On the special status of this ghazal, see {485,1}.
The poor lover! Look at the degrees of his wretchedness. First, the beloved doesn't deign to recognize him as a person at all-- when he's in her presence, she notices only his voice. Second, the beloved is not convinced that the voice she hears is his at all-- it's only 'like' his. Third, the voice might even be 'like' that of someone else entirely-- the beloved may have a number of wretched, unmemorable lovers who afflict her with their laments and pleas. And fourth, no matter whose voice the present voice may (seem to) resemble, there's no hope at all-- the voice reminds her only, or emphatically, of the voice of 'that good-for-nothing'.
It's her very vagueness, her indifference tempered only by a remembered distaste, that is so poignantly funny. Or at least, I think the verse is funny; but I realize that a more serious-minded reader might decline to notice the humor. Here's another of those vexed questions of tone. See the next verse, {485,7}, for further discussion.
