(help) Door sound

You placed your audio.Play() call inside the for loop when closing the door.

 var IsOpen : boolean = false;
  
 var CanOpen : boolean = false;
  
 var Volume : float = 0.5;
  
 function Start () {
    audio.volume = Volume;
 }
  
 function Update () {
    if(Input.GetKeyUp(KeyCode.Q) && !IsOpen && CanOpen)
    {
        Opening();
        IsOpen = true;
        audio.Play();
    }
  
    else if(Input.GetKeyUp(KeyCode.Q) && IsOpen && CanOpen)
    {
        Closing();
        IsOpen = false;
        audio.Play();                 //Added this
    }
 }
  
 function Opening () {
     for (var i = 0; i < 100; i++)
     {
         transform.Translate(-0.017,0,0);
  
         yield WaitForSeconds(0.01);
     }
 }
  
 function Closing () {
     for (var i = 0; i < 100; i++)
     {
         transform.Translate(0.017,0,0);
  
         yield WaitForSeconds(0.01);
         //audio.Play();                And removed this
     }
 }
  
 function OnTriggerEnter (other : Collider) {
     if(other.gameObject.tag == "Player")
     {
         CanOpen = true;
     }
 }
  
 function OnTriggerExit (other : Collider) {
     if(other.gameObject.tag == "Player")
     {
         CanOpen = false;
     }
 }
  
 @script RequireComponent(AudioSource)

Also a word of advice. Never name variable names with capital starting letters. Like:

CanOpen is generally not good practice.

canOpen is generally better and is a capitalization style called camel case.

It is of course a matter of preference.