Classification: UNCLASSIFIED Caveats: NONE I am not familiar with this particular USB sound card, but in general USB-based devices are known for having latency problems. This is inherent to the USB bus on the PC, which in Windows natively is polled at only 100Hz... Thus data only sent in 10 ms "bins", although these days w/ USB 2.0 it can be pretty high bandwidth (data intensive) within those times. This leaves the potential for (1) latency/onset problems and (2) chopping. Now (2) seems to be fixed w/ a good buffer and drivers, which I'm sure those units have, but you still have the latency problem... ... Except, that there are some 3rd party software tools (freeware) to change the poll rate (think of it like the refresh on a monitor) for the whole USB bus, I believe it can be up to 1200 Hz or so. This might get around problem #1. I haven't tested a USB soundcard with this "fix" yet, but it did the trick on a latency problem we had once with USB input deices (e.g. keyboard). Since I also do visual-auditory integration, I appreciate the low latency concern. I say, pick one up and test it out... and report back the results! I'm very curious. It would be simple to test empirically if you have an oscilloscope and a parallel port interface card. Good luck, Dave ------------------------------- Dr. W. David Hairston Research Fellow Oak Ridge Affiliated Universities Auditory Research Team, VAP, HRED Army Research Lab Aberdeen Proving Ground, MD 21005 Office: (410) 278-5925 Fax: (410) 278-3587 -----Original Message----- From: AUDITORY - Research in Auditory Perception [mailto:AUDITORY@xxxxxxxxxxxxxxx] On Behalf Of Massimo Grassi Sent: Wednesday, December 03, 2008 8:35 AM To: AUDITORY@xxxxxxxxxxxxxxx Subject: [AUDITORY] cheap headphone + sound card Dear list members, (apologies for the 100th technical question about headphone and soundcards) - I need to buy 30 headphones for our computer room. I was looking for something cheap (say less than 30-40 euros per headphone) but (hopefully) not as bad. Any suggestion is welcome. (I remember a recent post with a similar question. I looked for it in the archive but I didn't found it.) - I'm about to buy a sound card for the psychoacoustics/crossmodal perception lab. I was targeting a USB M-AUDIO (i.e., Fast Track pro or Fast track ultra). The idea of the USB was that we may move easily the sound card if we need it. Does anyone have experience (good or bad) with these soundcards? Is there any reason why I should avoid USB cards (or these two in particular)? Is any of you aware of temporal delays of USB sound cards when they are used together in synchro with visual stimuli (e.g., stimuli created with the psychtoolbox for example). Any suggestion is more than appreciated, m Classification: UNCLASSIFIED Caveats: NONE
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