how to make sound continue where it left off

Hello,

I'm having trouble finding info about what I am trying to do, here is some very simple code I have to start and stop sound OnTriggerEnter/Exit:

 using UnityEngine;
 using System.Collections;
 
 public class TriggerSound : MonoBehaviour {
     float timeStart;
     float timeEnd;
 
     void OnTriggerEnter(Collider other)
     {
         if (other.gameObject.tag == "Player")
         {
             AudioSource audio = GetComponent<AudioSource>();
             Debug.Log("Trigger entered");
             audio.Play();
         }
     }
 
     void OnTriggerExit(Collider other)
     {
         if (other.gameObject.tag == "Player")
         {
             AudioSource audio = GetComponent<AudioSource>();
             Debug.Log("Trigger exited");
             audio.Stop();
         }
         
     }
 }
 

What I want to figure out how to do (if possible) is pick up playing the sound where it left off, another words, if I enter the collider and don't exist for 21 seconds, when I enter the collider and trigger the sound again it will start playing at 21 seconds into the sound file, not begin again at the start of the sound file as it does now.