>> VDP and DBAP is based on the same idea, but DBAP as presented in the ICMC >> 2009 paper >> >> http://www.trondlossius.no/system/fileattachments/30/original/icmc2009-dbap.pdf >> >> has a number of additional features. The important difference of DBAP and >> ViMiC as compared to ambisonics and VBAP is that there are no restrictions >> on the positioning of loudspeakers or listener. Loudspeakers are not >> restricted to a ring/sphere surrounding the listener, but could e.g. be laid >> out as a regular or irregular grid in the space. This is what makes it >> useful for installations in one or more spaces, such as art galleries and >> museums, where rings and spheres of speakers might be impractical and the >> audience is free and expected to move about. > > I really don't understand "...ambisonics and VBAP is that there are no > restrictions on the positioning of loudspeakers or listener.", at least as > regards to VBAP. We are currently - and have been for over two years now - > using VBAP in The Morning Line sculpture > (http://www.worldarchitecturenews.com/index.php?fuseaction=wanappln.projectview&upload_id=14039) > and the reason we used it rather than Ambisonics was because it could cope > with extremely irregular arrays of speakers. Comments?
Thanks for the link, that seems to be a very interesting project! It's difficult to figure out the loudspeaker setup in this sonic pavilion from the image, but reading the AES paper: http://www.aes.org/e-lib/browse.cfm?elib=15370 the 41 speakers seems to be subdivided into 6 "rooms". Each of these rooms seem to have the speakers pointing towards the sweet spot of the room (appendix A). Did these rooms coincide architectonically with the positions that audience were likely to be standing at in order to experience the work? As the azimuth and elevation of each speaker relative to the sweet spot of the room seems to be irregular, I think it makes a lot of sense to use VBAP rather than ambisonics. If you want a source to move all around the sculpture, how do make it move from one room to the next? Do you cross-fade from one sphere onto the next as it moves? Or was "room 7", the one used for spatialization into the structure as a whole using a subset of the speakers at the margins of the sculpture to create yet another sphere? With DBAP you wouldn't have to subdivide the array in order to enforce a "sphere surrounding sweet spot" way of thinking on to the sculpture. You could just describe the position of all of the speakers, and then freely move the sources around the sculpture. The theory of DBAP ideally assumes loudspeakers to be radiating the same way in all direction, and I personally know very few speakers that are close to doing so, so the sounding results would be influenced by the direction of the loudspeakers. This would need to be accounted for in the compositional process, but could spatially and sculpturally be used in meaningful ways, leave impressions of sound sources being directed towards or away from you depending on your and the speakers positions. DBAP was in fact first developed for an installation with a loudspeaker setup somewhat similar to the one of The Morning Line, although being 2D instead of 3D. I was working on a sound installation for Galleri KiT, the gallery space of the art academy in Trondheim, Norway. This gallery consists of a number of semi-connected rooms. I wanted to have a total of 16 loudspeakers distributed along the walls of the various rooms, and then have sound sources drifting around the space, from one room to the next. I first tried setting up a set of VBAP rooms, with a mechanism for moving from one room/VBAP system to the next as sources drifted. However I did not manage to find a way of doing so that felt smooth and convincing. Sound seemed to be glued to the walls of the rooms, sneaking from the wall of one room to the next in a way that I felt to be abrupt and unconvincing for what I was after. DBAP was developed late the night before the opening, and helped creating a much smoother drift. As speakers were positioned along the walls, the direction of the speakers was not experienced as problematic, it rather added to the feeling that the sound had now moved on to the next room. I hope this helps clarifying the difference. Another way of explaining would be the following: Imagine that you have a regular 3D matrix/grid of 4x4x4 speakers. The grid could be subdivided into 3x3x3 rooms, and ambisonic decoding for a cube of 8 speakers used for each of the rooms. You would then need to find a way of switching or crossfading from one cube to the next as the source moves about. Alternatively, using DBAP, you would deal with all 64 loudspeakers in one go. DBAP would simply feed the highest amount of gain to the speakers closest to the virtual source, and next to none to the ones that are far away, all while keeping the total intensity of all the loudspeakers at a consistent level. Best, Trond _______________________________________________ Sursound mailing list [email protected] https://mail.music.vt.edu/mailman/listinfo/sursound
