Question about Aukey Pa-T15

No, not at all. It plays the cello in its spare time, but basically I haven't heard any disturbing noises so far. I have used both the Quickcharge port and the normal ports and have not noticed anything like that.

I can confirm. My unit pipes weakly when no load is connected. As soon as a device is attached, it quietens totally.
The sound is complex, like a pulsating multi-pitched whistle, so weak that I need to bring the charger to my ear to perceive it. It is not a problem at all, at least not for me.

For the record, I am 55. My hearing is normal.

No perceptible acoustic noise.

I also have an Anker (different model) and it does the same. Now the device is in the basement...

No, I've never heard that. But I'm 60 .... maybe I don't hear so well anymore.

Mine doesn't whistle audibly either. But I built it into the sofa. High-frequency sounds can be easily muffled.

I cannot confirm the whistling. My unit does not make any sounds when idling or under load.

My poodle accidentally swallowed mine. Since then he has been whistling at a high frequency. He is already quite distraught and the other poodles in his group avoid him because of it. I wanted to return the device, but poodles don't accept them. Bad service!