What will the Chacham hear, and what will he increase?
Rashi: He will hear these Meshalim, and add learning to his Chachmah.
Malbim: A Chacham received the laws of Chachmah from his Rebbeyim, or via engaging in Torah. Chachmah is very wide; it has no limits. Via these Meshalim, his ear will acquire many details that were not explained in the Torah and the tradition of Chachamim.
What is the difference between a Chacham and a Navon?
Rashi: A Chacham heard teachings. A Navon adds to a Chacham's Yedi'ah, for he can understand a matter amidst another matter, and adds to what he heard. Malbim - he generates [new] knowledge from knowledge via comparisons and acquires Tachbulos.
What are "Tachbulos"?
Malbim: He generates derivatives of ideas via a chain of many comparisons. Via this Sefer he will acquire many introductions, and learn to build and make many comparisons with his power of Binah - one from another, and another from it, to widen his Binah.