When Sasuke tunrned to orochimaru dose that make him a sound ninja?

No, It wouldn't. It just makes him a Missing Nin, hes still a Leaf Ninja. Sasuke would only be a Sound Shinobi if he went and got a headband. Orochimaru isn't actually offically a Sound Shinobi, Kabuto still is, If you look closely at Orochimaru, he has no headband, but if you look closely at Kabuto, you'll see a sound shinobi headband, but its not scratched out, meaning hes still part of the sound.

If you know Oro's past, you'd know hes actually a Leaf ninja, seeming he lived there long before going to the sound, of course, he never truely joined the sound, he joined the Akatsuki, and left when Itachi wouldn't give him his body. Sasori, who was upset his partner had left him, sent Kabuto after him as a spy, secretly meeting with him when he could.

After awhile, Oro broke Sasori's Jutsu, and when Sakura, Sai, Naruto, and the sensi that was filling in for Kakashi-sensi went after the spy, Oro attacked, and Kabuto was on Oro's side, not Sasori's, even though it truely wasn't Sasori, because Sakura and Lady Chiyo killed him a few episiodes before that.

Of course, these could be some spoilers for you, If I spoiled anything for you, I am truely sorry.

~Dosu Uchiha:D