As soon as I play music to listen to it the problem disappears. As soon as I pause the music the problem reappears.
If I open the graphic tool "song settings" the problem stops. As soon as I close it it reappears.
This problem is independent of the volume set by the user. Even with a volume set to zero the problem is present.
The problem is present after the boot from the login window.
The problem is present with the computer connected to battery or 220 V sector
If I make a search on google with "dell xps 9570 ubuntu "noise" " argument :
https://www.google.com/search?q=dell+xps+9570+ubuntu+%22noise%22&ei=zcS2Xe6JFtSo8gKXhKbQBA&start=0&sa=N&ved=0ahUKEwiupNqj4b7lAhVUlFwKHReCCUo4ChDy0wMIlwE&biw=2558&bih=1273
I dont find a functional solution, but I realize that other users are impacted by this problem.
The problem is very old, nobody solved it ;(
This post from 2014 talk about similar whistling in headphones
https://askubuntu.com/questions/457910/strange-noise-in-headphones-when-no-sound-is-played
The solution Below does not work well :
" Got the same problem on Dell XPS15 (9550, 2015 model in Xenial). Solved it in alsamixer and muting the loopback channel.
$ alsamixer
Navigating to loopback (all the way to the right, with → key) and setting it to Disabled using Mthe ↑ key. "
With Loopback Enable the whistling is his acute, with Loopback Disable the song is low-pitched.
It seems clearly to be Realtek ALC3266 driver problem... all PCs equipped with this sound card seem affected by this problem