I sometimes hear noises that aren't actually there?

It doesn't happen often.. and this is actually just the second time it's happened in my memory. But earlier this year, or late last year, I heard a very short series of what sounded like short text notifications. I know for a fact it wasn't my phone, and I was alone in my house at the time. It wasn't all clumped together, but it spaced out through a span of maybe four minutes.

And now, just a few minutes back, I heard what sounded like the ringtone of a home phone. It sounded like it was behind me just barely and to the left, but I'm in my room, we don't have a home phone and my radio was off.. it rang just once, and it's a little unnerving. I'm also home alone now.

I don't really know what's going on, it's a little weird and it kind of makes me nervous when this happens. I was very awake both times these happened, so it can't really be anything like.. dreaming.

If anyone has any idea or.. really, anything, I'd be appreciative.