AudioSource.playOnAwake  

if(!audio.playOnAwake) {
audio.Play(); // Play the clip if it wasn't set to play on awake
}

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
void Awake() {
if (!audio.playOnAwake)
audio.Play();

}
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

def Awake():
if not audio.playOnAwake:
audio.Play()