how to reproduce a sound effect while loading a scene

how to reproduce a sound effect while loading a scene? I would like to play a sound effect when moving to the next scene, but it does not play. I already tried with method DontDestroyOnLoad but it doesn't work and I get this error: NullReferenceException: Object reference not set to an instance of an object LevelLoader.LoadNextLevel () this is my script to manage sounds:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class SoundManagerScript : MonoBehaviour
 {
     public static AudioClip clikSound, shootSound;
     static AudioSource audioScr;
     // Start is called before the first frame update
     void Start()
     {
         
         clikSound = Resources.Load<AudioClip> ("clik");
         shootSound = Resources.Load<AudioClip>("shoot");
         audioScr = GetComponent<AudioSource> ();
         
     }
 
     // Update is called once per frame
     void Update()
     {
         
     }
     public static void PlaySound(string clip)
     {
         switch (clip)
         {
             case "clik":
                 audioScr.PlayOneShot(clikSound);
                     break;
 
             case "shoot":
                 audioScr.PlayOneShot(shootSound);
                 break;
         }
     }
 }

and this is the script for switching between scenes:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.SceneManagement;
 
 public class LevelLoader : MonoBehaviour
 {
     public Animator transition;
 
     public float transitionTime = 1f;
 
     
     static AudioSource audioScr;
     public void LoadNextLevel()
     {
         DontDestroyOnLoad(audioScr.gameObject);
         SoundManagerScript.PlaySound("shoot");
         StartCoroutine(LoadLevel(SceneManager.GetActiveScene().buildIndex + 1));
         
         
 
     }
     
     
     IEnumerator LoadLevel(int LevelIndex)
     {
 
 
         
         transition.SetTrigger("Start");
         yield return new WaitForSeconds(transitionTime);
         SceneManager.LoadScene(LevelIndex);