Probation officer’s opinion on speaker in intercepted calls was properly admitted even though the calls were in Spanish and officer had only heard defendant speak English. During Ortiz’s jury trial for drug offenses, the trial court considered argument by the prosecutor and Ortiz on whether Ortiz’s federal probation officer, McGlynn, could offer opinion testimony identifying Ortiz’s voice on intercepted calls. On these calls, Ortiz primarily spoke Spanish, with some English words dispersed throughout. McGlynn said that she had spoken to Ortiz on the phone and in person at least 16 times over six months and that he had a distinctive voice and a tendency to say “all right” often during his conversations. They had spoken only in English. The trial court admitted the testimony. On appeal following his conviction, Ortiz challenged the admission of McGlynn’s testimony because she did not speak much Spanish and had only heard Ortiz speak English. Held: Affirmed. Where the government offers a tape recording of the defendant’s voice, it must make a prima facie case that the voice on the tape is actually the defendant’s. Lay opinion is permissible so long as the witness has the requisite familiarity with the speaker. McGlynn’s familiarity with Ortiz’s voice was substantially more than the minimal familiarity the federal rules of evidence require for admission of lay voice identification testimony. Ortiz’s challenges went to the weight rather than the admissibility of McGlynn’s testimony, and the jury was properly instructed so.