var track1 : AudioClip;
var track2 : AudioClip;
   
audio.clip = track1;
audio.Play();
   
var audio1Volume : float = 1.0;
var audio2Volume : float = 0.0;
var track2Playing : boolean = false;
   
function Update() {
     fadeOut();
   
     if (audio1Volume <= 0.1) {
         if(track2Playing == false)
         {
           track2Playing = true;
           audio.clip = track2;
           audio.Play();
         }
   
         fadeIn();
     }
}
   
function OnGUI()
{
     GUI.Label(new Rect(10, 10, 200, 100), "Audio 1 : " + audio1Volume.ToString());
     GUI.Label(new Rect(10, 30, 200, 100), "Audio 2 : " + audio2Volume.ToString());
}
   
function fadeIn() {
     if (audio2Volume < 1) {
         audio2Volume += 0.1 * Time.deltaTime;
         audio.volume = audio2Volume;
     }
}
   
function fadeOut() {
     if(audio1Volume > 0.1)
     {
         audio1Volume -= 0.1 * Time.deltaTime;
         audio.volume = audio1Volume;
     }
}

using UnityEngine;
using System.Collections;
public class wer : MonoBehaviour {
      public int ab = 0;
      werTS werT;

      void Start () {
       werT = new werTS ();
      }
      void Update () {
       ab = werT.abOt;
      }
}

using UnityEngine;
using System.Collections;

public class werTS : MonoBehaviour {
      public int abOt = 90;

      void Start () {
           
      }
           
      void Update () {
       }
}

using UnityEngine;
using System.Collections;
public class Test : MonoBehaviour {
     void OnCollisionEnter2D(Collision2D other) {
         Debug.Log("Collision. Вход");
     }
     void OnCollisionExit2D(Collision2D other) {
         Debug.Log("Collision. Выход");
     }
     void OnTriggerEnter2D(Collider2D other) {
         Debug.Log("Trigger. Вход.");
     }
     void OnTriggerExit2D(Collider2D other) {
         Debug.Log("Trigger. Выход");
     }
}