Deactivate Object Between 15-45 Seconds Of Not Visible

Unity Engine
1

Like the title says, is there a way to deactivate an object randomly between a given time? I know there’s something like OnBecameVisible but is there an OnBecameInvisible or something like that?
EDIT
After some messing around i managed to do something but is there a way to fade the audio out from the audio source I attached (not referenced in script).
Code

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class ChaseDeactivate : MonoBehaviour
{
    [SerializeField]
    private float delayBeforeLoad;
    [SerializeField]
    public GameObject killerObj;
    private float timeElapsed;

void Start()
{
delayBeforeLoad = Random.Range(15.0f, 45.0f);
}
private void Update()
{
timeElapsed += Time.deltaTime;


if (timeElapsed > delayBeforeLoad)
{
Destroy(killerObj);
}
}
}
2

Starting a Coroutine that fades audio, then disables the gameObject when done. If I remember correctly it’s faster to change the gameobjects visibility and disable scripts than it is to disable the gameObject entirely ( Haven’t been using Unity as much recently )

3

oh ok thanks