And he said, Who hath ears to hear, let him hear. St. Luke (Luke 8:8) bus a stronger word than ( ἔλεγεν) "he said." He (Luke 8:8) has ( ἐφώνει) "he cried." Our Lord uses this expression, "he that hath ears to hear," etc, when the subject-matter is figurative or obscure, as though to rouse the attention of his hearers.
He has "ears to hear" who diligently attends to the words of Christ, that he may ponder and obey them. Many heard him out of curiosity, that they might bear something new, or learned, or brilliant; not that they might lay to heart the things which they heard, and endeavor to practice them in their lives.
And so it is with those who go to hear sermons on account of the fame of the preacher, and not that they may learn to amend their lives; and thus the words of Jehovah to Ezekiel (Ezekiel 33:32) are fulfilled, "And, lo, thou art unto them as a very lovely song of one that hath a pleasant voice, and can play well on an instrument: for they hear thy words, but they do them not."