Hi!
I think that it's not a problem with the function. It is just that if the keys remain pressed, it will cause the sound to be played again and again until you release the keys. There are many solutions but one example is to wait for the release of a key to play the sound (or play the sound on key press and wait until the release of the key).

Code:
///////////////////////////////
#include <acknex.h>
#include <default.c>
#include <mtlFX.c>
///////////////////////////////

#define PRAGMA_PATH "C:\\Program Files\\GStudio7\\templates\\sounds";

SOUND* Sound1 = "explo.wav";
SOUND* Sound2 = "explosin.wav";
SOUND* Sound3 = "explosion.wav";

// do some silly movements ...
action AnimateFish()
{
	var degree = 0;
	var movePercent = 0;
	
	while (1)
	{
		degree+=time_step*5;
		movePercent += time_step*30;
		me.x = 100*sin(degree);
		me.y = 100*cos(degree);
		me.pan = -degree;
		ent_animate(me,"",movePercent,ANM_CYCLE);
		wait(1);
	}
}

function Sound()
{
	while(1)
	{
		// Play after a key was released
		if (key_1)
		{
			while (key_1) {wait(1);}
			snd_play(Sound1,50,0);
		}
		// Play on key press and wait until the key is released
		if (key_2)
		{
			snd_play(Sound2,50,0);
			while (key_2) {wait(1);}
		}
		if (key_3)
		{
			snd_play(Sound3,50,0);
		}
		wait(1);
	}
}


function main()
{
	//video_screen = 1;	 // full screen
	preload_mode = 3; // preload entities
	level_load(NULL);
	camera.x = -300;
	camera.z = 100;
	camera.tilt = -20;
	ent_create("fisch1.mdl", vector(0,0,0), AnimateFish);
	Sound();
}


Best regards.

PhysX 3 Plugin Box2D Plugin