance to microphone control (p=.024). In addition, general findings from this research include a new methodology for generating participatory ergonomic tools. / Ph. D.
42

Sound Source Localization and Beamforming for Teleconferencing Solutions

Kjellson, Angelica January 2014 (has links)
In teleconferencing the audio quality is key to conducting successful meetings. The conference room setting imposes various challenges on the speech signal processing, such as noise and interfering signals, reverberation, or participants positioned far from the telephone unit. This work aims at improving the received speech signal of a conference telephone by implementing sound source localization and beamforming. The implemented microphone array signal processing techniques are compared to the performance of an existing multi-microphone solution and evaluated under various conditions using a planar uniform circular array. Recordings of test-sequences for the evaluation were performed using a custom-built array mockup. The implemented algorithms did not show good enough performance to motivate the increased computational complexity compared to the existing solution. Moreover, an increase in number of microphones used was concluded to have little or no effect on the performance of the methods. The type of microphone used was, however, concluded to have impact on the performance and a subjective listening evaluation indicated a preference for omnidirectional microphones which is recommended to investigate further. / God ljudkvalitet är en grundsten för lyckade telefonmöten. Miljön i ett konferens-rum medför ett flertal olika utmaningar för behandlingen av mikrofonsignalerna: det kan t.ex. vara brus och störningar, eller att den som talar befinner sig långt från telefonen. Målet med detta arbete är att förbättra den talsignal som tas upp av en konferenstelefon genom att implementera lösningar för lokalisering av talaren och riktad ljudupptagning med hjälp av ett flertal mikrofoner. De implementerade metoderna jämförs med en befintlig lösning och utvärderas under olika brusscenarion för en likformig cirkulär mikrofonkonstellation. För utvärderingen användes testsignaler som spelades in med en specialbyggd enhet. De implementerade algoritmerna kunde inte uppvisa en tillräcklig förbättring i jämförelse med den befintliga lösningen för att motivera den ökade beräkningskomplexitet de skulle medföra. Dessutom konstaterades att en fördubbling av antalet mikrofoner gav liten eller ingen förbättring på metoderna. Vilken typ av mikrofon som användes konstaterades däremot påverka resultatet och en subjektiv utvärdering indikerade en preferens för de rundupptagande mikrofonerna, en skillnad som föreslås undersökas vidare.
43

Distance education perceptions of satisfaction and critical thinking opportunities among graduate students /

Hilgenberg, Cheryl S. Kennedy, Larry DeWitt, January 1997 (has links)
Thesis (Ed. D.)--Illinois State University, 1997. / Title from title page screen, viewed June 2, 2006. Dissertation Committee: Larry Kennedy (chair), John Goeldi, Barbara Nourie, William Tolone. Includes bibliographical references (leaves 85-90) and abstract. Also available in print.
44

KBT-psykoterapi via videosamtal : Vilka attityder har KBT-behandlare i Sverige till psykoterapi som förmedlas via videolänk? / CBT videoconferencing psychotherapy : CBT clinician’s attitudes towards videoconferencing psychotherapy

Norlin, Mattias January 2020 (has links)
KBT-terapi har de närmaste åren alltmer utförts via videosamtal, även kallat videoconferencing  psychoterapy (VCP) i privat och regional vård i Sverige som spridits ytterligare under pandemin covid-19.  Syftet var att undersöka KBT-behandlares åsikter om VCP. Frågeställningen var ”Vad har KBT-behandlare  för attityder gällande KBT via VCP?”. Ett urval samlades in genom ett bekvämlighetsurval som erhölls genom webenkät. Enkäten spreds via E-post till två KBT-föreningar (BTF och SFKBT) och bland annat  på sociala medier. 140 fullständiga svar gav resultatet att KBT-behandlarna var positiva till VCP som  ansågs tidsbesparande och flexibelt men svårt att motivera vissa patienter till. KBT-tekniker och arbetssätt  som ansågs mer okomplicerat var agenda, behandlingsmål, hemuppgifter, boostersessioner, acceptans och  återfallsprevention. Det ansågs komplexare med känsloreglering, rollspel och exponering. Ångest,  depression och stress ansågs lättare att behandla medan större osäkerhet eller skeptiskhet fanns gällande  tvång, bipolaritet, personlighetssyndrom och fobier. Slutsats blev att VCP ansågs som ett bra sätt att bedriva  KBT med god allians. Kreativa lösningar ansågs behövas för att lösa pedagogiska utmaningar samt att det  ansågs som en utmaning att läsa av kroppsspråk och känsloläge. Vidare forskning krävs för vidare  attitydmätning hos KBT-kliniker. VCP kommer säkerligen vidareutvecklas och expandera vidare. / <p>Linköpings universitet | Institutionen för beteendevetenskap och lärande Psykoterapeutexamensuppsats/magisteruppsats/uppsats på avancerad nivå, 15 hp | Psykoterapeutprogrammet (KBT) Höstterminen 2020 | ISRN-nummer: LIU-IBL/PST-A—20/02—SE</p>
45

The Utilization of Teleconferencing by Community Colleges in Faculty and Staff Development Presentations

Maples, Alan (Alan Royce) 08 1900 (has links)
Members of the Instructional Teleconference Consortium (ITC) were mailed a survey instrument. A total list of 375 teleconference coordinators generated 137 usable responses. The purposes of this study of faculty and staff development presentations by teleconferencing were to determine the amount of usage; which subject areas are utilized; what delivery methods (live, interactive, prerecorded, multimedia, etc.) are utilized; barriers (size or location of college, size of teleconference or travel budget, etc.) to implementing teleconferences; and the sources of presentations utilized in teleconferences. Larger community colleges are the greater users of teleconferencing and even produce some for distribution to other community colleges, whereas smaller community colleges have just begun to receive equipment that enables them to receive telecasts for this purpose. No clear subject area has yet been defined that dominates these teleconferences, and the trend is toward two-way audio and one-way video as the delivery media as communication costs decline. Barriers of money for staff, equipment, and programming appear to be the principal objections to the use of teleconferencing for faculty and staff development presentations. There appear to be few sources of presentations except for the Public Broadcasting System (PBS).
46

System approach to robust acoustic echo cancellation through semi-blind source separation based on independent component analysis

Wada, Ted S. 28 June 2012 (has links)
We live in a dynamic world full of noises and interferences. The conventional acoustic echo cancellation (AEC) framework based on the least mean square (LMS) algorithm by itself lacks the ability to handle many secondary signals that interfere with the adaptive filtering process, e.g., local speech and background noise. In this dissertation, we build a foundation for what we refer to as the system approach to signal enhancement as we focus on the AEC problem. We first propose the residual echo enhancement (REE) technique that utilizes the error recovery nonlinearity (ERN) to "enhances" the filter estimation error prior to the filter adaptation. The single-channel AEC problem can be viewed as a special case of semi-blind source separation (SBSS) where one of the source signals is partially known, i.e., the far-end microphone signal that generates the near-end acoustic echo. SBSS optimized via independent component analysis (ICA) leads to the system combination of the LMS algorithm with the ERN that allows for continuous and stable adaptation even during double talk. Second, we extend the system perspective to the decorrelation problem for AEC, where we show that the REE procedure can be applied effectively in a multi-channel AEC (MCAEC) setting to indirectly assist the recovery of lost AEC performance due to inter-channel correlation, known generally as the "non-uniqueness" problem. We develop a novel, computationally efficient technique of frequency-domain resampling (FDR) that effectively alleviates the non-uniqueness problem directly while introducing minimal distortion to signal quality and statistics. We also apply the system approach to the multi-delay filter (MDF) that suffers from the inter-block correlation problem. Finally, we generalize the MCAEC problem in the SBSS framework and discuss many issues related to the implementation of an SBSS system. We propose a constrained batch-online implementation of SBSS that stabilizes the convergence behavior even in the worst case scenario of a single far-end talker along with the non-uniqueness condition on the far-end mixing system. The proposed techniques are developed from a pragmatic standpoint, motivated by real-world problems in acoustic and audio signal processing. Generalization of the orthogonality principle to the system level of an AEC problem allows us to relate AEC to source separation that seeks to maximize the independence, hence implicitly the orthogonality, not only between the error signal and the far-end signal, but rather, among all signals involved. The system approach, for which the REE paradigm is just one realization, enables the encompassing of many traditional signal enhancement techniques in analytically consistent yet practically effective manner for solving the enhancement problem in a very noisy and disruptive acoustic mixing environment.
47

Multimedia: Perceptions and Use in Preservice Teacher Education

Tennent, Leanne Janene January 2003 (has links)
Across the period in which this research was conducted, there has been an increasing emphasis in government and university policies on the promotion of technology integration in higher education. This emphasis has also become evident in Commonwealth and State government policies relating to preservice teacher education because of the need to ensure that teachers enter the profession with the types of technological skills and competencies that can enhance teaching and learning. The research reported in this thesis describes the experiences and perceptions of computer-based technologies from the perspective of academic staff and graduates from two preservice teacher education courses in a Queensland university. The research was conducted in two phases using a repeated cross-sectional longitudinal design. In Phase 1 of the research conducted in 1997, and in Phase 2 in 2002, questionnaires were used to gather data. In Phase 1 of the research, participants comprised 43 academic staff members involved in two preservice teacher education courses and 72 first or second year graduate teachers from these courses. Items in the academic staff and graduate teacher questionnaires elicited information on a range of issues related to the technologies including knowledge and confidence levels, acquisition of knowledge, current and future usage in teaching, advantages and disadvantages of teaching with the technologies, the importance of the technologies to higher and preservice education and the adequacy of preservice teacher education to prepare new teachers to use technologies. Graduate teachers were also questioned about barriers to their classroom use of technologies. Further questions for academic staff investigated the existence of factors that facilitate usage of technologies and the degree to which the presence or absence of these factors constituted barriers or incentives to technology use. A number of questions also explored attitudes surrounding the valuing of teaching, research and publishing. Results from the first phase of research revealed that both academic staff and new teachers made little use of technologies in their teaching. The most salient barriers to academic staff technology use included lack of technical advice and support, time, and lack of evidence of improved student learning and interest. There was also a widely held perception among academic staff that teaching was not valued by their university and that, in particular, innovation in teaching deserved greater recognition. For graduate teachers, barriers to technology use included lack of computers and resources, lack of school funding, and lack of knowledge and training. In Phase 2 of the research, participants comprised 40 academic staff members and 123 graduate teachers from the same two preservice teacher education courses. Participants were again questioned about knowledge and confidence levels, acquisition of knowledge, current and future usage in teaching, and the adequacy of preservice teacher education to prepare new teachers to use technologies. In light of new research and building on findings from the first phase of data collection, several new questions were added. These questions related primarily to the nature and availability of training and how preservice teacher preparation in technology use could be improved. Results from the second phase of research indicated that, among academic staff and graduate teachers, there had been considerable increases in knowledge and confidence levels in relation to the technologies, along with increased levels of usage. Both groups were also significantly more likely than their earlier counterparts to report that preservice teachers were adequately or well prepared in the use of technologies. For graduate teachers, lack of equipment and resources were ongoing barriers to technology use. Training in technology use appeared to be less of an issue for graduate teachers than academic staff with most reporting access to, and satisfaction with, inservice training opportunities. Encouraging too, was the finding that these graduate teachers were significantly more likely than their 1997 counterparts to attribute their knowledge of the technologies to preservice teacher education. While positive change in technology use was evident across this period, continued efforts to support and integrate technology in preservice teacher education remains important, as does support for the innovative use of technology to promote learning in schools.
48

Voice Activity Detection and Noise Estimation for Teleconference Phones

Eliasson, Björn January 2015 (has links)
If communicating via a teleconference phone the desired transmitted signal (speech) needs to be crystal clear so that all participants experience a good communication ability. However, there are many environmental conditions that contaminates the signal with background noise, i.e sounds not of interest for communication purposes, which impedes the ability to communicate due to interfering sounds. Noise can be removed from the signal if it is known and so this work has evaluated different ways of estimating the characteristics of the background noise. Focus was put on using speech detection to define the noise, i.e. the non-speech part of the signal, but other methods not solely reliant on speech detection but rather on characteristics of the noisy speech signal were included. The implemented techniques were compared and evaluated to the current solution utilized by the teleconference phone in two ways, firstly for their speech detection ability and secondly for their ability to correctly estimate the noise characteristics. The evaluation process was based on simulations of the methods' performance in various noise conditions, ranging from harsh to mild environments. It was shown that the proposed method showed improvement over the existing solution, as implemented in this study, in terms of speech detection ability and for the noise estimate it showed improvement in certain conditions. It was also concluded that using the proposed method would enable two sources of noise estimation compared to the current single estimation source and it was suggested to investigate how utilizing two noise estimators could affect the performance.
49

Experiences of videoconference tutors in instructional methodologies application

Nematandani, Albert Tshamano 02 1900 (has links)
Information and communication technology (ICT) has dominated our lives and the way we learn in such a way that, without it, our way of life becomes obsolete. This study explored challenges experienced by tutors in facilitating teaching and learning through the use of videoconference (VC) technology in an open and distance learning (ODL) environment. These challenges are exacerbated by the fact that most tutors, although highly qualified, do not have teaching methodologies with their qualifications at the time of their employment as tutors. It is believed that if these challenges could be given attention, VC technology would serve as an effective facilitation tool for bridging the distance in teaching and learning. Based on qualitative research approach, this study followed a qualitative phenomenological research design. Qualitative data was collected from individual semi-structured interviews with specific VC tutors; tutorial observations based on tutorials offered in the VC environment; and focus group interviews with students who attended tutorials through VC technology. Informed by the Community of inquiry (CoI) theory, the study answered the following main research question: “What are the experiences of tutors in applying instructional methodologies during VC tutorials?” The findings indicate lack of skills and reluctance in applying various active facilitation methods by VC tutors, insufficient technology training intervention by the ODL institution under study, technical challenges of VC technology in teaching and learning, and lack of monitoring systems during VC discussions. The findings further featured various factors that contribute to tutors’ ability in promoting interactivity during VC tutorials. In conclusion, this study clearly indicates that instructional methodologies used in VC tutorials cannot contribute to a meaningful teaching and learning, and thus make interactivity absent throughout VC sessions. Based on these findings, and suggestions for further research, the study therefore recommends acceleration in tutor training on exploitation and integration of VC technology with various suitable teaching methodologies. / Curriculum and Instructional Studies / M. Ed. (Didactics)

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