וְשָׁפַלְתְּ֙ מֵאֶ֣רֶץ תְּדַבֵּ֔רִי וּמֵֽעָפָ֖ר תִּשַּׁ֣ח אִמְרָתֵ֑ךְ וְֽ֠הָיָה כְּא֤וֹב מֵאֶ֙רֶץ֙ קוֹלֵ֔ךְ וּמֵעָפָ֖ר אִמְרָתֵ֥ךְ תְּצַפְצֵֽף׃
At ikaw ay ibababa; mula sa lupa ka magsasalita, at mula sa alabok ay hihina ang iyong pananalita. At ang iyong tinig ay magiging tulad ng sa espiritu ng patay mula sa lupa, at mula sa alabok ay huhuni ang iyong pananalita.
Rashi
from the earth shall you speak It shall appear as though the speech that comes out of your mouth comes from below the ground.
Ibn Ezra
And thou shalt be brought down. This applies to the words of Hezekiah’s messengers to Rabshakeh.8Comp. 36:11.
Rashi
shall your speech chirp to supplicate to Me, and because of your supplication, My mercies shall be aroused.
Rashi
צִפְצוּף is an expression of a whispering (var. weak) voice like the voice of small birds.