Pi-top[4] constant static noise on built-in speaker

I just recently got myself a pi-top[4] with an already built in rpi4.

I now realized, that the built in speaker constantly emits a static noise.

Lowering the volume doesn’t change the static. It is quite, but can clearly be heared when but near the ears.

At first I even thought the pi-top4 has 2 built in fans…

Is this normal behaviour? If yes, are there any configuration options (maybe in config.txt) that would eliminate this static noise?

On the net I found some posts about disable_dithering or audio_pwm_mode=2, but I didn’t want to experiment stuff before aksing here.

Hope someone can help.