Strange buzz/chirp noise coming from anything plugged in

[wqt]

Hi, recently I noticed a repeating static kind of sound (here's a recording, its kind of quiet - Vocaroo | Voice message - https://vocaroo.com/i/s1BmtSek9HLs) coming from the power supplies of pretty much anything plugged in in my flat. (first noticed in my computer, then my monitor, charging bricks, thermostat, etc.) Also, it only occurs in the evening - starting somewhere between 4:30-5:00PM and lasting throughout the night - at least until 3AM, not sure about later; it always stops by the morning though. Its always very regular in its repeating, although in some time periods I have heard it at a slower rate. An electrician came (when the sound was not occurring), tested my breaker/outlets, and said everything looked fine.

He thought it could be interference from outside lights, but the lights come on earlier, 4PM at latest I think. I don't have anything on a timer or turn on anything only in the evening. Recently I noticed the sound is also audible through speakers/headphones connected to a plugged-in device (only post-5PM). Was wondering if anyone has ever heard of anything similar, or what could be looked into to make it stop. Thanks.

 

[buzzlightyear]

How strange have you rang Any body else ,ask you local priest to pop in.

 

[MFS Electrical]

Do you have storage heaters or an immersion heater set to come on about that time?

 

[Bob Geldoff1234]

The recording sounds like some sort of electronic interference.Do you have any wi-fi extenders?
What I would do is switch off other circuits at the fuse board one by one.So try switching off the lighting breaker and listen if it's gone and then move onto the shower,cooker and other socket circuits.Once you have completed all circuits except your main socket circuit,then start unplugging the appliances on that circuit including spurs for boilers etc.
Do you have solar panels?
Once you have identified that it's not coming from your flat then it could be coming from your neighbours flats?

 

[HappyHippyDad]

@wqt Perfect advice above ↑

Once you notice those sorts of sounds they really get on your nerves!

 

[freddo]

At my parents house on any wound transformer there would be a blip in the 50Hz hum once per second. It still happens as far as I know.

 

[static zap]

Some smart meters make irritating noises ,
(but possibly only when internal display is active)
--Need to spy on building from outside , to see if anyone's light activity matches your pattern.--
(Then expand search to further neigbours)

 

[Nebu1a]

dimmer switch maybe?