Last night, I went downstairs to watch some tv but as I leaned over the couch to pick up the remote controller, I heard this high pitched sound. I listened and I thought it was coming from the speaker, but then as I went out into the hall, it seemed to get louder. I listened at the basement door but it wasn't coming from there. Then I was surprised to also hear it in the downstairs bathroom and also in the guest bedroom. Strangely enough, it was upstairs too and I thought it might be the thermostat, but it wasn't when I pressed my ear there.
Up in the bedroom, I said to Mark, "Do you hear that?" and he looked at me with surprise. It was loud up there too but he hadn't noticed and then I looked down and I was still holding the downstairs remote controller, which was out of batteries and emanating a high pitched squeal.