I just moved into a new (to me) home. There are these two devices, one on the wall about a foot off the floor and another on the ceiling in the kitchen eating area. A small red light comes on behind the plate when there is a noise. What are they? Thanks. enter image description here
This is a Flush‑mount Glassbreak Detector. Here is a picture of another one that looks very similar made by Bosch.
EDIT: Just realized @BMitch deserves credit for this as he posted the correct answer in a comment before I posted this answer.