Audio networking is a rapidly increasing field which introduces new exiting possibilities for the professional audio industry. When well established, it will drastically change the way live sound systems will be designed, built and used. Today's networks have enough bandwidth that enables them to transfer hundreds of high quality audio channels, replacing analogue cables and intricate installations of conventional analogue audio systems. Currently there are many systems in the market that distribute audio over networks for live music and studio applications, but this technology is not yet widespread. The reasons that audio networks are not as popular as it was expected are mainly the lack of interoperability between different vendors and still, the need of a wired network infrastructure. Therefore, the development of a wireless digital audio networking system based on the existing widespread wireless technology is a major research challenge. However, the ΙΕΕΕ 802.11 standard, which is the primary wireless networking technology today, appears to be unable to handle this type of application despite the large bandwidth available. Apart from the well-known drawbacks of interference and security, encountered in all wireless data transmission systems, the way that ΙΕΕΕ 802.11 arbitrates the wireless channel access causes significantly high collision rate, low throughput and long overall delay. The aim of this research was to identify the causes that impede this technology to support real time wireless audio networks and to propose possible solutions. Initially the standard was tested thoroughly using a data traffic model which emulates a multi-channel real time audio environment. Broadcasting was found to be the optimal communication method, in order to satisfy the intolerance of live audio, when it comes to delay. The results were analysed and the drawback was identified in the hereditary weakness of the IEEE 802.11 standard to manage broadcasting, from multiple sources in the same network. To resolve this, a series of modifications was proposed for the Medium Access Control algorithm of the standard. First, the extended use of the "CTS-to-Self" control message was introduced in order to act as a protection mechanism in broadcasting, similar to the RTC/CTS protection mechanism, already used in unicast transmission. Then, an alternative "random backoff" method was proposed taking into account the characteristics of live audio wireless networks. For this method a novel "Exclusive Backoff Number Allocation" (EBNA) algorithm was designed aiming to minimize collisions. The results showed that significant improvement in throughput can be achieved using the above modifications but further improvement was needed, when it comes to delay, in order to reach the internationally accepted standards for real time audio delivery. Thus, a traffic adaptive version of the EBNA algorithm was designed. This algorithm monitors the traffic in the network, calculates the probability of collision and accordingly switches between classic IEEE 802.11 MAC and EBNA which is applied only between active stations, rather than to all stations in the network. All amendments were designed to operate as an alternative mode of the existing technology rather as an independent proprietary system. For this reason interoperability with classic IEEE 802.11 was also tested and analysed at the last part of this research. The results showed that the IEEE 802.11 standard, suitably modified, is able to support multiple broadcasting transmission and therefore it can be the platform upon which, the future wireless audio networks will be developed.

Dissertation (PhD)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: The main purpose of the study is to develop a model and to establish certain principles for writing a script treatment (personal pictures) of a book of the Bible. Personal pictures can be identified as the most important component of the production (filmic creation) and marketing (promulgation) processes of a fully dramatised audio-visual representation of a biblical book. The study deals primarily with personal pictures. Changes in the communication and perception of biblical content are investigated. The study focuses mainly on the dissemination of such content through audio-visual Bible products (end products). The study contends that audio-visual Bible communications for children and adults should have an educational foundation. The other main dimension of all audio-visual Bible is the entertainment it provides to viewers (patrons). The educational and entertainment facets of end products are described here as edutainment. It is important for end products to have edutainment value as perceived by socio-economically diverse peoples, of both Christian and non-Christian (non-religious) persuasions. Aspects which can contribute to the edutainment value of fully dramatised audio-visual Bible products are expounded. An audio-visual model, which defines the basis for the filmic creation and promulgation of an end product, is explained and its elements described. The determinants of the filmic creation and promulgation processes, some of which have a greater educational impact and some which have a greater entertainment impact, are explicated. An important factor is to involve patrons in the filmic creation and promulgation processes, and to help them to feel part of these processes. Writing the personal pictures of a Bible book is investigated. A personal pictures model is put forward to explain how the personal pictures can be written. A variety of guidelines to help the writer (owner) write the personal pictures of a book are presented. These guidelines deal with aspects such as writing the narrative, selecting the context of the storytelling, gathering and using background information, using enhancement factors, and implementing requirements of the users. The personal pictures already written of two Bible books are assessed. An explanation is given of why the books of Ruth and Hebrews, one from the Old and one from the New Testament, are chosen for such assessment. These personal pictures are found to be deficient and new personal pictures are written for both books, using the model and guidelines given. An empirical survey is undertaken of the personal pictures of one of the two books assessed, namely Ruth. The analysis of the empirical research finds that the respondents are able to visualise a film of Ruth with edutainment value after reading the personal pictures. The results of the survey point to the importance of both the educational and entertainment aspects in end products. Some further valuable deductions can be made from the study: Audio-visual Bible products are beneficial to convey biblical content to patrons. A model and guidelines are presented for writing good quality personal pictures. Patrons can profitably be engaged in the filmic creation and promulgation processes of fully dramatised audio-visual Bible products. A few constraints have been encountered which have a limiting effect on the study. The study highlights a number of important areas which can be further researched. / AFRIKAANSE OPSOMMING: Die hoofdoel van die studie is om sekere riglyne neer te Ie vir die skryf van 'n draaiboeksinopsis of visuele voorstelling ("personal pictures") van 'n Bybelboek. "Personal pictures" van 'n Bybelboek is waarskynlik die belangrikste komponent van die vervaardigings- en verspreidingsprosesse van 'n volledig-gedrarnatiseerde oudio-visuele weergawe van so 'n boek. Die studie handel hoofsaaklik oor "personal pictures". Veranderinge in die kommunikasie en in die begrip van die inhoud van die Bybel word ondersoek. Die studie fokus hoofsaaklik op die uitdra van die inhoud van Bybelboeke deur middel van oudio-visuele Bybelprodukte. Die studie toon aan dat oudio-visuele Bybelkommunikasie vir kinders en volwassenes 'n opvoedkundige grondslag het of behoort te he. Die ander belangrike grondslag van 'n oudiovisuele Bybel is die vermaaklikheidsaspek. Die opvoedkundige en vermaaklikheidsfasette van oudio-visuele Bybelprodukte word hierin beskryf as opvoedkundige vermaak ("edutainment"). Dit is belangrik dat oudio-visuele Bybelprodukte "edutainment'' verskaf aan uiteenlopende sosio- . ekonomiese groepe van sowel Christel ike as nie-Christelike oortuiging. Sekere aspekte word verduidelik wat die waarde van "edutainment" in gedramatiseerde oudiovisuele Bybelprodukte kan verhoog. 'n Oudio-visuele model, wat die grondbeginsels vir die vervaardiging en verspreiding van so 'n Bybelproduk uiteensit, word verskaf en die onderskeie beginsels word gedefinieer. Die bepalende faktore in die vervaardigings- en verspreidingsprosesse, waarvan sornmige 'n groter opvoedkundige en ander 'n groter vermaaklikheidsimpak het, word uitgewys. 'n Belangrike faktor is dat verbruikers by die vervaardigings- en verspreidingsprosesse betrek word, en op 'n wyse wat hulle dee I van hierdie prosesse laat voel. Hoe om "personal pictures" van 'n Bybelboek te skryf, word ondersoek. 'n "Personal pictures"- model word aangebied, asook 'n verskeidenheid riglyne vir die skryfvan die "personal pictures" van 'n boek. Hierdie riglyne omvat aspekte soos die storielyn, die keuse van die konteks waarin die storie afspeel, die inwin en gebruik van agtergrondinligting, die gebruik van effekte wat die storie bevorder, en die toepassing van spesifieke vereistes van die vervaardigingspersoneel. Die "personal pictures" wat reeds van twee Bybelboeke bestaan, word beoordeel. 'n Verduideliking word gegee waarom Rut en Hebreers, boeke uit onderskeidelik die Ou en die Nuwe Testament, vir so 'n evaluering gekies is. Hierdie "personal pictures" word as ontoereikend bevind, en nuwe "personal pictures" word vir beide boeke geskryf deur van die genoemde model en riglyne gebruik te maak. 'n Empiriese ondersoek word gedoen om die "personal pictures" van een van die twee boeke, naamlik Rut, te evalueer. In die ontleding van die empiriese ondersoek word bevind dat respondente in staat is om 'n film van Rut met "edutainment"-waarde te visualiseer, nadat hulle die "personal pictures" gelees het. Die resultate van die ondersoek wys op die belangrikheid van die opvoedkundige sowel as die vermaaklikheidsaspekte van oudio-visuele Bybelprodukte. Die volgende verdere waardevolle afleidings word uit die studie gemaak: Die inhoud van Bybelboeke kan met vrug deur middel van oudio-visuele Bybelprodukte oorgedra word. Goeie kwaliteit "personal pictures" kan geskryf word deur gebruik te maak van die voorgestelde model en riglyne. Dit kan voordelig wees om verbruikers by die vervaardigings- en verspreidingsprosesse van gedramatiseerde oudio-visuele produkte van die Bybel te betrek. Die faktore wat 'n beperkende uitwerking op die studie gehad het, word aangetoon. Die studie lig 'n aantal belangrike areas uit vir verdere navorsing.

The purpose of this problem was to select audio-visual materials that would enhance the teaching of music in the primary grades. Since audio-visual equipment and materials have gained a place of prominence in the modern education program, the teachers, administrators, and even the architects need to be cognizant of their possibilities and applications. Audio-visual aids should be investigated to disclose ways of improving their utilization in the learning process through the stimulation of the following human senses: sight, hearing, and touch. The results of many experimental research studies in the field of audio-visual education have proved that the application of audio-visual devices in the classroom greatly improves both understanding and retention as compared to conventional teaching methods. It is hoped that the identification, enumeration, and suggestions for utilization of audio-visual aids presented in this study will motivate the reader to give further attention to audio-visual materials as applied to his specific situation, with the awareness of their unlimited possibilities in increasing understandings through sensory experiences.

[pt] Através desta dissertação, foi possível avaliar e definir recursos ergonômicos de áudio com análises de sites corporativos da Internet, para posteriormente verificar a aceitação destes recursos pelo usuário. Inicialmente, foram apresentados conceitos relativos à utilização de áudio em sites da Internet para melhor compreender os processos relacionados. Depois, foram realizados procedimentos para delimitar amostras e avaliar os efeitos dos recursos ergonômicos de áudio na experiência do usuário. Verificou- se que a adequação dos recursos ergonômicos de áudio é um fator primordial em sites que utilizam áudio na Internet e a falta de testes com o usuário no processo de desenvolvimento de sites compromete o uso do áudio. Sem conhecer o modelo- mental do usuário, não há como definir os quesitos mais importantes relacionados ao áudio. Percebeu-se também a importância de organizar resultados para auxiliar no desenvolvimento de projetos que envolvam aspectos ergonômicos ou de usabilidade. Assim, conclusões sobre os principais recursos ergonômicos de áudio foram apresentadas em seções distintas para facilitar sua aplicação. / [en] This thesis evaluated and defined audio ergonomic resources through the analysis of corporative sites from Internet, verifying the acceptance of these resources with the user. Initially, related concepts to audio application in sites of the Internet were presented to better understanding envolved processes. Later, procedures had been carried through to establish scopes and audio ergonomic resourses effects in the user experience were evaluated. It was noted that the adequacy of audio ergonomic resources is a primordial factor in sites that use audio in the Internet and the lack of tests with the user in the process of development of sites compromises the audio applications. Without knowing the mental-model of the user, it is impossible to define the most important itens related to audio. The importance of organizing research data results to assist in the development of projects that involve ergonomic or usability aspects was also noted. Thus, conclusions on the main audio ergonomic resources had been presented in distinct sections to facilitate its applications.

Nos últimos anos os avanços em áudio multicanal e sistemas envolventes despertaram um grande interesse pelas técnicas para a auralização de campos sonoros espaciais, capazes de recriar ambientações acústicas com grande realismo, envolvendo o ouvinte completamente. Um estudo sobre as tecnologias e soluções para áudio espacial mostrou que a construção de auralizadores envolve quatro blocos funcionais fundamentais. Mas, embora existam muitas técnicas e ferramentas disponíveis, não há uma arquitetura integradora para produção de áudio espacial que permita ao desenvolvedor selecionar as técnicas que deseja e montar uma solução com um grau de refinamento arbitrário que atenda a seus requisitos. Apresenta-se uma arquitetura modular aberta em quatro camadas para produção de áudio espacial em ambientes audiovisuais imersivos. Como estudo de caso, aborda-se a implementação de um auralizador Ambisonics para a CAVERNA Digital. Verifica-se que a auralização pode fornecer a correta perspectiva acústica do ambiente virtual necessária para uma percepção mais realista do espaço, e que a abordagem aberta para se implementar sistemas de áudio 2D/3D apresenta vantagens. Os resultados da implementação são apresentados e discutidos. Como conclusões, identificam-se desafios na implementação e os trabalhos futuros. / Recent advances in multichannel audio and surround systems have contributed to an increasing interest for spatial sound field auralization, capable of delivering acoustic ambience with great realism, and surrounding listener completely. A study on technologies and solutions for spatial sound has shown that building auralizators involve four major functional blocks, but, although there are many techniques and tools available, there is not an integration architecture for spatial audio production which permits developers to select their favorite techniques, and build a solution with an arbitrary refinement level, as wished. It is presented a four level modular open architecture for spatial audio production in immersive audiovisual environments. As a case study, an Ambisonics auralizator is implemented for the CAVERNA Digital CAVE. It is verified that auralization can deliver the correct acoustical perspective for the virtual environment necessary for a more realistic perception of space, and that an open approach presents advantages in 2D/3D audio systems design. Implementation results are presented and discussed. As conclusions, challenges and future works are presented.

The mixing desk metaphor found in Digital Audio Workstations (DAW) is built upon a specialised and technical knowledge of signal flow and audio engineering. However, since their inception the DAW has gained a far wider and less technically specialised user-base. Furthermore, the limited screen space of laptop and tablet computers, combined with potentially limitless tracks in current DAWs has resulted in the need for complex interface navigation during mixing which may inhibit a fluid and intuitive approach to mixing. The research outlined in this thesis explores novel designs for Graphical User Interfaces (GUIs) for mixing, which acknowledge the changing role of the user, the limited space of tablet and mobile computers screens and the limitations of human perception during cross modal activities (aural and visual). The author designs and conducts several experiments using non-expert participants drawn from several music technology courses, to assess and quantify the extent to which current DAW designs might influence mixing workflow, aiming our research especially at beginner and non-expert users. The results of our studies suggest that GUIs which load visual working memory, or force the user to mentally integrate visual information across the interface, can reduce the ability to hear subtle simultaneous changes to the audio. We use the analysis of these experiments to propose novel GUI designs that are better suited to human cross-modal perceptual limitations and which take into account the specific challenges and opportunities afforded by screen-based audio mixers. By so doing, we aim to support the user in achieving a more fluid and focused interaction while mixing, where the visual feedback supports and enhances the primary goal of attending to and modifying the audio content of the mix. In turn, it is hoped this will facilitate the artistic and creative approaches required by music computer users.

Nos últimos anos os avanços em áudio multicanal e sistemas envolventes despertaram um grande interesse pelas técnicas para a auralização de campos sonoros espaciais, capazes de recriar ambientações acústicas com grande realismo, envolvendo o ouvinte completamente. Um estudo sobre as tecnologias e soluções para áudio espacial mostrou que a construção de auralizadores envolve quatro blocos funcionais fundamentais. Mas, embora existam muitas técnicas e ferramentas disponíveis, não há uma arquitetura integradora para produção de áudio espacial que permita ao desenvolvedor selecionar as técnicas que deseja e montar uma solução com um grau de refinamento arbitrário que atenda a seus requisitos. Apresenta-se uma arquitetura modular aberta em quatro camadas para produção de áudio espacial em ambientes audiovisuais imersivos. Como estudo de caso, aborda-se a implementação de um auralizador Ambisonics para a CAVERNA Digital. Verifica-se que a auralização pode fornecer a correta perspectiva acústica do ambiente virtual necessária para uma percepção mais realista do espaço, e que a abordagem aberta para se implementar sistemas de áudio 2D/3D apresenta vantagens. Os resultados da implementação são apresentados e discutidos. Como conclusões, identificam-se desafios na implementação e os trabalhos futuros. / Recent advances in multichannel audio and surround systems have contributed to an increasing interest for spatial sound field auralization, capable of delivering acoustic ambience with great realism, and surrounding listener completely. A study on technologies and solutions for spatial sound has shown that building auralizators involve four major functional blocks, but, although there are many techniques and tools available, there is not an integration architecture for spatial audio production which permits developers to select their favorite techniques, and build a solution with an arbitrary refinement level, as wished. It is presented a four level modular open architecture for spatial audio production in immersive audiovisual environments. As a case study, an Ambisonics auralizator is implemented for the CAVERNA Digital CAVE. It is verified that auralization can deliver the correct acoustical perspective for the virtual environment necessary for a more realistic perception of space, and that an open approach presents advantages in 2D/3D audio systems design. Implementation results are presented and discussed. As conclusions, challenges and future works are presented.

La perception des robots joue un rôle crucial dans l’interaction homme-robot (HRI). Le système de perception fournit les informations au robot sur l’environnement, ce qui permet au robot de réagir en consequence. Dans un scénario de conversation, un groupe de personnes peut discuter devant le robot et se déplacer librement. Dans de telles situations, les robots sont censés comprendre où sont les gens, ceux qui parlent et de quoi ils parlent. Cette thèse se concentre sur les deux premières questions, à savoir le suivi et la diarisation des locuteurs. Nous utilisons différentes modalités du système de perception du robot pour remplir cet objectif. Comme pour l’humain, l’ouie et la vue sont essentielles pour un robot dans un scénario de conversation. Les progrès de la vision par ordinateur et du traitement audio de la dernière décennie ont révolutionné les capacités de perception des robots. Dans cette thèse, nous développons les contributions suivantes : nous développons d’abord un cadre variationnel bayésien pour suivre plusieurs objets. Le cadre bayésien variationnel fournit des solutions explicites, rendant le processus de suivi très efficace. Cette approche est d’abord appliqué au suivi visuel de plusieurs personnes. Les processus de créations et de destructions sont en adéquation avec le modèle probabiliste proposé pour traiter un nombre variable de personnes. De plus, nous exploitons la complémentarité de la vision et des informations du moteur du robot : d’une part, le mouvement actif du robot peut être intégré au système de suivi visuel pour le stabiliser ; d’autre part, les informations visuelles peuvent être utilisées pour effectuer l’asservissement du moteur. Par la suite, les informations audio et visuelles sont combinées dans le modèle variationnel, pour lisser les trajectoires et déduire le statut acoustique d’une personne : parlant ou silencieux. Pour expérimenter un scenario où l’information visuelle est absente, nous essayons le modèle pour la localisation et le suivi des locuteurs basé sur l’information acoustique uniquement. Les techniques de déréverbération sont d’abord appliquées, dont le résultat est fourni au système de suivi. Enfin, une variante du modèle de suivi des locuteurs basée sur la distribution de von-Mises est proposée, celle-ci étant plus adaptée aux données directionnelles. Toutes les méthodes proposées sont validées sur des bases de données specifiques à chaque application. / Robot perception plays a crucial role in human-robot interaction (HRI). Perception system provides the robot information of the surroundings and enables the robot to give feedbacks. In a conversational scenario, a group of people may chat in front of the robot and move freely. In such situations, robots are expected to understand where are the people, who are speaking, or what are they talking about. This thesis concentrates on answering the first two questions, namely speaker tracking and diarization. We use different modalities of the robot’s perception system to achieve the goal. Like seeing and hearing for a human-being, audio and visual information are the critical cues for a robot in a conversational scenario. The advancement of computer vision and audio processing of the last decade has revolutionized the robot perception abilities. In this thesis, we have the following contributions: we first develop a variational Bayesian framework for tracking multiple objects. The variational Bayesian framework gives closed-form tractable problem solutions, which makes the tracking process efficient. The framework is first applied to visual multiple-person tracking. Birth and death process are built jointly with the framework to deal with the varying number of the people in the scene. Furthermore, we exploit the complementarity of vision and robot motorinformation. On the one hand, the robot’s active motion can be integrated into the visual tracking system to stabilize the tracking. On the other hand, visual information can be used to perform motor servoing. Moreover, audio and visual information are then combined in the variational framework, to estimate the smooth trajectories of speaking people, and to infer the acoustic status of a person- speaking or silent. In addition, we employ the model to acoustic-only speaker localization and tracking. Online dereverberation techniques are first applied then followed by the tracking system. Finally, a variant of the acoustic speaker tracking model based on von-Mises distribution is proposed, which is specifically adapted to directional data. All the proposed methods are validated on datasets according to applications.

This project provides an audio notification about nearby tourism place to visit (named sight in this thesis), a chapter based Audio Books related to the current sight and involving Digital Library to provide text for the Audio Books for the Tourist Information Provider on a mobile device (TIP). The current system plays a background sound for the sight only when the system displays the specific information for that sight after user selects it. This has been improved to provide a notification by which to receive audios from the recommendation service, and then keep sending audio data to clients on real time. So users can know the sight nearby before they look at their screen. The limitation of current Audio Books is that it only provides Audio Books when the books start from the current sight. This problem is solved by providing a list of books that has any chapter related to that sight, and users can add them into a now-playing list. The Travel Planning Service has been involved to place the Audio Books chapters into the now-playing list based on the order of the visiting sight in their plan. The TIP/Greenstone Service, which can load particular text from Greenstone Digital Library into TIP, has been involved in this project to provide related chapter-based text for those Audio Books. The implemented prototype has been evaluated on effeteness and performance based on the purpose of this project. The result has been discussed to prove it has effectively solved the problem described above. Finally, the result of the experiment on distinguishing audio, and technology for implementation and audio transfers, has been left for future study.

Thesis (M.Ed.)--University of Hong Kong, 1980. / Includes bibliographical references. Also available in print.