I live in a conservative area and have never witnessed anyone with ear buds on at mass.
About 10 or so years ago at our old parish liturgical committe sent out notice in our bulletin about what is proper as mass. It said that they aren’t handing out bulletins before mass because of distractions of people reading it during homily and that one should not read the Missal during mass but focus on the altar especially for the gospel reading. There were other things in it I forget but it was writren in a way that assumed that all congregants were using items to distract themselves from woshipping.
An mp3 player would really send them over the edge, and tying this with your other thread, yes I believe they would verbally attack you for this.
We belong to a more sedate parish now. Lol.