An āfah is an impediment that obstructs an activity. Silence may be the voluntary omission of speaking despite ability, whereas muteness or loss of speech ability concerns a restriction on outward articulation.
Two questions are distinct:
1. Has someone refrained from speaking despite being able to do so?
2. Is the physical capacity for producing words impaired?
Both examples concern articulated speech. In examining inner speech, they show that not expressing a meaning vocally and not possessing any such meaning are not the same condition.