In People v. Fonville (1973) 35 Cal.App.3d 693, the prosecution introduced the tape of a jailhouse conversation between the defendant and his uncle. In it, the defendant said he had told the police he did not remember the crime because he "'was tanked up on pills . . . .'" He had taken "'12 or 14 reds . . . .'" Actually, though, he did remember at least the "'first part,'" of it, though not what happened "'after we left the cafe . . . .'" (Id. at pp. 706-707.) The evidence showed that jail officials had been asked to record the conversation. The defendant and his uncle were assigned to phone No. 30. "The recording room" was then told to start recording the conversation on phone No. 30. One Ronald Goodwin proceeded to record the conversation. Goodwin, however, did not testify; there was no other testimony that the tape was accurate or that the voices were those of the defendant and his uncle. (People v. Fonville, supra, 35 Cal.App.3d at p. 708.) The court noted that " . . . 'a writing may be authenticated by evidence that the writing refers to or states matters that are unlikely to be known to anyone other than the person who is claimed by the proponent of the evidence to be the author of the writing.' Applying this principle to the contents of the recorded conversation, it would appear that the statements regarding what had been denied to the police, what had been told to the police regarding the declarant's state of intoxication, quantity of intoxicants taken, and when the decedent had left the cafe, indicate that it was in fact appellant whose words were on the recording. They are matters that are unlikely to have been known by anyone other than the appellant. In effect, the conversation proves itself." (People v. Fonville, supra, 35 Cal.App.3d at p. 709.) The court also noted that a second tape featuring the defendant's voice was also in evidence, so the jury itself could recognize it. It concluded "that from the evidence surrounding the introduction of the tape, the contents of the conversation recorded thereon and the opportunity for the judge and the jury to compare appellant's voice on the two tapes, a sufficient foundation was established." (Ibid.)