small texts with audio not copyrighted

I have been trying to find small and simple texts for beginners up to intermediate students that have an audio and are not copyrighted to be used on on-line lessons with my students. Does anyone know where I can find such material? I have asked graded readers publishers but they denied authorization. I am not native and I need audio made by native speakers. It's been a hard job finding it. Any help is welcome. Thank you!