The problem is probably your reed or mouthpiece set up. When a mouthpiece table is not sealing, it can make the reed squeak, especially on hard attacks. Also, if the reeds are warped or the heart of a reed is not sealed onto the mouthpiece, squeaks can occur. Unfortunately, it could also be the saxophone itself that is not sealing properly, but I would look into getting different reeds and a mouthpiece first. The stock mouthpiece isn't very good, and you will be much more satisfied with a different one (maybe a selmer, link, ect..) Also try rico royal reeds or vandorens, because they may give u a better response than the LaVoz reeds. Make sure you are soaking your reeds from tip to tail in your mouth before you put it on a mouthpiece.