Audio sync with explosions

I was following one of the live training PIT: Cinematic and trying to figure out how to get the explosion audio to sync with the script. There is a 3 sec delay from when character starts walking until the explosion(visual) but the explosion(audio) plays as soon as “play” button is pressed. I have tried putting the listener on the car, the character and the camera. I have tried switching play on awake to on and off. In the off position, no sound is played. Not too familiar with scripting but I tried adding a pub var to a script that instantiates and regulates(time delay scale) the explosion but I am not getting anywhere. Here is the script:

using UnityEngine;
using System.Collections;

public class ExplosionCar : MonoBehaviour {

public GameObject explosion;
public AudioClip nukeIt;

// Use this for initialization
void Start () {
	Invoke ("explode", 3f);
	Invoke ("nuke", 3f);

void explode(){
	Instantiate (explosion, transform.position, Quaternion.identity);
	Destroy (this.gameObject);

void nuke(){
	//not sure what I need to put in here. Have tried 
	audio (AudioClip.nukeIt);

If you think that you have done everything to increase the audio and it did not become high.

  1. Audio Source is very far from the listener.(Add an audio source to the main camera and play the sound there)

  2. The audio was recorded at a low volume.

    //play audio on main camera generally where Audio Listener is present