Keyboard response, a second too much?

Flippy

Hello guys,
I wrote a script which has to do the following things:
1. play a sound and wait for 3.5 seconds
2. after these 3.5 seconds, wait for the operator to press a key with a time window of 4 seconds. Instead of proceeding after the keypress, wait the whole 4 seconds.
3. repeat step 1 and 2 for a certain amount of times

My script for that:

def sound_play():

j=1
while j<11:
    sound = "0" + str(j) + "_Set1_einfach_3.5sec.wav"
    src = pool[sound]
    my_sampler = sampler(src, volume=1)
    my_sampler.play()
    t1=time.clock()
    #print(t1)
    j=j + 1
    self.sleep(3500)

    start_time = time.clock() * 1000
    key_response = keyboard(keylist = ['a'], timeout=4000)
    key, end_time = key_response.get_key()
    #end_time = end_time - 1000
    var.response = key
    var.response_time = end_time - start_time
    diff = 4000 - int(var.response_time)
    clock.sleep(diff)
return

the following problem appaers: when the operator presses 'a' immidiatly after the 3.5 seconds of soundplaying there is still a response_time of >1000 milliseconds. I found out that the end_time I get from get_key() is one second more than it should be but I don't know why?! Fixing it by just subtracting 1000 ms from end_time semms not right for me.

Do you guys have any idea?
Thanks a lot!

sebastiaan

Hi Flippy,

It seems that you sleep for 3500 ms because that's how long the sample is. Is that correct? If so, then it's much better to use blocking playback, which will cause my_sampler.play() to pause until the sample is done playing.You can do this with the block playback keyword:

my_sampler.block = True

Does that make sense?

Other than that, you have some oddities in your script; for example, time.clock() should probably be clock.time().

See also:

• http://osdoc.cogsci.nl/3.1/manual/python/sampler/#playback-keywords

Cheers,
Sebastiaan