An expert in enhancing audio recordings explained to the International Criminal Court (ICC) the steps he took to make speech more audible in recordings that Ugandan security agencies made of intercepts of communications between various commanders of the Lord’s Resistance Army (LRA).
Alan Robert French told the court the recordings, made on cassette tapes, were of poor quality and were made with a tape recorder placed near the device used to intercept LRA radio communications. French said he focused on making the speech more audible without distorting it as much as possible.
He said some of the cassette tapes the Office of the Prosecutor (OTP) gave him were clearly copies and not the original recordings. French said he did not analyze the cassette tapes further to determine whether the recordings had been tampered with because he was not asked to do so. He said his assignment was just to enhance them.
French testified on November 13 during the trial of Dominic Ongwen, a former LRA commander. Ongwen has been charged with 70 counts of war crimes and crimes against humanity. He has pleaded not guilty to all counts.
The Uganda People’s Defense Forces (UPDF) and Uganda’s internal intelligence agency, the Internal Security Organisation (ISO), intercepted LRA communications for almost two decades. In January, an ISO member, Witness P-059, testified about that agency’s intercept program. In February, a UPDF member, Witness P-003, testified about the military’s intercept program. During the testimonies of these witnesses, prosecutors played excerpts of some of the recorded intercepts in which various LRA commanders were heard reporting attacks or talking about other things.
In October, Xavier Laroche, a forensic officer with the OTP, testified about the work he and a colleague, Sabina Zanetta, did in enhancing the audio of 106 cassette tapes. Laroche said their work was based on a framework French had developed.
On November 13, French told the court that when he worked on enhancing the recordings from the Ugandan security agencies, he used equipment from the company he works for, CEDAR, and manipulated the levels to raise that of speech and reduce background noise. He said cassette tapes can have a lot of “white noise or hiss.”
“I have been doing this for 33 years. I think I have got a pretty good idea when to remove enough noise but leave enough noise,” French said.
He said reducing too much the level of noise could affect the speech in a recording.
“A good example is a person’s voice may start to sound muted,” French said. “So, you have to be very aware of not damaging the speech by over-processing these signals too much.”
“Could it be that content is suppressed?” asked Presiding Judge Bertram Schmitt.
“If you were careless, content could be suppressed. One of the things that we have done is also supply enhanced but also unenhanced material,” replied French.
During his testimony on November 13, French spent most of his time answering questions from Michael Rowse, a lawyer representing Ongwen. This is because French was testifying under Rule 68(3) of the ICC Rules of Procedure and Evidence, and his statement and its annexes were entered into evidence. This also meant that prosecutor Julian Elderfield only had a handful of questions for him to clarify his statement and then Elderfield finished his examination-in-chief.
Under Rule 68(3) a witness has to be present in court and not object to his or her statement being used as evidence in a trial. When he was presented with his statement and its annexes, French told the court he did not object to them being used as evidence. Also under Rule 68(3), the witness should be available for questioning by lawyers and judges. Trial Chamber IX allowed French, whose witness number is P-242, to testify under this provision in a November 18, 2016 decision.
French told the court he began his career as a merchant navy radio officer and later joined London’s Metropolitan Police in 1994. He said most of his work while at the Metropolitan Police was enhancing audio recordings. He told the court during his busiest year he handled more than 300 cases. French said he joined CEDAR in 2010 where he is sales manager and an expert and forensics specialist.
Rowse questioned French about technical issues such as frequency response, sample rate, bandwidth, his choice of format to store the digital files of the enhanced recordings, and how he handled cassette tapes that had been recorded at a high volume, creating distortion.
Ongwen’s lawyer also asked French whether he spoke any of the languages of northern Uganda or had a background in linguistics. French said no to both questions. Rowse then asked whether he was aware of the emphasis made on particular letters in Acholi, a language spoken in northern Uganda and commonly used in the LRA. French said he was not aware.
“From your experience working with intercepted audio, has this ever been a consideration?” asked Rowse.
“Yes. I think certainly with certain languages there are different emphasizes on types of sounds that are used, and if I get material in, which is of a foreign language, then I am always very careful about the enhancement work that I do,” replied French.
“If your treatment changed the meaning of the recording you would not be aware of this?” asked Rowse.
“I would not,” answered French.
“How could this happen that the meaning is changed in a recording?” asked Judge Schmitt.
“Altering the material is probably not that realistic unless you actually edited that phrase out,” replied French.
“It’s possible that, for example, when I spoke earlier about suppressing S sounds you may change the meaning of the word by suppressing something like that. You would need to be a native language speaker,” French explained further.
He said one of the measures he took to make sure he had not changed the meaning of a recording was, “I compared the enhancement that I had done with the unenhanced material all the time.”
Rowse also asked French ways one would detect if a cassette tape had been altered. French said noting the clicks on the tape was one indicator because an analogue tape recorder leaves, “an electric fingerprint on the tape.”
“You will record a click on the tape. That click can be quite a good sign of what you are dealing with. There should only be one set of clicks,” French said.
He said the most obvious sign was if there was, “a lump of sticky tape in the middle.”
French said technology made altering recordings, particularly digital ones, easier.
“The premise that someone can change audio in their bedroom is probably quite a real one and what people tend to do now, those who do digital authentication, is go into code,” French said.
Rowse played for French three excerpts of one of the unenhanced recordings from the Ugandan security agencies. He asked French to mark the point he heard any discontinuity. French marked a discontinuity on each of the three excerpts.
French told the court this did not mean the tapes had been altered. He said the discontinuity could be explained by the recording being stopped or paused. He said he would have to know the make of the recorder that was used to record the tapes, make test tapes to compare with before reaching any conclusions.
French concluded his testimony on November 13. Next to testify was Witness P-351.
A transcript of French’s testimony is available here.