[H] What interferes with hearing aids and how do you track them down?

[didymus7]

The contractor that lives with us (best way to do things!) has hearing 
aids that connect via bluetooth.  He periodically has problems with 
them.  He showed me once how the volume was going up and down by itself 
and at times, he has to reset them.  They work with his apple watch and 
Ipad.  As far as I know, the only place he has problems is in the house 
here.  Is there a good way to track down whatever is interfering with 
his hearing aids?

The primary place where he has problems is the living room. Beneath that 
is my computer room, but I've turned off wireless and bluetooth on the 
two computers down here.  So there is nothing using wireless or 
bluetooth directly beneath the living room. I only have a wireless 
printer running in the next room over and today I've shut off the 2.4 
ghz on my router, also in the next room.  Upstairs is another matter and 
I have to deal with my wife about that.

I've tried bluetooth and wireless apps on the phone but that doesn't 
seem to give me any info.  So, any ideas?

Thanks...Steve