Always use a global pointer for the sound "handle", and where your code wants to play have this
Code:
//global handles
SOUND* footsteps1 = "footsteps.wav";
var Snd_Channel_1;

function Inside_Any_Function_or_Action()
{
   ...
   //only START playing if already finished
   if(snd_playing(Snd_Channel_1)==0)   Snd_Channel_1 = snd_play(footsteps1, 100, 0);
   ...
}
PS. you can have up to 32 Channels according to the manual.

"There is no fate but what WE make." - CEO Cyberdyne Systems Corp.
A8.30.5 Commercial