The Casebook of a Forensic Linguistics Consultant

This is a slightly revised version of a fairly informal talk given in 1991 at York to the International Association for Forensic Phonetics which was to become later the now flourishing International Association for Forensic Phonetics and Acoustics.

I have the impression that even those of one's colleagues in the linguistic disciplines who are ready to airily dismiss the activities of a forensic linguistics consultant as not really scientifically respectable, or even as not ethically desirable, often have no real idea of what kinds of things an individual practitioner like myself gets up to. I refer to forensic "linguistics" because I often find that, even in a case that requires mainly phonetic analysis, my overall judgement is best based also on other linguistic considerations. And, as will become clear below, a few of my cases have been quite non-phonetic.

When I arrived at Leeds in 1970 to join the Department of Phonetics, which was required by the University to merge with the Department of Linguistics in 1978, there was not, I suspect, a great deal of activity in the UK in the forensic linguistics field. At any rate, I knew of very little. Though I did know that some was undertaken by our Head of Department the late Peter MacCarthy. The field was about to expand very considerably as a consequence of the greatly increasing availability and popularity of non-professional recording equipment.

The only case of his I remember hearing anything of was one in which certain men, making themselves out to be dealers, requested to be allowed to adjourn to an adjacent room of the central Leeds hotel that they were in to examine and discuss privately what I believe was bullion they were pretending be about to make an offer for. The owners of the bullion could hear through the intervening door the muffled voices of the prospective purchasers for some time. When either impatience or suspicion got the better of them, they entered the room, only to find that they'd been hearing a recording of the thieves, who were by then well on their way with the "swag". I don't recall whether MacCarthy's analysis of the recording was able to help towards tracking them down or not. No departmental records of his cases survived.

The earliest case I remember being drawn into myself was the notorious so-called "Black Panther" kidnapping of a young heiress in 1975 which led tragically, and no doubt accidentally, to her death. A ransom demand was received by her family in the form of a tape recording made by a speaker whose accent could readily be assigned to a quite small area of the Midlands known as the Black Country. Copies of the original and of tapes of suspects were brought to my colleague Stanley Ellis and myself by the Staffordshire police for us to see if we thought that any of them was the same person. As with the Geordie voice of the Sutcliffe case, the speaker could not be identified at the time. He was, in fact, not the kidnapper, but someone attempting to cash in on the situation.

At that time, MacCarthy and one other colleague, the late Brian Annan, were responding to any requests made to my Department; but, when they'd both departed, I found myself seeming to be the only member of the department willing to attempt to provide the police and various legal practices with such help. In the subsequent two decades or more I dealt with a fair number of cases of many different kinds. They were more or less evenly distributed over the years. In only about one case in five did I find myself involved in any attendance at court, and in only about half of those occasions called to testify in the witness box, though there were many occasions when I was saved from that necessity at the very last moment. I often attended court to be on hand so that the barrister involved could, if desired, consult me during the course of the hearing.

There was one case early on at the Liverpool Crown Court in which the linguistic witness for the defence had actually already been heard. Then the two opposing barristers asked the judge if the court could be adjourned for some minutes for them to confer. During that time the prosecution showed the defence the evidence I had provided. When the court resumed, the defendant changed his plea to guilty!

The cases with which I was concerned were largely in the North, on both sides of the Pennines, but also in the Midlands, the Home Counties and even on occasion in Wales or Scotland. They were mostly in large cities like Newcastle, Manchester, Liverpool and Sheffield and of course in Leeds. About two thirds were at the request of one police force or another; the rest were mainly for defence counsels; though a few had no necessary police involvement.

One of this last kind concerned a large Northern industrial company within which sexual harassment of certain female staff by indecent anonymous phonecalls had been occurring. The calls were known to be internal only, and the management had contrived to get one of them recorded. They thought they'd recognised the voice on their tape, but they wisely decided to take advice before accusing the person suspected. They were able to obtain a sample of his telephone conversation for me to compare with the indecent caller. When I heard the two tapes, I could quite understand why they'd thought that the two voices might belong to the same person; but my advice was that, although I was not completely certain, I would have said that they were different speakers. A couple of weeks later the caller was caught redhanded and it was not the person they had suspected.

Another non-police matter was an enquiry from a businessman a member of whose secretarial staff was discovered to be divulging industrial secrets to a rival company. He'd identified the person concerned and had made a tape of her calling this other firm. However, the telephonist at the firm giving the firm's name said it so unclearly that he was quite unable to make it out and, of course, was very frustrated in consequence. He sent me the tape and I couldn't make it out either! Nevertheless, I was, after a fair amount of listening, able to tell him with some confidence that the expression used consisted of either 4 or 5 orthographic syllables; and that, if it was 5, the middle one was almost certainly the word "and". I could also identify all the four vowels, the first of which was the second sound of the first word. Also, I was certain of the very first sound. This was the /k/ phoneme and so had to be spelt c – or, just possibly, k or ch . I also gave him some examples of the sort of expression it might be, while admitting that, though they had the right rhythmic pattern to be looking for, I didn't in fact think any of them was the actual phrase used. I left it to him to go through what lists of possible rival companies he could lay his hands on!

I'd be disappointed if I thought he hadn't been successful, but I never felt like bothering him with questions as to how he got on. It's one of the regrettable dissatisfactions of doing this sort of work that, as often as not, one gets to know very little of the ultimate outcome of a case. I've felt before now peculiarly grateful to a solicitor who's bothered to mention such a thing, and especially to the busy policeman who takes the trouble to ring me up and say what has finally happened in a case. However, on reflection it's perhaps no bad thing, because I don't know of any case in which my judgement was proved to be at fault, and if I'd known more of the outcomes, I no doubt wouldn't be able to say that!

Most of my cases were at least very largely phonetic; but a few of them were of a kind which is now no doubt becoming much less common since the fairly general implementation of the 1984 Police and Criminal Evidence Act, under which it became legal, and indeed is now customary, for interviews with accused persons to be tape-recorded. The type of case I mean is known, informally at least, as "verballing". This means that the accused alleges that incriminating words have been put into his mouth in the reporting police officer's written account of the questioning.

One of these cases I found to be inconclusive; but in another I was able to take the opportunity to talk to the accused myself. I felt well able, after that conversation with a type of member of society with whom I don't often enjoy any extended verbal intercourse, to challenge some of the prosecution's assertions. Certain of the expressions that had been noted by the police interviewer allegedly "contemporaneously", as the customary police jargon has it, or, as he'd put it himself with a more attractive simplicity, "straight into his pocket book", were, I felt quite sure, more literary turns of phrase than the accused person would have been capable of formulating, leave alone inclined to employ. I had no doubt that the person with whom I had had my conversation was indeed a member of the criminal fraternity, but that didn't justify his being misrepresented!

Another case which involved no comparison of voices was one in which the police force concerned were pretty desperate to find any sort of clue that had any hope of leading them to a persistent and violent rapist. More than a little reluctantly, I agreed to examine the reports of the victims who'd supplied comments on his speech. Rather predictably, I was able to say hardly anything that I, at least, considered useful. I'm glad to say the man was later caught.

In another case, I was supplied with a tape and three letters all of which conveyed the same type of politically motivated bomb threat. I felt able to link them together quite confidently and also to venture suggestions, among other things, about the person's level of education, regional origins and on something that might be considered as a possibility for her profession. In all, it didn't seem much to me, but it did seem to be well received by the officers who'd requested it. Apparently, it had strengthened their feeling that a certain person or persons should be kept on their list of suspects. The only other of the cases in which vocal and written material were of similar importance was the notorious so-called Yorkshire Ripper hoax on which I have published articles dealing with the non-phonetic evidence. See the item "The Yorkshire Ripper Hoax Tape" on this web-site.

There were various other bomb-threat cases, some of which, unlike the one previously mentioned, were merely hoaxes. Another was aimed at extorting money from the proprietors of a supermarket. Extortion was a motive common to the various blackmail cases, in one of which it was combined with the malicious persecution of a disaffected spouse.

In one of the blackmail cases, the would-be extortioner attempted to conceal his identity by adopting a Scottish accent. However, although generally fairly convincing, he used certain pronunciations that would be hardly likely to be heard from any Scotsman. These included the word "you" in an obscure-vowel weakform to which he appended an "intrusive" linking /r/ and the word "put" with its vowel "hypercorrected" to rhyme with "cut".

There were various marital disaffection cases, all involving malicious telephone calls containing threats. Some of these also included hoax calls to fire services. Some reported actual arson performed by the caller; while others were hoax calls alleging arson. A very large source of cases were 999 calls. Some of them were to ambulance services; others to the police. Some made an accusation of murder; others alleged an assault.

There was a very unfortunate case of a gifted young man with a mental illness. In spite of the sadness of the case, it was hardly possible not to be amused, on listening to the tape in question, at the reaction of the policewoman answering a call in which the caller said that he wanted to report an assault. She naturally asked who he was alleging had assaulted him, but he replied that it had been he who had done the assaulting!

Telephone calls to individual persons threatening to harm or kill them were another common type of case. In one such case I was supplied with a tape of forty possible suspects! One had to admire the thoroughness of the policeman who had collected them.

One of my more unusual cases was one in which the police had contrived to place a microphone where it could pick up the conversations of the members of a gang of criminals who were plotting a burglary. It wasn't particularly easy, because they had London-area accents that weren't all that distinctive.

The most notorious case I was involved with was of course the famous so-called Yorkshire Ripper series of murders. The massive publicity campaign inevitably prompted a remarkably large number of sick-minded cranks to perpetrate hoax telephone calls claiming to be from that odious voice. On one occasion on a morning in September 1979, only days after another of the Ripper murders, I received a telephone call saying that there was some concern over a brief message, purporting to come from the Ripper, which sounded to those who'd heard it exactly like the original. It threatened to "strike" in Liverpool that night. This was when I still had an open mind about whether it was likely that the Geordie voice was that of the murderer. The tape was brought to me right away, and my first impression of it was that it very likely was that Geordie voice that had become so familiar.

But one can't trust first impressions, so I got down to listening to it intensively, in the end spending fully four hours on it. This was on a mere 19 words extending over only 9 seconds. It may seem incredible that one could spend so long on so little, but that is what I found could happen in an extreme case. Of course, a good deal of that time was spent in replaying the original Geordie alongside this call to the police that had been recorded in Liverpool. The fact that it was so short accounted to a good extent for its having been the most convincing imitation of the original that I ever heard, its brevity ensuring that little was given away. However, the authentic Geordie sounds were imitated well. Especially effective was the characteristic glottalisation of the central p-sound in the word "Ripper" itself. Though, as I continued to compare them, I began to realise that it was noticeably more marked than in the original. Eventually, when I came to compare the qualities of the stressed vowel of the word "disturbed" in the two recordings, it was becoming pretty clear that there was a difference, and that it was attributable to a positive Liverpudlian flavour in the one on the tape from that city. Also the quality of the /s/ that began the syllable containing that vowel was pretty different. The rhythmic and intonational features of the original were cleverly copied. But I became increasingly conscious of the more marked rhythmic regularity of the imitation. The nasality, though no doubt partly muffled out by the indifferent quality of the recording, it was becoming apparent, was of a slightly different order. The impression one gets in carrying out intensive observations in such a way is sometimes curiously like the gradual dispersal of mists! In the end I was almost feeling like kicking myself for being taken in. But that was with hindsight, and not really justified. Anyway, by teatime I had been able to ring through with complete confidence to Milgarth, the Leeds Police Headquarters, and tell them to relax. I got the impression subsequently that they'd been pretty pleased to get the message in Liverpool too. They could gladly do without the "Ripper" on their "patch".

Other cases of elimination included one on which I was able to point out to an East Yorkshire policeman that a suspect he was taking seriously was saying a local place name in a significantly different way from that to be heard on the tape they had of a presumed murderer.

I have often been asked to describe the methods I used. I played and replayed the recordings to be compared over and over again, constantly refocussing my attention, now on one feature, now on another. I should make it clear that I never employed any other procedure than minute auditory observation. I never tried to make any use of any of the instruments available in a phonetics laboratory. This was not necessarily from scepticism regarding their efficacy but simply because I never had the occasion to acquire the necessary expertise to handle them which my colleagues who specialised in such work obtained from daily operation of such equipment. In a case in which I suspected that instrumental analysis could contribute something valuable to the investigation I was only too pleased to consult such colleagues.

Neither did I ever undertake to examine any tape physically to try to establish whether it had been tampered with. Again, since I lacked the requisite skills for such an operation, I had to refer enquirers to others to have such things done. I experimented a little with a graphic equaliser, but I found it adequately useful to play the same recordings on different sets of playback equipment through different loudspeakers and through different headsets, and of course with different settings of high and low frequency cutting controls. I was able in difficult cases of audibility to make use of versions of recordings specially "cleaned up" at police technical support units.

The kinds of equipment that I found most valuable of all were endless-loop reel tape repeaters and machines with digital re-recording features. If a case was particularly difficult, I liked to use two such machines at the same time. I had available also a reel-to-reel machine specially modified for me to be able to play at normal speeds in reverse but I made little use of it largely because in those days it was such a laborious business transferring pieces of speech from it to a repeater set-up. It was, however, a very revealing device in my opinion. Listening to speech played backwards, because it's largely heard as sound-strings rather than recognisable linguistic items, frees the observer from many subconscious preconceptions, and generally sharpens the perception of sound qualities and prosodic features. One is able to notice more easily, for example, things like nasalisation of /l/ realisations. Any manufacturer who produced a machine which could be set to play back in immediate succession a few seconds of speech alternately in normal and reverse modes would in those days certainly have had an interested would-be customer in me. This is much less of a problem now with the possibilities of modern computers.

My usual procedure was to make the most detailed phonetic transcription possible, listening to four or five-second repeats, being careful not to be misled by false contexts produced by the joins. When I was discussing a case with a prospective client, I was not very optimistic when offered less than about a hundred words; and less than thirty usually prompted me to hold out very little hope of anything useful coming from examination of them. If I wished to challenge a judgement made on the basis of notably less than a hundred words or so, I was glad to be able to refer to an advisory note of guidance to police officers produced in 1981 by the Home Office Police Scientific Development Branch at Sandridge in Hertfordshire. This advised, very sensibly in my opinion, "that the text of the original recording should be at least a hundred words long." This naturally refers to its containing a hundred words of the suspect's speech. Of course, this is only to be regarded as a useful rule of thumb. Sometimes many of a hundred words can be so unclear that they're of little use. Occasionally, far fewer words can supply quite a lot of useable data. At any rate, one rarely gets so many from a 999 call recording.

I didn't keep any records of the fairly numerous occasions on which I was involved in a preliminary consultation from which nothing followed for one reason or another. I often discouraged enquirers from supplying me with recordings which I thought were certain to be too short to be usable. I only rarely attempted to examine any recording which was not in the English language, or at least in a language I knew very well. I think a linguistic phonetic analyst not operating with a language that he knows very well indeed places himself at too great a disadvantage.

I was glad to be consulted as early as possible by any solicitor who wanted me to compare eg a recording of an illegal 999 call with a recording of the voice of a client who declared that he or she was wrongfully accused of making it. In such a case it is always very convenient to be supplied with a transcript of the illegal call, which could, if one was fortunate, contain unusual local place or personal names. I usually suggested that the sample of the accused person's speech for comparison with it should contain a reading of the script of the original call. I generally pointed out that, the more realistic it could be made, the better it would be for my purposes. Ideally, an attempt to imitate the original would seem likely to highlight the differences between the two voices most effectively. Unsurprisingly, I never obtained a recording which sounded at all really spontaneous.

Sometimes it was a difficult decision just how much longer to go on working at a problem to try and get the most satisfactory possible result. I sometimes had my hand forced by the pressures of time. For some years over the period when I accepted work on such things I requested colleagues not to refer to me as available for forensic work away from my home area but I did find the occasional forensic work I undertook very stimulating.

I was always at great pains to make it as clear as possible with just what degree of confidence (often very slight!) I made suggestions, and especially to insist that there never could be anything anywhere near certainty of identification of the possessor of a voice from any recording whatsoever. Almost always the kind of comment I supplied was merely supportive to other evidence. If a case was particularly difficult or important I was very glad to exchange impressions with one or more colleagues about it.

This activity was, at times at least, quite a controversial one, which on occasion brought forth from some of my colleagues curiously emotional and, I felt, prejudiced reactions which were quite surprising and even painful to me at times. Even so, my confidence remained unshaken that it was a worthwhile activity, genuinely able to benefit both individuals and the community. I think that it would be something less than goodhearted to fail to try, if one can, to render services of a kind for which there is quite often a very keen, even urgent, desire on the part of many fellow members of one's community.

By way of a footnote I should like to mention that according to the journal American Speech issue of Winter 1990 from an article "Voice Identification in a Criminal Law Context" at pp 341-348 by Bethany Dumas it appears that in the US State of Tennessee experts are paid only if defendants are both convicted and incarcerated! Thank heavens that was never the case here!

I decided to give up such work on reaching the age of seventy in 1996.