Chirping noise

1) check for a battery back-up Carbon Monoxide alarm - might be signalling a low battery.

2) Might be a frisky CRICKET (literally an insect looking to attract a mating companion).

Just in case it is a smoke detector or Carbon Monoxide detector either battery powered or battery back-up signalling a low battery (some older CO detectors first chirp at lowlevel detections below the "emergent" threshold from the upstairs or common wall neighbor - Make a visit to either/or and see if they might have an chirping alarm. If either has been vacant for a while contact your building maintenance/superintendant or property manager and/or the Condo Board and express your concern.

Do you have a battery back-up device (like for a computer, a life-safety alarm system - like "i've fallen and can't get up system, or similar in the condo? These tend to chirp whenever they are tripped into the ON position and/or if they are unplugged but not turned off.

A personal alarm system, battery powered travel alarm clock, etc. that was put away with the batteries still in place might be stored somewhere (like a suitcase, in an adjacent closet?)old smoke detector, or a really older style CO alarm that doesn't have a user-replaceable/accessible battery, and the dull, intermittant chirp because the batteries are all but dead - same might even be in the upstairs or common wall neighbor's unit - or in a common area, or attached garage/systems closet area. A neighbor's parakeet or other pet bird, or a cricket could be hiding in any of those areas as well. Finally, does your parent wear a hearing aid?

It turned out to be an old water heater with an overflow sensor that was beeping, very odd. Thanks to all that replied.

Chirping sound every 25 seconds coming from laundry room