i don't know whether you happened to have heard or i don't know whether you happened to hear?上面的两种说法那一个正确?

i don't know whether you happened to have heard or i don't know whether you happened to hear?
上面的两种说法那一个正确?

第一种正确,第一种强调听到的结果,我不知道你是否碰巧听说了.这个“了”字是通过have heard来体现的