Commentary for Berakhot 118:9

ואלא קשיא ל"ק הא דשמע משמע הא דחזא מחזי

Still there is a contradiction! No, there is not; [the formula in the Mishnah] applies when he heard [that it had been raining], the other when he actually sees it.

Abraham Cohen Footnotes to the English Translation of Masechet Berakhot