RAPID SEQUENCE of audioclips on a Mac

[J. Scott Saults]

I appreciate hearing from Mike Brown and Geoff Canyon regarding audio 
formats for playing in Revolution. I can confirm that 16-bit aiff 
plays fine at several sampling rates, but 16-bit wave does not, at 
least on a Mac. I'd gotten into a habit of using WAVE only under 
Windows 98 simply because that format is required by externals 
commands (the MCPsych DLLs) that I have to use to play sequences of 
sounds in memory research software I've developed for PCs. 
Unfortunately, the these DLLs are for Windows only. I 'd like to find 
a solution for the Mac OS, or I may have to (reluctantly) either 
abandon the Mac OS, or Revolution / Metacard, in my research. Let me 
explain my difficulty accomplishing a seeming simple task in 
Revolution.

For more than 12 years I've used HyperCard and SuperCard to present 
sequences of sounds, usually recorded speech but occasionally  tones, 
to be used as stimuli in STM memory research. Arbitrary sequences of 
up to 20 sound resources can be played by simply issuing a series of 
'play' commands. While the first sound begins playing, the remaining 
sounds are quickly loaded and cued to play in order, one immediately 
after the other. This provides a reasonably clean, reliable and 
precise sequence of sounds in which the onset-to-onset times, 
determined by the duration of the digitized samples, can be 
controlled within a few milliseconds. I can accomplish the same basic 
task in Revolution on the PC only by using the external commands of 
the MCPsych. DLLs, as far as I know. How can I do this in Revolution 
on a Mac, with or (preferably) without external commands?

Simply put, this is my specific QUESTION:

In Revolutionn on a Mac, with or without help from external commands, 
how can I play an arbitrary list of several different, brief (<250 
ms) sounds so they are presented as a rapid (at least 4/second), 
regular SEQUENCE.

In Revolutions on the my Mac, at least, the results of a simple 
series of 'play' and 'wait' commands, like the following, are FAR too 
slow and erratic. (Of course, without the waits, the successive play 
commands simply interrupt each other, because Revolution cannot, to 
my knowledge, cue the sounds.)

## soundList is just a list of names of the audioclips
put 250 into onsetToOnset
Repeat with i = 1 to 5
	put milliseconds() into onsetTime
	play line i of soundList
	wait until milliseconds() - onsetTime > onsetToOnset
end repeat

Neither getting the milliseconds after the 'play' command, nor using 
'wait until the sound is "done"' works any better in my tests.

Does anyone have any suggestions for how to accomplish this better?

Many thanks in advance for any new ideas.

	Desperately seeking answers,
		Scott Saults



J. Scott Saults, Ph.D.
Research Associate
	email: SaultsJ at missouri.edu
Department of Psychology
	210 McAlester Hall