Make door play sound when you open and close it ?

Hai everyone. Today I need a bit of help to add more immersion to my game. I want a sound play when I open and close the door. Here's the script (not mine btw, thanks to Max A.V. https://www.youtube.com/watch?v=vfL7kQeZtic)

 // Smothly open a door
 var smooth = 2.0;
 var DoorOpenAngle = 90.0;
 private var open : boolean;
 private var enter : boolean;
 
 private var defaultRot : Vector3;
 private var openRot : Vector3;
 
 function Start(){
 defaultRot = transform.eulerAngles;
 openRot = new Vector3 (defaultRot.x, defaultRot.y + DoorOpenAngle, defaultRot.z);
 }
 
 //Main function
 function Update (){
 if(open){
 //Open door
 transform.eulerAngles = Vector3.Slerp(transform.eulerAngles, openRot, Time.deltaTime * smooth);
 }else{
 //Close door
 transform.eulerAngles = Vector3.Slerp(transform.eulerAngles, defaultRot, Time.deltaTime * smooth);
 }
 
 if(Input.GetKeyDown("e") && enter){
 open = !open;
 }
 }
 
 function OnGUI(){
 GUI.color = Color.grey;
 if(enter){
 GUI.Label(new Rect(Screen.width/2 - 75, Screen.height - 100, 150, 30), "Press E to Interact");
 }
 }
 
 //Activate the Main function when player is near the door
 function OnTriggerEnter (other : Collider){
 if (other.gameObject.tag == "Player") {
 enter = true;
 }
 }
 
 //Deactivate the Main function when player is go away from door
 function OnTriggerExit (other : Collider){
 if (other.gameObject.tag == "Player") {
 enter = false;
 }
 }

I know you need to add 2 vars with SoundOpen and SoundClose, here's my try at it:

 // Smothly open a door
 var smooth = 2.0;
 var DoorOpenAngle = 90.0;
 var soundOpened : AudioClip;
 var soundClosed : AudioClip;
 private var open : boolean;
 private var enter : boolean;
 
 private var defaultRot : Vector3;
 private var openRot : Vector3;
 
 function Start(){
 defaultRot = transform.eulerAngles;
 openRot = new Vector3 (defaultRot.x, defaultRot.y + DoorOpenAngle, defaultRot.z);
 }
 
 //Main function
 function Update (){
 if(open){
 //Open door
 transform.eulerAngles = Vector3.Slerp(transform.eulerAngles, openRot, Time.deltaTime * smooth);
 var soundOpened : AudioClip;
 }else{
 //Close door
 transform.eulerAngles = Vector3.Slerp(transform.eulerAngles, defaultRot, Time.deltaTime * smooth);
 audio.clip = soundClosed;
 }
 audio.Play();
 
 }
 
 if(Input.GetKeyDown("e") && enter){
 open = !open;
 }
 
 function OnGUI(){
 GUI.color = Color.grey;
 if(enter){
 GUI.Label(new Rect(Screen.width/2 - 75, Screen.height - 100, 150, 30), "Press E to Interact");
 }
 }
 
 //Activate the Main function when player is near the door
 function OnTriggerEnter (other : Collider){
 if (other.gameObject.tag == "Player") {
 enter = true;
 }
 }
 
 //Deactivate the Main function when player is go away from door
 function OnTriggerExit (other : Collider){
 if (other.gameObject.tag == "Player") {
 enter = false;
 }
 }

But for some wierd reason, the sound plays randomly, and I can't open the door, whats the problem here ?