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In Neurobs Presentation please use *exclusive mode* to get the best audio performance. This means that no other programs
In Neurobs Presentation please use *exclusive mode* to get the best audio performance. This means that no other programs
can use the audio device while the experiment runs.
can use the audio device while the experiment runs.
[[File:SoundSettings.png|Presentation Mixer Settings]]
The maximum audio delay in Presentation on a lab computer at the faculty of social sciences is 24 ms. If better performance
The maximum audio delay in Presentation on a lab computer at the faculty of social sciences is 24 ms. If better performance
is necessary or more understanding is needed about the components of this delay, please read our page about [[audio delay]].
is necessary or more understanding is needed about the components of this delay, please read our page about [[audio delay]].
'''How to present sounds in Presentation'''
in SDL:
<pre>
sound{
wavefile{
filename = "beep.wav"; # The name of the sound file.
preload=true; # Make sure that the sound is loaded before it is actually used.
}myWave;
}mySound;
</pre>
Make sure to use '''preload = true;'''. This ensures that the sound is loaded into memory before the sound is used.
in PCL:
Prepare your stimuli during Inter Trial Interval, when there is enough time to do that. First, unload the previous sound, set the filename property to the new soundfile and load it.
<pre>
sub prepareTrial
begin
myWave.unload();
myWave.set_filename("beep.wav"); # or read the name from a trial list.
myWave.load();
end;
</pre>
During your experiment the sound is presented by:
<pre>
startOfPlaycall = clock.time();
mySound.present();
endOfPlaycall = clock.time();
</pre>
Please note that the moment when the sound can actually be heard from the speakers is later then the moment when the '''mySound.present()''' function is called. In our labs [march 2019], the delay (from '''startOfPlaycall''' until actual sound onset) is about 14 to 24 milliseconds when the Presenation mixer is used in exclusive mode. The function itself takes some (variable) time to execute. That time can, in the example above, be calculated by '''endOfPlaycall - startOfPlaycall'''. Then, some additional time is required before the sound actually is heard from the speakers. In our labs, that additional delay (from '''endOfPlaycall''' until actual sound onset) is about 5 to 8 milliseconds [March 2019]. When your experiment requires an exact knowledge about when the sound actually plays from the speakers, you need additional hardware, for instance a buttonbox with a soundkey.
More information about sound delays is found on our page about [[audio delay]].
== Troubleshooting ==
== Troubleshooting ==