Well, depending on the insulation in your apartment, I DO think it’s possible you could be hearing your neighbor’s aids squealing all night long. What if he just takes the aids out at night and doesn’t turn them off? If they’re rechargeables, they should be nested in the charging base, in which case they are supposed to turn off and charge up, but I had an issue with my Phonak rechargeables where they would WAIL even when placed in the charging box. Hubs heard it alright, but I’d have slept right through it.
Seriously, approach your neighbor and ASK HIM: “Do you turn your aids off at night? Cuz I’m hearing a feedback noise coming from your apartment.”
When I lived in an older duplex growing up, we’d hear my dad and brother talking down in the basement! The heat ducts were our “intercom” and we’d yell through them: “DINNER’S READY!” so they’d know to come upstairs. We had our landlord’s floor between the basement and our unit on the top floor … so yes, I do think there are factors whereby you may be hearing your neighbor’s aids at night.
It is definitely NOT a good idea to have these aids squealing all night long. Tell your neighbor it’s like running a Ferrari at 210 mph for 24hrs! At some point, you’ll burn the engine out.
Good luck pinpointing the puzzling sound and DO let us know where it’s coming from.