Need help with managing my scripts..

Well... Its kinda hard to explain for me. But im trying to put all my sound into one script/Gameobject named sound. But my current issue is how can i make...

void OnTriggerEnter() or OnCollisionEnter()

Work with my gameobject "Ball" without my script being attached to it. ): I figured out how to get a int from other scripts, but this isnt so easy or is it? My code for the sound script

 using UnityEngine;
 using System.Collections;
 
 public class Sound : MonoBehaviour {
     public AudioClip impact;
     public Collider ball; // Tried to drag the ball into her guessing was worth a shot (:
     AudioSource audio;
 
     void Start() {
         audio = GetComponent<AudioSource>();
     }
 
 
     void Update() {
         GameObject Goal = GameObject.Find ("Goal2"); //Getting a int from another class
         Score scoreCheck = Goal.GetComponent<Score>();
         if(scoreCheck.score == 2) {
             audio.PlayOneShot (impact, 0.7F);
         
 
         }
     }
 
     void OnCollisionEnter(Collision col) { //Current code im having a problem with
             audio.PlayOneShot (impact, 0.7F);
     }
 
         }

Im just starting in learning so sorry if im not the best (: