How to stop sound on keydown?

I'm trying to create a mechanic where Spacebar is pressed down, a sound will play. The sound will continue to play while the spacebar is down. The sound should stop when the spacebar is not pressed. The problem I'm having is that when the spacebar is held down another instance of the audio will play over the existing one. Causing an overlapping and additional audio file being played. Help?

//Spacebar down

window.addEventListener("keydown", function(e){
this.instance = createjs.Sound.play("Long");
});

//Spacebar up

The audio file will stop if it's held down for a short period of time. If the spacebar is continuously being held, another instance of the audio starts playing.

window.addEventListener("keyup", function(e){
this.instance.stop();
});