don't talk loud in the library.

aloud,loud,loudly 这些副词均含有“高声地、大声地”之意.
aloud → 强调出声,能让人听见,无比较级.用于修饰cry,call,shout等动词时,有高声之意.
loud → 指声音响亮,高声说话,一般放在所修饰的动词后面.
loudly与loud含义相同,可放在动词之前或之后,用以说明声音的强度,含“喧闹”的意味.
可见都可以的.
如：
He doesn't talk loudly and laugh loudly in public.他不在公共场合高声喧哗,大声发笑.