1.
...do not be DEAF to me...
...if You be SILENT to me...
[חָרַשׁ] (charash)
[חֱשֶׁ֥ה] (chesheh)
Both mean "to be silent"
BUT
CHARASH denotes deafness, literally means "to remain deaf" to a call to speak or to act, to "give no ear" to such a call.
CHESHEH means "not to give expression" to a thought or an emotion, "to stop" a motion, "not to pay heed to an observation"...
The sense of the thought expressed in this verse would be as follows: “O You, upon Whom alone all the future depends, in whom I seek all the support of my life and the goal of my desires, do not withdraw from me without hearing my cry! If I were not to call upon You, and if You, too, were to look at my sad state without taking an interest or without concerning Yourself with it, then my life would have no more meaning and I would be as one whose path on this earth is nothing but a steady progress toward the grave.”