Ok!!
Thank you very much for this answer!!

Hi, Mathias81. Welcome to cmo!

The noise you're hearing is normal.  LSDJ has an automatic battery saving mode that turns on when ever music isn't being played.  It causes the extra noise.  You'll most likely get used to it pretty quickly but if you just can't stand it anymore you can do the "prosound mod" which will eliminate almost all of the noise but can make your gameboy a little harder to use with headphones.  Just google or search on here for "prosound mod" and you'll get tons of results.

Hi
I send this message, because i have a probleme of backnoise when i'm using Lsdj ( lsdj4_7_3-stable) on a classic Gameboy.
Lsdj is on "64m usb smart card". When i turn one the software, there is a back noise (kind of crackling) during the time were the name of the staf creator of LSDJ apear on screen. After the noise stop but it s here every time using the cross for direction.
The backnoise deseapear when i start the music, but it's very boring when i spend long time on it for composing.
I try to install other version of lsdj  but it's still the same probleme.
Maybe there is someone to help me?
Thank you very much

Mathias