Continuing SoundOut with changing Word display

[David McFarlane]

Mike,

At 2/8/2008 03:07 PM Friday, you wrote:
>I want to play a .wav file throughout the
>experiment. I don't want it to begin and end on each trial but to
>actually last for the entire block of the lexical decision task. There
>doesn't need to be any allowable response made what's played on
>the .wav file, I just want it to play in the background. Is there a
>way to do this?

I can think of two ways to do this, maybe somebody else can come up 
with something better.  The first way takes advantage of standard 
properties of the SoundOut object, and the second uses inline script.

(1)  The key here is that the duration of an object that plays a 
sound is distinct from the duration of the sound that the object 
plays, and either one can be longer than the other.  So, e.g, if you 
set the duration of a SoundOut object to 0 and set StopAfter to No, 
then the SoundOut object will start playing the sound, then the 
object will end while the sound continues playing.  Your program may 
then do something else while the sound keeps playing.

(2) In inline script you can use something like SoundOut1.Play.  This 
will simply start playing the sound and then continue your program 
while the sound plays (you will still need a SoundOut1 or whatever 
object in Unreferenced E-Objects or somewhere).  In fact, as the 
online E-Basic 1.1 help itself says in its description of the 
SoundOut.Play method, "Playback is asynchronous, (e.g. the .wav file 
begins playing and then program execution continues with the next 
object in the procedure)...  Playback is not affected by the Duration 
property of the SoundOut object", and, "SoundOut.Play differs from 
SoundOut.Run, which is not asynchronous and may or may not play the 
entire file, depending upon the values for the Duration and StopAfter 
properties" (SoundOut.Run is what happens when you have a SoundOut 
object in your E-Studio structure).


The script method is a bit cleaner, and for all I know is slightly 
more efficient with computer resources.  On the other hand, script 
obscures the structure of your experiment, and it may require objects 
sitting mysteriously in the Unreferenced E-Objects area of the 
E-Studio structure view.  Using a SoundOut object with duration 0 and 
no Stop After has the virtue that it is plainly visible in the 
structure view of your experiment.  It's up to you.

-- David McFarlane, Systems Designer
    Dept. Psychology, Michigan State University


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