"ETS" <emale80919@yahoo.com> wrote in message news:10r1j965n5ruh3c@corp.supernews.com...> Plum wrote: > > Hi, I'm working on a semester project on sound source localization, > > where my aim is to determine the position of the source of a sound > > using two microphones and estimating the time delay of arrival. But, > > how do I process the signals from the two microphones??? > > I mean how do I send the two signals to a PC??? > > Say i add the two siganls....ow do i separate them then? > > > You record them as wav files if you like. Matlab will read them in. > look up "wavread" command. If it's stereo, it will read in a 2D signal > array so you process the 2 channels from there. If it's mono, it > returns a 1D array. A good place to look for information on > localization is: > > http://www-engr.sjsu.edu/~duda/Duda.Research.frameset.html > > TimYou can only find the bearing with two mics and even that is not unique as the sound has the same delay (assuming you have polarity!) both in front and behind the two mixs. You can tell bearing and whether the sound is coming from the left or right of course. You will also have trouble estimating time-delay as cross correlation only works well for white noise signals and you will have reverberations too. Tom
Sound Source Localization
Started by ●December 3, 2004
Reply by ●December 4, 20042004-12-04
Reply by ●December 4, 20042004-12-04
Thanx a lot Mr.Dobson, that really helped....I have Audacity here...and will use it. Thanx a lot everyone.
Reply by ●December 7, 20042004-12-07
karthik.ravikanti@gmail.com (Plum) wrote:>Hi, I'm working on a semester project on sound source localization, >where my aim is to determine the position of the source of a sound >using two microphones and estimating the time delay of arrival. But, >how do I process the signals from the two microphones??? >I mean how do I send the two signals to a PC??? >Say i add the two siganls....ow do i separate them then?Bruel & Kjaer ( sp? Danish company ) has done a lot of work in this area. You might see if they have literature available. ( modify address for return mail ) www.numbersusa.com www.americanpatrol.com
Reply by ●December 10, 20042004-12-10
Hi everyone, I'm back. This time i need to suggest some books on "Acoustics" to purchase for our library here. Particularly related to Sound Localization. Can anyone suggest some good books?
Reply by ●December 11, 20042004-12-11
Hi everyone, I'm back. This time i need to suggest some books on "Acoustics" to purchase for our library here. Particularly related to Sound Localization. Can anyone suggest some good books?
Reply by ●December 11, 20042004-12-11
P L U M ! wrote:> Hi everyone, > I'm back. > This time i need to suggest some books on "Acoustics" to purchase for > our library here. > Particularly related to Sound Localization. > Can anyone suggest some good books? >the canonical text is probably: 3-D Sound For Virtual Reality and Multimedia Durand R Begault, AP Professionalm, ISBN 0-12-084735-3 (NB: expresses a very strong preference for headphone reporoduction, hence devotes much space to HRTFs) A good general text is: Acoustics and Psychoacoustics David M Howard, James Angus, (2nd Ed. 2001) Focal Press, ISBN 0-240-51609-5 and also from Focal Press: Spatial Audio Francis Rumsey (2001) ISBN 0-240-51623-0 I also suggest yuu post this question to the sursound mailing list. Several top engineers, acousticians and surround-sound specialists are active there. These books also include bibliographies, from which you should be able to identify more specialized/scientific texts as you need. Richard Dobson
Reply by ●December 12, 20042004-12-12
The basic math of TDOA-only (time-difference-of-arrival) localization was covered in my freshman calculus book. Since I don't have it handy, and I can't recall it from memory, I would just say look for a TDOA reference in any good book on electromagnetics. The topic is much more seriously covered in a passive radar context than in acoustics. Although, Haykin's book on array DSP is a good one, and has some very relevant stuff. Look for array processing books as they will generally have a more directly applicable mathematical context to your problem than most other approaches. The sonar DSP folks worry about this problem a lot. Also, as mentioned above, you need three or more microphones to resolve the ambiguity inherent in 2-microphone setups. I prefer 12-16 microphones for my array setups, although I have gotten by with as few as 8 in a pinch. Matlab handles the data processing well, although I use CoolEdit (now Adobe Audition) for the data acquisition. Doing it in real time requires a multithreaded approach and more than one CPU, or alternatively, an FPGA. There are lots of cheap and/or free programs to use for data acquisition. You must get one that does seamless recording to hard drive (most do this no problem), not just one that records into memory, since those have to compete with other programs that will be consuming memory as well. There really are very few of the latter about anyway. For more than 2 channels of PC audio data acquisition, you will definitely need a multichannel audio card. Event/Echo, M-Audio, MOTU, etc. all make fine cards. Look at your local Guitar Center in the Pro Audio section for some help. They have plenty of good setups for not too much money. Some of the cards have a breakout box that includes pre-amps for each channel. Someone mentioned reverberations above. Given enough microphones, the reflections can be sorted out easily, until the number of reflections exceed the degrees of freedom of the array. Start off working on an open football pitch or park (not a stadium) so as to minimise these during testing. Once you've got that sorted out, move to a more complex reverberant environment. Good luck. Cheers, Rob
Reply by ●December 25, 20042004-12-25
