hlab@milton (05/01/91)
Hi Bob, I prepared a summary of our colloquium and I hope that comes near to what you expected. Yours Hilmar P.S.: The whether over here is awful, cold, chilly and rainy. We would need some virtual sunshine, including the perception of sun shining on our face. That's another sensory modality to adress isn't it. -----cut-here-----cut-here-----cut-here-----cut-here-----cut-here- Hi everybody, On April 8, we organized an international colloquium on virtual auditory environment and telepresencse. Our moderator asked me to summarize the event. General introduction: The idea of that colloquium was to give a general introduction into VR and to show some ideas, how the auditory part of VR could look like and what the current state of the art is. The colloquium nwas included within the german conference on acoustics (DAGA '91), and so it was organized and attended mostly by acousticians. However, VR is a very new field in germany and we were also able to attract the attention of other scientists. In the following, I will try to give a summary on the talks given. Thomas A. Furness, Human Interface Technology Laboratory, Seattle, Washington, USA : "Keynote Paper on Virtual Environment". (I leave comments on the HITL to our moderator, because he's the asscociate director there). Tom gave an excellent paper on the evolution of VR, the perceptual demands of humans for VR and possible solution to that demands. He also showed a video on the current activities of HITL and on the reaction of people experiencing VR. [The next two talks dealt with binaural technology. In the moment, it seems, that binaural technology is the most suitable tool for nearly all kinds of VR application.] Henrik Moeller, Aalborg University, Denmark: "Binaural Technology - Fundamentals". Henrik gave an introduction into the fundamentals of binaural technology, namley he talked on the spatial perception of sounds (direction of incidence and distance) an how to measure HTFs (head transfer functions) properly concerning microphone placing, ear drum impedance, radiation impedance of the ear canal etc.. He presented some interesting results on distance perception. It seems that there are groups of people, that do not perceive distance auditorily very well. Hans-Wilhelm Gierlich, Head Acoustics, Germany : "Binaural Technology - Applications". Head Acoustics is a small german company, which produces dummy heads for measurement and recording purposes including 1:10 scale heads, a binaural mixing console and a binaural sound analysis system. The title says everything. Application possibilities include sound documentation, noise assessment, sound design, room acoustic synthesis and analysis, entertainment, VR etc.. David Meares, BBC London, Great Britain : "Multi Channel Sound Systems for HDTV". David talked about different implementation possibilities of sound in HDTV (high definition TV). He gave a good impression on the "real-world" problems of recording, reproducing and standardization. [The next two talks dealt with Binaural Room Simulation, a method to create virtual auditory environment by calculating all the reflections of sound in a room and treating all that reflections binaurally.] Hilmar Lehnert and Jens Blauert, Ruhr-University Bochum, Germany :"Binaural Room Simulation - Principles". We tried to give an introduction to the method itself, the used algorithms (ray tracing and the mirror image method), the main problems (calculation time, validity of the model, data representation ...) and the chances to do anything in real-time. Jean-Paul Vian, CSTB, Grenoble, France : "Binaural Room Simulation - Practical Application & Use". Jean-Paul described the system they developed at the CSTB for room-acoustic purposes. He gave some very interesting ideas, how to create spatial late reverberation based on a statistical analysis of the early reflections. Maybe a good chance, to create a reverberation, that fits to the room (and does not sound like a reverberation machine) with reasonable effort. Masato Miyoshi & Nobuo Koizumi, NTT, Tokyo, Japan : "Conference Systems for Future Telecommunication Services". Masato talked on the current research work on teleconference systems at NTT, including adaptive noise cancelling systems. This methods can also be used to reproduce binaural signals with loudspeakers (transaural systems). Maybe the most interesting part should have been the "remarks on the Japanese Virtual-Environment & Tele- Existence Initiative". Well, the remarks were quite short and according to Masato, the main activities of the initiative uo to now were of administrative kind. No results of any research activities have been reported. After the colloquium, ther were the possibiliy to playing samples of simulations and for discussing (while having some fresh german beer). Some people played comparisons between real and simulated environments. There are still clearly audible differences, but properties like distance, spatial impression, localization, extension of the sound source etc. are reproduced quite well sometimes. Summary : Binaural Technology and especially Binaural Room Simulation seems to be good tools for the auditory part of VR. Real time implementations can be expected within the next few years. The main problems require mainly psychacoustical investigations, e.g. on human perception of auditory environment, on the problem of individual corrections, on our ability to seperate reflections, on the phase sensitivity of and so on. For anyone interested I can supply a list of the adresses of the speakers. Please mail any requests to Hilmar (lehnert@aea.e-technik.uni-bochum.de)