There is one other portion of the evidence relevant to this category and that's the evidence of Ms Nguyen and I will deal with that in a moment. Ordinarily, witnesses aren't allowed to give their opinions in court. They confine their evidence to their own observations. This is because it is you who are the judges of the facts and so usually it's only your opinion that is relevant.
However, the law says that people with specialised knowledge or training are allowed to give their opinions about matters within their field of expertise, if that may assist [in your] in determining your decision.
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Now, I want to give you some directions regarding the other opinion evidence, or expert evidence, and that is the evidence of Ms Nguyen. She gave evidence of her work and opinion in respect of the material contained in the [telephone intercept] material. Recall that she told you that her work was done in different stages.
First, she listened to the [telephone intercepts] as the calls were happening and the SMSs were sent. She did that as they were going on, at that time, or in real time, I think, as was described. And also when she returned to work the following morning. She provided a summary to investigators of the content of that material.
Second, she was directed to translate some of the SMS messages and phone calls, the subject of the [telephone intercept] material. And this resulted in the transcripts that you have in your Jury Book 2. In respect of both of those two tasks, those first two tasks, they were undertaken by her in April to June 2013.
Now, the final stage of her work was in respect of some of the [telephone intercept] material and that occurred in April of this year, 2015. She was required to compare the voices of each of the accused on their records of interview, with some of the material in the [telephone intercepts], which she had previously translated and she gave you an opinion in respect of that.
Now, in respect of the first two parts of the exercise that she undertook, her evidence can be treated like that of other experts. She was called as an expert in the translation of the Vietnamese language. Her expertise in the field was not challenged. However, it was argued that there were limitations on her translations, given the manner in which she did that task. That i[s], it was not a straight word for word exercise, rather she took into account the context and nuances of the Vietnamese language. It is a matter for you whether you accept the translations as provided by her.
As part of this second part of the task, that is when she was doing the transcriptions, she was required to distinguish between the voices that could be heard. And you will recall her evidence regarding the attribution of individuals to the voices. So she had 'Male 1', 'Male 2', 'Unknown male', terms throughout that material.
Now this was part of her expertise in translating, that is, being able to distinguish voices and attribute voices to conversations in material with which she was familiar. And you will recall her evidence regarding the same male as '392', or 'bacsi', that is B-a-c-s-i. Again, it is a matter for you whether you accept the attributions that she gave, based on listening to the [telephone intercept] material.
Now the final stage of her work, that is attributing a specific individual to the voice on comparing the record of interview of the accused. She attributed the voice of Tony, as referred to in the call to the taxi, you might recall that being one of the calls in the collection that you have, as that of Tony Chang, on listening to his record of interview. She did not attribute the voice of Tran on listening to the record of interview, to any of the calls that she heard.
Ordinarily she would not have been able to give that evidence relating to voice recognition, but she could because of her familiarity with the voices, having done the exercise that she did.
As I have told you, witnesses are not usually allowed to give their opinions in court. They must usually confine their evidence to their own observations, and that is because it is you who are the judges of fact and usually only your opinion that is relevant.
So you must, in this last aspect of her evidence, remember that it is only her opinion and you are not bound by it. Like any other evidence, you can accept or reject it. You are able to do that by comparing the voices, if that is something that you choose to do. It really is a matter for you.
She was able to give the evidence because she had a broader experience with the calls than you did. She heard a lot more of the calls than you have got. So if I, in the course of the charge, talk about her opinion, when I describe someone's - sorry, if in the course of the charge I talk about her opinion, or if I describe someone's voice is said to be that of Mr Chang or the other male, as [sic] same as call 392. I am only giving her opinion evidence in that regard, the description that she gives and it is up to you whether you accept or reject that description.
However, you should keep in mind the fact that the voice identification or recognition evidence is really again just one piece of circumstantial evidence and must be considered in light of all of the other evidence in the case. I refer back again to the direction I gave you regarding reasonable inferences.
It is very important though, that you understand certain matters in respect of voice recognition evidence. There are two aspects to the identification evidence or voice recognition evidence that I want to give you some directions about.
The first is the voice identification of Chang and the other male, as same as call 392, or bacsi on those calls that you listened to. That is what this relates to, and I am pretty sure I have made that clear from the bit that I just directed you about.
The prosecution says you should accept Ms Nguyen's evidence that the voices she attributes to Tony and the other man, are the voices of Tony Chang and the other man. Now it is for you to determine whether the voices, as set out by Ms Nguyen is the voice of Tony Chang and of the same person in call 392, but I give you this warning. The experience of the law has shown that the task of voice identification must be performed with great care. That is because it can be very difficult to make an accurate identification of voices. There may be problems in clearly hearing the voices, particularly if the recordings are of poor quality or, as in this case, some of them are of very short length.
Consider the level of familiarity with voices that she had at the time that she made the voice recognition. There was a considerable time difference of two years between when Ms Nguyen was working intensively with the material, and her attribution of unknown individuals to when she compared that to the voices in the record of interview.
In addition, the relevant people may have been talking in very different circumstances and at different times, about various matters, using different words and tones of voice. It can make it difficult to ensure that any identification comparison evidence or voice recognition evidence is accurate.
It is important that you undertake or treat the evidence of the comparison of voices with special care and you should be especially cautious before relying on Ms Nguyen's evidence in relation to that comparison.
Having given you that general warning about the dangers or difficulties with voice comparison, I want to then look at specific factors that might affect the reliability of such evidence and there are two main factors that you must examine when making a comparison. (1) The quality of the material and (2) The nature of the voices to be compared. You should consider these factors carefully along with any other relevant factors when making a comparison.
As to quality, was there clarity in the voices that she compared; were there similarities in the circumstances of the recordings, that is, listening on the [telephone intercept] material and comparing the material within the [telephone intercepts], but also then comparing the [telephone intercept] material with the material in the record of interview or the police interview.
You will recall that Ms Nguyen was comparing voices that she heard on tapes, mostly in a foreign language. She was comparing that to voices that she heard of particular accused speaking to police officers during the course of [the] investigation. Was there really enough material for her to make a comparison with the record of interview? You could consider the quality of the recording. How good was the quality and quantity of content in the calls when you were comparing the voice to voice that she heard in the interview?
Counsel in their addresses pointed out a number of factors that they submitted were also relevant to the voice identification issue. Ms Nguyen was limited in her experience in comparing voices as she was required to do in this instance.
She did this task well after, I should indicate that these relate to her comparison between the [telephone intercepts] and the record of interview as opposed to the [telephone intercepts] themselves. She did this task well after she was acquainted with the voices during her work in 2013 and she had heard many other voices during her translation tasks in the two years in between. She couldn't remember the calls that she used to compare with the record of interview, though she said that there were about 20 out of the 37. Some of the calls were very short, only being one or two words.
In the record of interview itself, some of the responses were similarly just as short. There were instances where she didn't identify Mr Chang as the speaker, when the prosecution has said that it was him. That's in relation to calls 467, 468, 473 and 475.
Similar arguments were presented on behalf of Mr Tran in respect of the recognition evidence. These focus more so though, on the exercise of comparing within the telephone intercept material itself, given that she indicated that she did not identify Tran through the record of interview.
The other aspect you should consider is the nature of the voices. That is, the nature of the voices you are comparing. Are the voices particularly distinctive? Were similar words used? Was there a similar manner of speaking throughout? Are you relying too heavily on the fact that both the voices spoke with a foreign accent, or in this instance, of course, a foreign language. It can be very difficult to distinguish between two unfamiliar voices that speak in a similar language.
You will recall the evidence regarding her differences in the description of voice, and also the criticisms made. You will recall her evidence that she added some of the characteristics that she had previously identified in respect of Mr Chang's voice only in her evidence, and on previous occasions, she hadn't attributed it to being - I think the word was squeaky or creaky - it's one of the other, but I think that she did indicate that.
In respect of Mr Tran there was nothing, no particular characteristic that helped her identify the voice, rather it was possible for her to be able to distinguish the voice from the other as opposed to any specific characteristic in respect of Mr Tran.
Look at the way the people spoke to the police and whether that would be in a different kind of way in which you'd speak to someone on a phone in a normal conversation. People speak differently on the phone to the way they'd do in more formal circumstances you would think, like when they're talking to a police officer.
Consider the issue of whether, because it's in a foreign language - that is, Vietnamese - that the comparison exercise is much more difficult. All of these things are factors that you need to consider in determining whether or not you accept this aspect of Ms Nguyen's evidence.
As I say, the experience of the law is such that you need to take special care with voice recognition evidence because people can be quite honest and quite convinced they're right, but they're quite wrong.
So bear in mind those factors when you come to look at the voice recognition evidence. However, as I have indicated in respect of a number of pieces of evidence, you should keep in mind the fact that this recognition evidence again is just a piece of circumstantial evidence, and it should be considered in light of the other evidence in this case.[10]