I am being terrorized by strange high pitched sounds...

[Ramon Cota]

Every so often my apartment is being invaded by this quite loud high frequency ( 13,2 khz ) sound . It appears to change direction and amplitude fast , like some sonar or ultra sound weapon . It happens in the evening / early at night and i cannot locate the source of it, i am pretty sure its not a car but have no idea what device could that be.Does anyone recognise this sound and can help me ?
[ frequency is quite high so not everybody will be able to hear it, sorry old folks ]

 

[nerdstrike]

There are cat repelling devices that blare high frequency bursts after a motion trigger. I hear them across the street, but I don't think they'd have enough oomph to penetrate a house.

 

[Petrushka]

My suspect would be a bug repelling device plugged into a wall outlet.

Second thought is something needing oil.

Shopping mall stores used to have high frequency emitters to repel teenagers.