Opinion
The accused was brought to trial before a general court-martial at Travis Air Force Base, California, on ten specifications alleging violations of Article 134, Uniform Code of Military Justice, 10 USC § 934. The specifications formed two groups of charges. Four specifications alleged the communication of obscene language by telephone to a female; four other specifications alleged the communication of a threat to the same female. The remaining two specifications dealt with a single telephone call to another woman.
Both females were married to service personnel occupying quarters on the base; and both were volunteer Red Cross workers at the base hospital. The accused was a patient at the hospital, receiving treatment for serious injuries sustained in an automobile accident. At trial, the woman involved in the two-specification group testified she received a single obscene and threatening call. She heard the caller make only a brief statement, before she hung up. Within the hour, she listened to a tape recording of another telephone call. While she was “reasonably certain” the voice of the male speaker was the “same” as the voice of the person who made the obscene call, she acknowledged that at the Article 32 investigation, she had expressed “reservation [s]” as “any reasonable person would.” The court-martial acquitted the accused of the two specifications in this group, but found him guilty of all charges alleging obscene and threatening calls to the other woman. It sentenced him to a bad-conduct discharge, confinement at hard labor for six months, and accessory penalties.
On this appeal, the accused contends he was prejudiced by several evidentiary rulings by the law officer. Two rulings resulted in the admission in evidence of the tape recording of a telephone conversation between the accused and the woman involved in the charges, as to which he was found guilty. A third ruling admitted in evidence expert testimony as to a comparison of “voiceprints” of parts of the tape of this conversation with extracts from a tape recording of a previous obscene telephone call.
The first of the obscene and threatening telephone calls was received on Saturday, January 22, 1966. Other calls were received the next day, and *186the matter was reported to the Air Police. With the assistance of the Pacific Telephone Company, a call received by the victim the following day was traced to a pay station in the basement of the hospital, adjacent to the Red Cross lounge. Lieutenant Robert C. Marcan, Chief of the Law Enforcement Branch of the base police, was notified while the call was still in progress. He went immediately to the site, arriving within four minutes of notification. No one was in the booth, but he observed the accused “walking out of the [Red Cross] lounge.” On February 3, the victim was at the lounge. The accused was also present. Apparently, he was an artist, and at the time was discussing with another woman a possible commission for a sketch of her child. The victim asked the accused to do one of her son, but he refused. In listening to the accused, the victim thought his voice “sounded like” the voice of the person making the obscene calls to her. During the afternoon of February 5, she received another call at home. The caller told her she should not have “called the Air Police, because he was . . . really going to get . . . [her] now.” This call was also traced to the pay booth in the basement of the hospital. On this occasion, Staff Sergeant Caskell Sauls and Lieutenant Marcan went to the hospital. Sauls saw the accused in the Red Cross lounge, and asked him for change of a quarter for use in a coffee machine. The accused said he had no change, but he directed Sauls to a place where it could be obtained. In Sauls’ opinion, the accused’s voice “appeared to be the same voice” he “had heard on the telephone with” the victim in one of the obscene calls. As a result, he asked a hospital corpsman to telephone the accused while he listened in on the conversation. This conversation convinced him the accused’s voice was the “same” as the obscene caller’s. He had the corpsman bring the accused to one of the hospital offices for questioning.
Sauls identified himself and Lieutenant Marcan as Air Police investigators. He informed the accused he was suspected of making obscene telephone calls, and advised him of his rights under Article 31, Uniform Code of Military Justice, 10 USC §831. He also advised him he had a right to counsel. The accused indicated he understood his rights; that he did not desire counsel; and he had no objection to being questioned.
After some questions about the accused’s acquaintanceship with volunteer Red Cross women workers at the hospital and the frequency of his use of the Red Cross lounge and the pay telephone, Sauls asked the accused if he would, “for identification of voice,” talk by telephone with a female who had received obscene calls. The accused agreed. A call was placed to the victim and the accused engaged in conversation with her. In the course of the conversation, the accused was asked to speak more slowly and to make his voice “hoarser” to simulate the speed and pitch of the obscene caller. The conversation was recorded on tape. At trial, defense counsel objected to the admission in evidence of this tape. Testifying in connection with the objection, the accused admitted he “realized” he “had a right to refuse” to talk to the lady, but he did “not mind”; it was his own “choice to make the phone call.” He maintained, and Sauls admitted, that he was not previously informed the conversation would be recorded; but he acknowledged that he “figured” it was taped.
The accused’s initial objection to admissibility of the tape was based on a contention that the warning as to his rights was legally insufficient because he was not directly advised that the telephone conversation would be taped. The objection was expanded on appeal to include an allegation of a denial of due process by the manner in which the Air Police secured identification of his voice by the victim.
So far as the scope of the preliminary advise is concerned, the question is not whether the accused knew the conversation was being recorded, but whether the conversation itself is admissible, Secret use of a record*187ing device by one party in conversation with another, in order “to make an accurate record” of the conversation, does not make testimony as to the content of the conversation inadmissible; -in other words, the content and the circumstances of the conversation determine its admissibility, not the fact that a device is secretly used to make a permanent record of it. Consequently, undisclosed recording of the conversation with the victim did not deny or abridge any substantial right of the accused. Osborn v United States, 385 US 323, 326, 17 L ed 2d 394, 87 S Ct 429 (1966); cf. United States v Greer, 3 USCMA 576, 13 CMR 132. The accuracy of the substantive part of the tape was not disputed. The failure, therefore, to inform the accused, preliminarily, that the test conversation would be recorded did not detract from the legal sufficiency of the warning given him as to his rights during the interrogation.
The due process aspect of the attack on the admissibility of the tape of the test call is constructed upon an analogy between the circumstances of that call and the procedure by which a voice identification was effected in Palmer v Peyton, 359 F2d 199 (CA 4th Cir) (1966). Appellate defense counsel contend the victim’s identification of the accused’s voice as the “same voice as the obscene call voice” was the inevitable result of a statement by Sauls that he had “a suspect” to whom she was to speak. However, neither the Palmer case nor the “psychology of suggestion” (see United States v Wade, 388 US 218, 18 L ed 2d 1149, 87 S Ct 1926 (1967)) is of any help to the accused.
In Palmer, the victim of a rape was not allowed to see the accused, but merely to listen to his voice. Her identification, therefore, was deliberately restricted to only one of many factors that bore upon the issue. In addition, the physical conditions under which the identification was made did not nearly approximate those under which the rapist spoke during the assault. The rapist wore a paper bag over his head; while the bag was in possession of the police it was not used in the identification process. Only the voice of the accused was submitted to the victim for consideration. Finally, at trial, the victim testified only to the station house identification, and made no effort to identify him in open court. In this case, the victim identified the tape of the obscene call of January 24, and stated that the voice was that of the person who had made all the calls to her. She further identified the voice in the recording of the test call of February 5, as that of the person who spoke to her at the request of Sergeant Sauls. Both tapes were played in open court. The witness testified that, to the “best of her knowledge,” the male voice in both tapes was that of the same person. She also declared that she talked to “two people on the phone” for “voice identification.” In her identification of the obscene caller, she referred to similar expressions used in each of the calls. Thus, unlike the situation in Palmer, the witness here was provided with an alternative choice and made an affirmative in-court identification of the obscene caller. Under the circumstances, there is nothing that even hints at the possibility the witness was influenced in her voice identification by the manner in which the test call was made, or by Sauls’ description of the person to whom the victim was to speak as a “suspect.” The test call was. presented as only a test of the general quality of the suspect’s voice. In fact, no effort was made to have him duplicate any of the obscene or threatening words used by the obscene caller, which might perhaps have had a tendency to establish a link between the two. There was no violation of due process by the manner in which the recording of the test call was made, or in the manner in which the victim identified the voice of the accused in the test call with the voice of the obscene caller.
Reference was made earlier to voiceprints of the January 24th tape and of the tape of the test call of February 5th between the accused *188and the victim. Voice identification of a person by human ear is a commonplace experience, and has long been recognized in the courts. United States v Wade, supra; United States v Whisenhant, 17 USCMA 117, 37 CMR 381. What is new in this case is that the voice identification was made by a machine which produced a picture of the voice. Appellate defense counsel contend that the scientific principles underlying the voiceprints are so uncertain in theory and practice as to require their exclusion from evidence as a matter of law. They maintain the record of trial demonstrates that voiceprints suffer from unreliability comparable to that which led to exclusion of the results of lie detector tests, United States v Massey, 5 USCMA 514, 18 CMR 138, and statements by' a witness made under the influence of so-called truth serums. United States v Bourchier, 5 USCMA 15, 17 CMR 15. The board of review considered the issue at length and determined that the voiceprints were admissible, despite some evidence in the record of trial of disagreement in the scientific community as to reliability of the machine which made the prints and the validity of the criteria used to interpret the prints. I reach the same conclusion.
The Manual for Courts-Martial, United States, 1951, indicates a witness may testify as an expert and express an opinion on a state of facts within his specialty if he “is skilled in some art, trade, profession or science or . . . has knowledge and experience in relation to matters which are not generally within the knowledge of men of common education and experience.” Id., paragraph 138e. Judged by that test, the Government’s expert witness, Lawrence G. Kersta, was, as pointed out below, a competent witness as to the process of making and interpreting voiceprints from samples of speech. However, the Manual’s definition of a witness qualified to testify as an expert is not entirely determinative of his competency to testify on a particular subject. In United States v Adkins, 5 USCMA 492, 496, 18 CMR 116, for example, we rejected the idea that years of investigating homosexuals qualifies a law enforcement agent to testify that homosexuals tell the truth, or that they are “ ‘products of broken homes.’ ” We pointed out that “expert opinion should bear some measurable relation to empirical observation.”
Mr. Kersta testified he held a Bachelor of Science Degree in Electronics and had been awarded a Master of Science Degree in Physics by Columbia University. For thirty-nine years he worked in the research department of Bell Laboratories, a research and development division of the Bell Telephone Company. His work was “mainly” in the field of speech and the determination of “individual characteristics of speech.” He was one of five persons at the Laboratory who, in 1943, invented a machine known as the “spectograph.” The spectograph analyzes sounds in various ranges and produces a picture of these sounds by means of a stylus tracing a line pattern. The printed picture of the sound pattern is called a spectogram. Starting in 1961, Kersta began to use the spectograph to experiment with voice identification of humans. In a two-year experiment, one hundred and twenty-three persons were selected from the same “dialectical area” to eliminate obvious voice identification factors. With a group of twelve high school students trained by Mr. Kersta acting as voiceprint interpreters, a single word from voice samples of the one hundred and twenty-three subjects was compared to voiceprints in a file of 14,000 prints obtained from the voices of employees at the Laboratory. The students achieved 96.5 percent success in identifying the speaker. Using a five-word sample, the students achieved 99.65 percent success. The results of this experiment were presented to the Acoustical Society of America and were published in a respected British scientific journal.
In March 1966, Mr. Kersta retired from Bell Laboratories and established his own firm to continue his work on voice identification and other sounds. Before this case, he had prepared between four hundred and five *189hundred voiceprints for use in “40 different cases” of law enforcement, and in various medical and psychiatric applications, ranging from voice analysis to determine disease in the vocal tract to the study of speech sounds as reflective of emotional stress. In the specific area of voice identification, he had obtained verification in “practically all of the cases” and, to his knowledge, had “made no mistakes.”
To establish a basis for voice identification, Mr. Kersta required a minimum of sixteen points of identity in the sound pattern on the spectogram of the questioned voice with the sound pattern of the known voice. He testified he compared the February 5th recording with the tape of the obscene call of January 24th, and found twenty-three points of identity. He also testified that uniqueness of the' voice of one individual from that of others is achieved by differences in the way each person uses the muscles or “articulators,” such as the lips and tongue, within his vocal cavity. These differences are manifested in the different sound patterns made by different voices.
Mr. Kersta’s testimony established that his system of voice identification had, experimentally and in practical application, demonstrated a high degree of accuracy and, further, that he was personally qualified to testify as an expert on comparisons of sound patterns made by human voices. True, two defense expert witnesses expressed reservations as to the complete reliability of Mr. Kersta’s system and procedures. The specifics of their reservations need not detain me. Courts have consistently recognized the admissibility of the testimony of experts in areas where there is neither infallibility of result nor unanimity of opinion as to the existence vel non of a particular condition or fact. For example, the difference of opinion among psychiatrists as to the mental condition of a particular person is very well known. See United States v Henderson, 11 USCMA 556, 29 CMR 372; United States v Carey, 11 USCMA 443, 449, 29 CMR 259. Identifying the author of a questioned document by comparison of the handwriting of the document with other handwritings made by known persons is commonplace in the courts, but it certainly cannot be said that all experts in the field and all techniques of identification are infallible. United States v DeLeo, 5 USCMA 148, 153, 17 CMR 148. In fact, visual examination of a questioned document with handwriting exemplars of the accused may lead the fact finders to an opinion different from that of the expert. United States v Privett, 4 CMR 392. Here, the tape recording of one of the obscene calls and the recording of the test call made by the accused were both before the court-martial. Each was played in open court. Since voice identification by ear is fully acceptable in the courts, the court members could thus determine for themselves the margin of error, if any, in Mr. Kersta’s expert opinion.1 With the board of review, therefore, I am satisfied that the shortcomings of Mr. Kersta’s voice-print system did not render his opinion inadmissible.
Appellant’s final assignment of error charges the law officer with improperly curtailing the testimony. of one of his experts. The witness, Dr. Frank R. Clark, was a senior research psychologist at the Stanford Research Institute, “working in the problem of speech transmission and voice recordings.” Dr. Clark testified he was familiar with various techniques used in voice identification, including Mr. Kersta’s. He acknowledged the Ker-sta system “has been demonstrated to result in far better than chance performance in the identification of talkers,” but, in his opinion, it was still “far from what we’d term highly realistic.” In his testimony he referred to certain research in a Massachusetts *190laboratory which attempted “to duplicate” Kersta’s efforts in a “loose sense.” On objection by trial counsel, Dr. Clark was not allowed to testify to the published results of this study. Appellate defense counsel contend the law officer’s ruling was prejudicial because it would have demonstrated that the Kersta system had not had the “general acceptance of the scientific community.” See United States v Ford, 4 USCMA 611, 16 CMR 185.
Appellate defense counsel concede the Massachusetts study was not admissible as “proof of the matters in the study,” but they insist the results would have been of “immeasurable value” in helping the court members understand the reasons for Dr. Clark’s rejection of Kersta’s claim of near-total accuracy in identification by means of his voiceprint system. See Manual for Courts-Martial, supra, paragraph 138e; 32 CJS, Evidence, § 546(63), page 269; Wigmore, Evidence, 3d ed, § 1700; United States v Williams, 16 USCMA 210, 36 CMR 366. Assuming that the law officer should have allowed defense counsel greater latitude in establishing all the underlying factors that led Dr. Clark to his opinion, still no prejudice appears in the particular rulings challenged by the accused.
Dr. Clark, as noted earlier, testified to his familiarity with the work of others in the field, including the experimentation in the Massachusetts laboratory. Dr. Clark admitted the Massachusetts efforts were only in a “loose sense” similar to those of Kersta’s. Consequently, the results of that study could hardly have contributed materially to Dr. Clark’s opinion as to the fallibility of Kersta’s system. Dr. Clark’s testimony made crystal clear that his criticisms of Kersta .were predicated directly upon his own work in the field of voice identification and the apparent deficiencies of Kersta’s, as revealed in Mr. Kersta’s writings and speeches. Assuming he credited the opinions of the Massachusetts experts (cf. Paschal v United States, 306 F2d 398 (CA 5th Cir) (1962)), the record leaves no doubt that these had only peripheral influence in the development of his own opinion. The record also indicates the court members took the tapes and a recording machine into the closed session deliberations. In his final argument, defense counsel had urged them to listen to certain parts of the tapes. I am reasonably sure, therefore, that the court members considered not only Dr. Clark’s testimony as to the fallibility of Kersta’s system, but determined by ear identification whether his criticisms were justified in this case. In light of these circumstances, the restrictions on Clark’s testimony as to the particulars of the work of others in the field present no fair risk of prejudice to the accused.
The decision of the board of review is affirmed.
Judge Kilday concurs in the result.