I am starting to see a correlation

I do not want to see this correlation, because it makes no sense and because implies I should limit my already limited lifestyle in fairly unpleasant ways, but here is the suspicion. It looks like audiobooks are bad for my shoulder. (Books or music. Any mp3 I listen to on purpose. But in practice, it turns out to be mostly books.) I got out of the habit of listening to anything after I got my ears pierced, but went back to it in January.