Re: advice on equipment (headphones, microphones, sound cards)

[Pawel Kusmierek <pawel.kusmierek@xxxxxxxxx>]

Dear Maria,

soundblaster cards are known for various departures of real
specifications from published specifications, for undocumented
features, and for features which are supposed to make the sound more
attractive for a gamer, but they damage accuracy. I don't know about
the X-Fi line, but Audigy 2NX (and possibly all Audigy cards) is
advertised as having 24-bit converters. They are probably 24-bit, but
the data always go through a signal processor which is 16-bit, and the
8 least significant bits are lost.  Any CMSS or whatever is the
current name for their spatial enhancement systems must be turned off
if any accuracy is to be expected. And CMSS is on by default.
SoundBlaster cards are also known for supporting only few sampling
frequencies, i.e., 48 kHz and sometimes 96 kHz. Anything else will be
resampled on the fly by the card, and the quality of the resampling
might be poor - though this problem is especially annoying with some
onboard cards.  Of other "interesting" features, my experience was
that SB Live! 1024 had an undocumented compressor built in into top ~3
dB of the recording range. There was no way to turn it off.

The bottom line is - I would stay away from SB cards for serious
applications. I had good experiences with M-Audio cards (though I
never tried the Transit).  Edirol, ESI and E-mu are other respectable
companies which make external soundcards. The Echo and Digigram PCMCIA
cards should be very good, too.

HD280 are a decent choice if you want closed headphones. I hope that
you are aware that they won't work in an fMRI scanner, it would be
even very dangerous to bring them into a scanner!

Hope this helps,

Pawel



On 29/08/2007, Chang, Maria <Maria.Chang@xxxxxxxxxxxxxxxxxxxxx> wrote:
> Hello,
>
> I am purchasing equipment for auditory fMRI experiments run off of a laptop.  I am looking for a sound card (PC card, usb, or ExressCard), headphones and a microphone.
>
> The recording capabilites of the sound card and microphone don't need to be top of the line, they just need to be good enough for us to record quality auditory stimuli (i.e. we will not be collecting speech data from subjects).  Although, if a sound card with outstanding recording capabilities is only slightly more expensive, then I would be willing to invest in it in case we decide to collect speech data in the future (same goes for the microphones).
>
> So far I've found the following options:
>
> Headphones - Sennheiser HD280 PRO
> Microphones - Shure SM-93, Audio Technica AT803B
> Sound Cards - Echo Indigo, M-Audio Transit, Digigram VxPocket, SoundBlaster Audigy 2Zs, SoundBlaster X-Fi Extreme
>
> Any recommendations (on or off this list) or objections?  Any advice is greatly appreciated!
>
> Thanks!!
>
> -maria
>


-- 
Pawel Kusmierek PhD
Department of Physiology and Biophysics
Georgetown University Medical Center
The Research Building WP23
3970 Reservoir Road NW
Washington, DC 20007
phone: +1 202 687-8851 or 8028