IPA: //sʌbˈvoʊkəl//
KK: /sʌbˈvoʊkəl/
Describing actions related to speaking or forming words without producing sound, often involving the movement of the lips or other speech organs.
She practiced subvocal reading to improve her comprehension without speaking aloud.
Subvocal → It is formed from "sub-" (meaning under or below) and "vocal" (from Latin "vocalis", meaning relating to the voice). The word "subvocal" refers to sounds or speech that are produced under the level of audible voice, often as silent speech or internal dialogue.
Think of 'sub-' meaning 'under' and 'vocal' relating to 'voice' — subvocal means something that is under the voice, like silent speech.