Pesach Haggadah, Magid, Rabban Gamliel's Three Things:
רַבָּן גַּמְלִיאֵל הָיָה אוֹמֵר: כָּל שֶׁלֹּא אָמַר שְׁלשָׁה דְּבָרִים אֵלּוּ בַּפֶּסַח, לא יָצָא יְדֵי חוֹבָתוֹ, וְאֵלּוּ הֵן
פֶּסַח, מַצָּה, וּמָרוֹר.
Rabban Gamliel was accustomed to say, Anyone who has not said these three things on Pesach has not fulfilled his obligation, and these are them:
the Pesach sacrifice, matsa and marror.
I have bolded the word said (in both Hebrew and English). Must these 3 items be said orally, or can a person use sign language to "say" these things, and still fulfill the requirement?