var textFieldString = "Путь";
function Start () {

}

function Update () {

if(!audio.isPlaying && audio.clip.isReadyToPlay)
audio.Play();
}

function OnGUI () {
textFieldString = GUI.TextField (Rect (25, 25, 100, 30), textFieldString);

if (GUI.Button (Rect (20,60,80,20), "Play")) {
var www = new WWW(textFieldString);
audio.clip = www.audioClip;
}
}