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External sound devices for laptops

Stuart Rosen and othere here have been using a Dell laptop for masking experiments,
but he is not  completely happy with the sound quality (occasional glitches; a bit too much
noise in the background -- in particular a 200 Hz periodic complex), so is
looking into an external box. The SoundBlaster Extigy looks good (96 kHz
sampling rate, 24 bits) -- but does anyone have any experience with this or
similar external sound boxes? I guess it should plug in to a USB port to be
readily used, as does the Extigy. I'd also like to have ready access to its
workings from Windows 2000 and Matlab, perhaps through an ActiveX
controller. At about 149 dollars or pounds, this seems very good value to

Thank you all in advance --
P.S. If anyone is interested in running psychacoustic tasks through Matlab,
I am having reasonable success using an ActiveX sound card controller that
Rhodri Cusack developed to control Windows sound cards (thank you, thank you
Rhodri! And to Bob Carlyon who let me know about it).
I only manipulate the master volume control (keeping the digital signal as
close to maximum as possible) as the background noise level from the laptop
is determined by its setting -- the lower the better. The wave volume
control has no effect on this background noise. You need to measure the
behaviour of your volume control but the attenuations on my laptop were in
1.5 dB steps for small attenuations (up to 19.5 dB) and in 3 dB steps after
that to about 42.5 dB.
I also have been using a Logitech serial 3-button mouse to get responses, as
Matlab has good access to serial devices implemented explicitly. (Dontcha
just hate having to select a box on the screen, as well as pressing a
button!) A student of mine has also cannibalised one of these to make a more
typical response pad simply by soldering other buttons in parallel to the
switches in the mouse. You need to be a little careful about what you look
for on the serial port as different serial mice send different numbers of
bytes, but it is a relatively simple matter to make it work right. I
currently have this set up working during PET, with the listener flat on his
back and resting his hand on an inclined response box with two buttons.

Dr Andrew Faulkner
Principal Research Fellow
Dept Phonetics and Linguistics
UCL (University College London)
Wolfson House
4 Stephenson Way
tel 44 (0)20 7679 7408 (direct)
fax 44 (0)20 7383 0752
e-mail andyf@phon.ucl.ac.uk
WWW: http://www.phon.ucl.ac.uk/home/andyf/