public AudioClip Fire1;
public AudioClip Fire2;
private bool flag; // переменная для определения какой именно звук нужно проиграть

void Update() {
if(Input.GetMouseButtonDown(0)) {
if(flag) {
audio.clip = Fire2;
audio.Play();
}
else if (flag == false) {
audio.clip = Fire1;
audio.Play();
}
}

using UnityEngine;
using System.Collections;

public class DubStep : MonoBehaviour {
public Transform Dubstep;
public bool shot;
public Light Halo;
public bool show;
public bool sound;
public Transform dubstep;  
public AudioSource a ;
public AudioSource b ;  
public ControllerD Player;
public MouseLook camera;
// Use this for initialization
void Start () {

}
void Awake(){
b.enabled = true;
a.enabled = false;    
}
// Update is called once per frame
void Update (){   
if(Input.GetKeyDown(KeyCode.Mouse0)&& shot){  
shot =!shot;                              
}
if(shot){
audio.Play();
}else{
if(Input.GetKeyDown(KeyCode.Mouse0)){    
shot = shot;    
}
}
}
void OnTriggerStay(){
if(GameObject.FindWithTag("DubSound")&& Input.GetKeyDown(KeyCode.E)){  
show = !show;  
if(show){    
Player.enabled = false;
camera.enabled = false;
}else{
if(!show){     
Player.enabled = true;
camera.enabled = true;      
}
}
}
}
void OnGUI(){
if(show){     
GUI.Box(new Rect(100,0,640,480),"Музыка для DubStep Gun");  
if(GUI.Button(new Rect(100,100,100,50),"Dub step Music")){
a.enabled = true;  
b.enabled = false;    
}
if(GUI.Button(new Rect(100,150,100,50),"Thousand Foot Krutch - War of Change")){
a.enabled = false;     
b.enabled = true;                              
}
}
}  
}