Does a defendant have a right to demonstrate to the jury that he has a speech impediment?

In each case defendant contends that the trial court erred in denying him the opportunity to refute the complainant's identification by demonstrating to the jury that he had a speech impediment. Unquestioned is defendants' right to take the witness stand and testify, thereby waiving the privilege against self-incrimination and subjecting themselves to cross-examination about the incident itself, prior convictions, and prior bad acts ( see, People v. Betts, 70 N.Y.2d 289, 520 N.Y.S.2d 370, 514 N.E.2d 865). That is not what they sought to do, however; they wished to exhibit their voices to the jury. The relevance of the evidence they offered was not in what they would say, but in how they would say it.