The problem is if you set something to play while you are touching the screen it will be triggered over and over as long as you touch the screen until you crash the sound card.
You need a more specific trigger and a way to stop that sound after it has played.
You could use a Y and X variable on the touch control for that trigger and I would check the acceleration of the drag. Keep the sounds short and add an auto stop so they don't overlap.
On Y > 100: Play sound
and X > 100
and Touchacceleration >50
On Y < 100: Stop all sound
Or X < 100
and Touchacceleration <50
Every 3 seconds: Stop all sound
Something like that.
You could also use blank sprites as trigger points on your screen that when the user slides across changes the sound being played.
Here is a CAPX for a continuous drag to change sounds using sprites:
https://www.dropbox.com/s/dr7susdzqyatyg4/Sound%20Touch%20Control.capx?dl=0