Hi, you can use the mediaRenderer events, its a enhanced version of Speaker notify with sound, try it
Right now SmartThings TTS its not working, you must to use voiceRss, ivona or alexa, alexa not need to get an api key, but its slower, I suggest to sign with voiceRss its free and support 300 msg per day, try it
[Updated] Media Renderer Events, play messages, radio stations, tracks, sounds