On Wed, Jul 21, 2010 at 10:07:10PM +0200, JohnLM wrote: > What's the thing about far and near fields?
The rule pressure = 1 / distance is true only for theoretical point sources, and for real sources if the distance is much larger than the size of the zource. In the other case you are in the 'near field' where things can get quite complex. For some sounds you are almost always in the 'near' field e.g. a highway with many moving cars on it, the seashore, etc. These are essentially large line sources with many independent sound generators which blurr into a single sound, and in that case you'd get different relations, e.g. pressure = 1 / sqrt(distance). > On Wed, Jul 21, 2010 at 2:01 PM,<f...@kokkinizita.net> wrote: > >An audio signal represents pressure variation as a function of > >time. Multiplying it by two will give 2 times the pressure, > >and 4 times the power. The subjective result is another matter. > > > Ummm... is it sound pressure or sound pressure level? Or it doesn't > matter? (are they equivalent?) The term 'sound pressure level' (SPL) usually refers to sound pressure measured in a standardized way. What you try to do is called spatialization. It involves modelling the directivity and motion of the sources and their interaction with the space they are in, and it can get arbitrarily complex. Software to do this in specialised cases (e.g. electronic music) exists. More general solutions and in particular practical systems (allowing complex and dynamic scenes) are still a research topic, e.g. at Barcelone Media. Ciao, -- FA There are three of them, and Alleline. _______________________________________________ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
