Re: tapping hardware & software (Bob Masta )


Subject: Re: tapping hardware & software
From:    Bob Masta  <audio@xxxxxxxx>
Date:    Thu, 24 Mar 2011 09:35:06 -0500
List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>

Daniele: I concur with Christian's idea of using a cheap microphone to record the tapping, assuming the subjects listen with headphones to avoid crosstalk. However, to get accurate timing measurements you will need to record the mic and the stimulus on separate (L and R) sound card channels. (Sound card L and R inputs are always synchronous with each other, and L and R outputs are synchronous with each other, but the outputs are not synchronous with the inputs, so you need to record the output as an input.) Since sound card Mic inputs are always mono, you will need to use Line In, with an external preamp to boost the mic. (You might be able to get away without the preamp, since this task doesn't require high fidelity and the mic can be placed very close to the subject... the subject could even tap directly on the mic.) Then all you need is to route the stimulus to (say) the left Line In, and the mic output to the right. This will require some "trick" cabling, either by cannibalizing cheap sound card cables or buying "splitter" cables. I think my Daqarta software for Windows can do the whole job. It can do all sorts of pulse and tone burst generation (and just about anything else you can think of), and it can play sound recordings as stimuli as well. Let me know the details of what you want, and I can help you create a stimulus setup. Daqarta can then record the combined signal to a file. As far as analysis goes, I have no experience with Christian's suggestion of Octave, but it sounds like it would do the job. Daqarta can do some of this intrinsically: You can scroll through the file manually, of course, and measure the relative times with on-screen cursors. But a better way is to use the Trigger controls in Single mode, such that the file scrolls automatically to the next tap or stimulus event (which would be under one cursor), and you'd then place the other cursor on the other event (stimulus or tap) and read the timing difference directly on the Delta cursor readout. Then you hit the Trigger button to advance to the next event. Daqarta has a macro scripting facility, so in principle much or all of this could be automated. But some of the features needed to do this particular task won't be available for a couple of months yet. A Daqarta Professional license is US$99, but you can try everything free for 30 sessions or 30 days. After that, you can still analyze files, but you can't record from the inputs. So if you can collect all your data in one month, you can do everything for free! Best regards, Bob Masta ======================= On 24 Mar 2011 at 9:32, daniele schon wrote: > Dear all, > I am trying to think to a simple and cheap solution to record children > in a tapping task (eg along with a metronome or a piece of music). > I have up to now found several solutions commonly used, but none of them > is cheap. For instance, using a software such as Presentation to send > the auditory stimulus and record with the space bar (requires > Presentation/E-Prime license), or using Cakewalk and a tapping pad > (requires Cakewalk license and a tapping pad). > So I would be glad if you could share your advice on the "optimal" > solution, optimizing the real cost (in euros), the precision (in > milliseconds) and the other cost (the hours I'll spend analyzing data, > for instance recording the tapping on a microphone ...). > > my warmest regards > daniele > > -- > Daniele Schön > Equipe Langage, Musique et Motricité > Institut de Neurosciences Cognitives de la Méditerranée > C.N.R.S, 31, Chemin Joseph-Aiguier > 13402 Marseille Cedex 20, France > Tel: 0033 (0) 4 91 16 41 30 > Fax: 0033 (0) 4 91 16 44 98 > > http://www.incm.cnrs-mrs.fr/pperso/danieleschon.php > > I CHOOSE PEACE Bob Masta D A Q A R T A Data AcQuisition And Real-Time Analysis www.daqarta.com Scope, Spectrum, Spectrogram, Signal Generator Science with your sound card!


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