private string defaultErrMsg = "Missing scene json file: <>. Check the file name and directory again.";     // error message to be displayed on canvas

        private void Awake()
        {
            // Obtain current scene name and locate the correct json file; set default error message
            string currentSceneName = UnityEngine.SceneManagement.SceneManager.GetActiveScene().name.ToLower();

            sceneJsonFile = "voiceovers_" + currentSceneName + ".json";
            //sceneJsonFile = "voiceovers_bluewhale.json";
            defaultErrMsg = defaultErrMsg.Insert(defaultErrMsg.IndexOf(':') + 3, sceneJsonFile);

            instance = this;

            // assign audio source for voiceovers
            if (!audioSource)
            {
                audioSource = GetComponent <AudioSource>();
                if (!audioSource)
                {
                    audioSource = gameObject.AddComponent <AudioSource>();
                }
            }

            if (sceneJsonFile != null)
            {
                InitializeVoiceoverManager();
            }
        }
 private void OnDestroy()
 {
     instance = null;
 }