Music play when MOVING..

Hi so,

What i want is music to play whenever the player is moving…
Here is my code.

#pragma strict

var music = false;

function Start () {



}

function Update () {


if(Input.GetKeyDown(KeyCode.W)||Input.GetKeyDown(KeyCode.A)||Input.GetKeyDown(KeyCode.S)||Input.GetKeyDown(KeyCode.D))
{

audio.Play();
}

if(Input.GetKeyUp(KeyCode.W))
{
	if(Input.GetKeyUp(KeyCode.A))
	{
		if(Input.GetKeyUp(KeyCode.S))
		{
			if(Input.GetKeyUp(KeyCode.D))
			{


				 audio.Stop();
			}
		}
	}
}

The problem i have is that the music restarts everytime the player presses W A S D even when the player is still moving.
I wanted it so when any of thos keys are down the music keeps on playing and when they are ALL UP then it stops.

Thanks

if(Input.GetKeyDown(KeyCode.W))
{
audio.Play();
}
else if(Input.GetKeyDown(KeyCode.A))
{
audio.Play();
}
else if(Input.GetKeyDown(KeyCode.S))
{
audio.Play();
}
else if(Input.GetKeyDown(KeyCode.D))
{
audio.Play();
}

             else    audio.Stop();

Try this:

if(Input.GetKeyDown(KeyCode.W)||Input.GetKeyDown(KeyCode.A)||Input.GetKeyDown(KeyCode.S)||Input.GetKeyDown(KeyCode.D)) { audio.Play(); }

else { audio.Stop(); }