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Re: cheap headphone + sound card (UNCLASSIFIED)

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

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,


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

- 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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