// Use this for initialization
    void Start()
    {
        theAM = FindObjectOfType <AudioTest>();

        if (newTrack != null)
        {
            theAM.ChangeBGM(newTrack);
        }
    }
 void OnTriggerEnter2D(Collider2D other)
 {
     if (other.gameObject.tag == "Player")
     {
         if (newTrack != null)
         {
             theAM = FindObjectOfType <AudioTest>();
             theAM.ChangeBGM(newTrack);
         }
     }
 }