Larimer had been charged with incest.1 During his jury trial, his defense counsel objected to Detective Likens’ testimony relating to Larimer’s confession. This confession, the defense counsel contended, was involuntarily given by Larimer. The confession had been made by Larimer near the end of a four and one-half hour interrogation which ended after midnight in the prosecutor’s office. Larimer’s defense counsel was not present at the interrogation. The trial court overruled the objection to Detective Likens’ testimony. Later, the State offered a tape recording into evidence for the purpose of impeaching Larimer. The tape had been made during the four and one-half hour interrogation in the prosecutor’s office. It contained references to Larimer’s prior homosexual conduct as well as to his institutional treatment for mental illness at Muscatatuck. These references were not deleted before the tape was heard by the jury.
Larimer’s appeal to this Court raises the following issues for our review:
Issue One: Did the trial court err when it overruled the objection to Detective Likens’ testimony relating to Larimer’s confession?
Issue Two: Was the admission of Larimer’s confession harmless error?
*675Issue Three: Must the trial court take appropriate steps to delete immaterial and prejudicial matters placed upon a tape recording which are not germane to purpose of impeachment?
Our review concludes that a separate evidentiary hearing out of the presense and hearing of the jury is required on the issue of voluntariness. The trial court must make a separate determination on the voluntariness of Larimer’s confession before it is admitted into evidence as mandated by IC 1971, 35-5-5-1; Ind. Ann. Stat. § 9-1634 (Burns 1974 Supp.). We further conclude that the trial court’s failure to make a separate voluntariness determination before admitting Larimer’s confession into evidence was not harmless error. The immaterial and prejudicial matters on the tape, which were not necessary for impeachment purposes, should have been deleted by the trial court. We reverse the trial court’s judgment, and we instruct the trial court to grant Larimer a new trial.
I.
Voluntariness and Harmless Error
Detective Likens was called by the State to give testimony concerning Larimer’s confession. Larimer’s defense counsel objected for the reason that the confession was not voluntarily given by Larimer. An evidentiary hearing was requested upon the issue of voluntariness. The trial court, in the presence and hearing of the jury, overruled the objection without determining the voluntariness issue. This was error. IC 1971, 35-5-5-1; Ind. Ann. Stat. § 9-1634 (Burns 1974 Supp.) mandates the trial court to hear evidence out of the presence and hearing of the jury and to determine the issue of voluntariness before admitting confessions in evidence. IC 1971, 35-5-5-1 provides:
“In any criminal prosecution brought by the state of Indiana, a confession, as defined in section (5) [§ 9-1638] hereof, shall be admissible in evidence if it is voluntarily given. Before such confession is received in evidence, the trial judge shall, out of the 'presence and healing of the jury, *676determine any issue as to voluntariness. If the trial judge determines that the confession was voluntarily made, it shall be admitted in evidence and the trial judge shall permit the jury to hear relevant evidence on the issue of voluntariness and shall instruct the jury to give such weight to the confession as the jury feels it deserves under all the circumstances.” (Our Emphasis). Also see, Johnson v. State (1972), 258 Ind. 683, 688-89, 284 N.E.2d 517, 520.
The trial court’s failure to make “. . . a reliable determination . . .” that the confession was in fact voluntarily rendered constituted a violation of Larimer’s Fifth and Fourteenth Amendment rights, as well as a violation of IC 1971, § 35-5-5-1. Jackson v. Denno (1964), 378 U.S. 368, 377, 84 S.Ct. 1774, 12 L.Ed.2d 908. This federal constitutional error requires that we determine whether, as a matter of federal law, this error was harmless beyond a reasonable doubt under the circumstances of this case. Chapman v. California (1967), 386 U.S. 18, 87 S.Ct. 824, 17 L.Ed.2d 705; Greer v. State (1969), 252 Ind. 20, 245 N.E.2d 158; Bauer v. State (1973), 157 Ind. App. 400, 300 N.E.2d 364.
Some harmless error guidance can be gleaned from Chapman v. California, supra, 386 U.S. at 24, 87 S.Ct. at 828:
“. . . We, therefore, do no more than adhere to the meaning of our Fahy case when we hold as we now do, that before a federal constitutional error can be held harmless, the court must be able to declare a belief that it was harmless beyond a reasonable doubt. While appellate courts do not ordinarily have the original task of applying such a test, it is a familiar standard to all courts, and we believe its adoption will provide a more workable standard. . . .”
The Chapman Court characterized the facts as follows:
“. . . And though the case . . . presented a reasonably strong ‘circumstantial web of evidence’ against [the] petitioners ... it was also a case in which, absent the constitutionally forbidden comments, honest fair-minded jurors might very well have brought in not-guilty verdicts. Under these circumstances, it is completely impossible for us to say that the State has demonstrated, beyond a reasonable doubt, that the prosecutor’s comments and the trial judge’s *677instruction did not contribute to petitioners’ convictions.” 386 U.S. at 25-26, 87 S.Ct. at 829. (Our Emphasis).
When applying the federal harmless error standard, we must weigh the evidence against Larimer—absent his confession—and determine whether, beyond a reasonable doubt, an honest and fair-minded jury would have rendered a guilty verdict based solely on the remaining untainted evidence. See Greer v. State (1969), 252 Ind. 20, 245 N.E.2d 158.
Upon a review of all the evidence in the record—except Detective Likens’ testimony relating to Larimer’s confession—we are unable to conclude beyond a reasonable doubt that the constitutional error did not contribute to Larimer’s conviction. The State’s case-in-chief consisted of testimony from Larimer’s two minor daughters, Detective Likens and certain circumstantial evidence which tended to corroborate the testimony of the prosecuting witnesses. Larimer’s evidence consisted of his testimony which denied his daughters’ allegations. Additionally, he offered the testimony of his neighbors and a relative which tended to impeach the credibility of his daughters.
Absent Larimer’s confession, the jury’s resolution of Lari-mer’s guilt or innocence would have been substantially based on the credibility of the witnesses. In light of the powerful probative impact on the average juror of a defendant’s confession of guilt and the delicate balance of the testimony, it would be impossible for us to conclude that the constitutional error was harmless beyond a reasonable doubt. A new trial will be required.
II.
Impeachment by Tape Recording
The State attempted to introduce the tape recording of Larimer’s confession during its case-in-chief. An objection that the tape contained prejudicial matters which were immaterial to the confession was sustained. Later, when Lari-*678mer testified on his own behalf, he denied the act of incest and the confession. In rebuttal, the State again offered the tape in evidence to impeach Larimer. Again, the same objection was made to the tape, but the trial court overruled the objection. Larimer’s defense counsel followed up the overruling of his objection with a request for an in camera review of the tape so that the trial court could delete prejudicial and immaterial matters. The trial court refused defense counsel’s request. After playing the tape, the trial court admonished the jury to disregard the statements on the tape pertaining to Larimer’s history of homosexuality and mental illness.
After Larimer’s confession, Lamar v. State (1972), 258 Ind. 504, 282 N.E.2d 795, was decided by the Indiana Supreme Court.2 Lamar v. State, supra, establishes five specific standards for the admission of tape recordings.3 One of these five standards requires that the party offering the tape recording show that it “. . . does not contain matter otherwise not admissible in evidence. . . .” 258 Ind. at 513, 282 N.E.2d at 800. Therefore, an objection that the tape recording contains immaterial and prejudicial matters in addition to the matter at issue, requires the trial court to review the tape recording and to take such appropriate steps as necessary to delete the immaterial and prejudicial material. Our Indiana Supreme Court in Lamar v. State, supra, 258 Ind. at 510, 282 N.E.2d at 799, stated:
“If the objectionable portions can be eliminated, however, we see no justification for their exposure to the jury. To reconcile such matters, the trial judge, in the absence of the jury, should be furnished with a typewritten transcription of recordings and should *679also listen to the recording. If it is determined that the recording is generally admissible, a determination can then be made as to how best to insulate the jury from such portions, if any, as may be inadmissible.”
The judgment of the trial court is reversed with instructions to grant Larimer a new trial.
Garrard, J., concurs; Hoffman, J., dissents with opinion.. IC 1971, 35-1-82-1; Ind. Ann. Stat. § 10-4206 (Burns 1956).
. This appeal was fully briefed and submitted to this Court on September 10, 1974.
. The Lamar Court held that the admission of sound recordings should be preceded by a foundation disclosing that: (1) the recording is authentic and correct; (2) the testimony elicited was freely and voluntarily given; (3) all required warnings were given and all necessary acknowledgments and waivers were knowingly given; (4) the recording does not contain matters otherwise not admissible into evidence; and (5) the recording is of such clarity as to be intelligible and enlightening to the jury. 258 Ind. at 513, 282 N.E.2d at 800.