To begin with, there are two Silences and not one: There is the Silence of the Mouth and, in addition, the Silence of the Mind. The former does not necessarily accompany the latter, but the latter always accompanies the former. That is, one can be silent "in-the-mouth" while not, at the same time, also being silent "in-the-mind." On the other hand, one who is silent "in-the-mind" is, at the same time, always silent in-the-mouth. Thus, there are three types of Lomaidim (Hebrew = "Learners"):
"The wise man does not speak in the presence of one who is greater than he in wisdom; he does not interrupt the speech of this companion; he is not hasty to answer; he questions and answers properly, the point; he speaks on the first point first, and on the last point last; regarding that which he has not learned he says, 'I have not learned;' and he acknowledges the truth when he hears it. The opposites of these traits are to be found in a stupid person." (Pirke Avoth 5:9)
The "hearing-impaired" individual, on the other hand, is one who appears to be silent, while all the while arguing, comparing, and responding to the other in his mind. Despite the silence of his mouth, his ears neither hear nor understand because the chatter of his mind deafens them as if with cotton. It is like the very old joke of the man who encounters his friend on the street:
Such a person, of course, is only one step removed from the "fool" in that although "deaf," he can at least be made conscious of not hearing and thereby correct it, but only when he removes the bananas from his ears- -- that is, when he is willing to silence his mind as well as his mouth, which requires an heroic act of consciousness that the Ego is often ill equipped to perform. But this "mind" we speak of is like a wild ox, made even stronger by the Ego, that must be tamed, as we see in the ancient Ox-Herding Pictures of Rinzai Zen Buddhism.