PlayRandomSound.cs

using UnityEngine;
using System.Collections;

// place on a GameObject with an AudioSource component
[RequireComponent(typeof(AudioSource))]
public class PlayRandomSound : MonoBehaviour {

	public AudioClip[] sounds; // assign in inspector

	// Use this for initialization
	void Start () {
		AudioSource audioSource = GetComponent<AudioSource>();
		audioSource.clip = sounds[Random.Range (0, sounds.Length)];
		audioSource.Play ();
	}

}