Playing Sound when it Collides with more than One Object

Sorry if this has already been posted about. I'm not very good with the audio side of things, and I'm trying to get it so that, when an object hits a different the walls, the same sound is made. However, all the tutorials on the subject that I have come across so far, have only helped in playing the sound once, and then never again afterward.

This is my most recent attempt:

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. [RequireComponent(typeof(AudioSource))]
5. public class SoundOnCollision : MonoBehaviour {
6.  
7.     public AudioSource audio;
8.  
9.     void Start() {
10.          audio = GetComponent<AudioSource>();
11.  
12.  
13.     }
14.  
15.     void OnCollisionEnter (Collider other)
16.     {
17.         if (other.gameObject.tag == "Wall 2") {
18.             audio.Play();
19.         }
20.    
21.     }
22. }

Any chance I could get some advice? Thanks in advance!

 

Triggers might be a better idea.