I gave ear to your reasons - Margin, "understandings." The meaning is, that he had given the most respectful attention to the views which they had expressed, implying that he had been all along present, and had listened to the debate.
Whilst ye searched out what to say - Margin, as in Hebrew, words. It is implied here that they had bestowed much attention on what they had said. They had carefully sought out all the arguments at their command to confute Job, and still had been unsuccessful.

I waited for your words; I gave ear to your reasons - Instead of תבונותיכם tebunotheychem, your reasons, תכונותיכם techunotheychem, your arguments, is the reading of nine of Kennicott's and De Rossi's MSS. The sense, however, is nearly the same.
Whilst ye searched out what to say - עד תחקרון מלין ad tachkerun millin; "Whilst ye were searching up and down for words." A fine irony, which they must have felt.

Behold, I waited for your words; I gave ear to your reasons, whilst ye searched out (g) what to say.
(g) To prove that Job's affliction came for his sins.

Behold, I waited for your words,.... With great desire, with great eagerness and earnestness, in hope of meeting with arguments fully satisfying and convincing; he waited for them, as for the rain, and the latter rain, to be revived, refreshed, and edified therewith; and he patiently waited until they had done speaking:
I gave ear to your reasons, or "understandings" (r); endeavoured to get into the sense and meaning of their words; not only attended to what they did say, but to what he thought they meant to say: some are not so happy in their expressions; and yet, by what they do say, with close attention it may be understood what they aim at, what is their drift and design; this Elihu was careful to attain unto, not barely to hear their words, but penetrate, if possible, into their meaning:
whilst ye searched out what to say; for they did not make their replies to Job immediately, and say what came uppermost at once, but they took time to think of things, and to search out for the most forcible arguments to refute Job, and strengthen their cause; it is very probable they made a pause at the end of every speech of Job's, and considered what was proper to be said in reply, and, perhaps, consulted each other.
(r) "usque ad intellignetias vestras", Pagninus, Montanus, Cocceius, Schultens; "usque ad sensa vestra", Beza, Junius & Tremellius.

Therefore Elihu was present from the first.
reasons--literally, "understandings," that is, the meaning intended by words.
whilst--I waited until you should discover a suitable reply to Job.

11 Behold, I waited upon your words,
Hearkened to your perceptions,
While ye searched out replies.
12 And I attended closely to you,
Yet behold: there was no one who refuted Job,
Who answered his sentences, from you.
13 Lest ye should say: "We found wisdom,
God is able to smite him, not man!"
14 Now he hath not arranged his words against me,
And with your sentences I will not reply to him.
He has waited for their words, viz., that they might give utterance to such words as should tend to refute and silence Job. In what follows, עד still more emphatically than ל refers this aim to that to which Elihu had paid great attention: I hearkened to your understandings, i.e., explanations of the matter, that, or whether, they came forth, (I hearkened) to see if you searched or found out words, i.e., appropriate words. Such abbreviated forms as אזין = אאזין (comp. מזין = מיזין for מעזין, Proverbs 17:4, Ges. 68, rem. 1, if it does not signify nutriens, from זוּן) we shall frequently meet with in this Elihu section. In Job 32:12, Job 32:12 evidently is related as an antecedent to what follows: and I paid attention to you (עדיכם contrary to the analogy of the cognate praep. instead of עדיכם, moreover for עליכם, with the accompanying notion: intently, or, according to Aben-Duran: thoroughly, without allowing a word to escape me), and behold, intently as I paid attention: no one came forward to refute Job; there was no one from or among you who answered (met successfully) his assertions. Every unbiassed reader will have an impression of the remarkable expressions and constructions here, similar to that which one has in passing from the book of the Kings to the characteristic sections of the Chronicles. The three, Elihu goes on to say, shall not indeed think that in Job a wisdom has opposed them - a false wisdom, indeed - which only God and not any man can drive out of the field (נדף, Arab. ndf, discutere, dispellere, as the wind drives away chaff or dry leaves); while he has not, however (ולא followed directly by a v. fin. forming a subordinate clause, as Job 42:3; Psalm 44:18, and freq., Ew. 341, a), arrayed (ערך in a military sense, Job 33:5; or forensic, Job 23:4; or even as Job 37:19, in the general sense of proponere) words against him (Elihu), i.e., utterances before which he would be compelled to confess himself affected and overcome. He will not then also answer him with such opinions as those so frequently repeated by them, i.e., he will take a totally different course from theirs in order to refute him.