Moving Listener in Ambisonics
Hello world,
I am working on a project using ambisonics to create a virtual soundscape.
I wonder if there is a way to move the listener on the ambimonitor, (instead of moving the sound sources around the speakers) in a space that the sound sources are already determined and fixed, like in real life.
thank you !
No, this is not possible in a "real-world" sense of how sound fields change as you move. Imagine for instance that you have an ambisonic microphone located near a door at the end of a corridor. Now, if you move the microphone to the other side of the door, out of the corridor and into the next room, you'd be likely to record sounds that simply were not there beforehand, at the same time as sounds present in the corridor no longer can be heard.
What can be done to the B-format sound field is various spatial transforms that will alter the sound field and might give you an effect that resembling what you are aiming for. The transform seen most often is rotate, tilt and tumble, that would equal moving your head while remaining in the same position. A number of other transforms are available as well, although I don't know if they have been implemented for Max. I have ported the Ambisonic Toolkit from SuperCollider to a set of plugins for the Reaper DAW. You can download and check them out from ambisonictoolkit.net. There's also a paper from ICMC/SMC this year that might provide some additional insights on them. Playing around with them in Reaper migh give you some ideas of what can be done.
Cheers,
Trond
Hello Therese,
i am working on such a project, albeit so far i'm having success only with IRCAM's Spat as it is indeed a bit difficult to translate the movements of several sound sources in a "real-life-ish" fashion and in 3D with a free solution. For Ambisonics, i didn't find yet a solution in 3D, plus i don't have access to an ambisonic setup of speakers anyway. Spat can use several spatialization algorithms, including ambisonics (which i didn't try), it's working fairly well in binaural, i think i have used the default one which must have been VBAP or DBAP. But translating coordinates for every object in the scene sort of works. So there is that !
I intend to share this project here, but it's not quite completely ready for public distribution.
A bit old (and largely outmoded, and IMO underrated) now, but COSM http://www.allosphere.ucsb.edu/cosm/ includes (still) useful objects for ambisonic encoding/decoding. It is possible to move either sound producing 'agents' or the camera/sound field (or both for that matter) through a (limited) 3D virtual world. I've used it for a couple of immersive audio projects and it works pretty well - though caveats of precision localisation with ambisonics apply and occasional zippering of 'fast' moving sounds may occur. It also still works in Max 6 though having not had to do install it in a long time I'm not certain if it will install seamlessly - or easily- in MAx 6 without some manual intervention. Its perhaps not too easy to grasp quickly as the general approach in the spatial audio (among others) examples requires the use of poly~s but with some study they will hopefully give some ideas on how you might solve your problem...
Thank you for your help ! I do the research for your advices.
I will let you know about the progress if you are interested. (I am working on the ICST_ambisonics.)
Cheers,
Therese
just have seen a new ambisoncics library posting here which looks very promising: