How to play audio only if i stay within a collider, and not only once

I have a game object where i want to play a song only when the player is within a collider, but i dont want it to stop happening everytime i enter it again. I have this so far, but it still stops…

using UnityEngine;
using System.Collections;

public class SoundTrigger : MonoBehaviour {
public AudioSource source;
public AudioClip clip;
private bool isPlayed;

public void Awake ()
{
    source = GetComponent<AudioSource>();
    isPlayed = false;
}

public void OnTriggerEnter(Collider other) {

    if (!isPlayed)
    {
        source.Play();
        isPlayed = true;
    }

}

public void OnTriggerExit(Collider other)
{
    if (source.isPlaying)
    {
        source.Stop();
    }
}

}

you only need Start and Stop in enter and exit respectively, that’s it