Forensic Phonetics Australia exists to raise awareness of a legal anomaly that affects the fairness of trials in our criminal courts on a weekly basis.

It’s all about covert (secret) recordings. Check the video to get a quick taster. (WARNING: Most people find it mind-boggling.) Then read on for deeper understanding.

So we need forensic phonetics, but what is it?

Phonetics is the science of speech. Most importantly, phonetics is a branch of linguistics, which is the science of language (not of particular languages, but of language in general).

Forensic phonetics started by applying the findings of phonetic science to speech used as evidence in criminal trials. Now it is a science in its own right.

How is speech used as evidence in criminal trials?

These days, most speech evidence comes from covert recordings. These are audio recordings made without the knowledge of the speaker, usually by telephone intercept or some form of ‘bugging’.

Covert recordings are lawfully obtained for many major crimes. They can provide very helpful evidence, capturing people making admissions or giving information they would not be willing to provide openly.

Sounds exciting – where’s the problem?

For covert recordings to provide valid evidence, it is essential to establish accurately who is speaking and what they are saying. It is easy to see how an error about either one could be seriously misleading to the jury.

Determining what is said and who is saying it may seem like a straightforward matter of listening to the recording. With covert recordings, however, there can be a lot more to it.

The problem is covert recordings have to be made secretly. That makes it difficult to control their recording conditions.

As a result, they are often of very poor quality, to the extent it is genuinely difficult to hear what is said. Here’s an example of a covert recording that played an important role in a real trial for a serious crime.

I think you can see how there could be potential for debate as to what is said in a recording like this.

Even in a relatively clear recording, since you can’t see the speakers, it is far harder than you might think to determine who is speaking – to a level of certainty appropriate to the high stakes of a criminal trial.

Surely that is what forensic phonetics is for?

Yes, in cases like this, phonetic science can potentially provide useful and reliable assistance in determining who is speaking and what they are saying.

The problem is the law regarding covert recordings was developed without consulting phonetic science.

Citizens are often surprised to discover that evidence about who is speaking and what they are saying in recordings like these is routinely accepted not from independent professionals, but from detectives on the prosecution team.

Less often but still frequently, an audio engineer is consulted. Audio engineering is an entirely different discipline to phonetics. Audio engineers know about sound, but typically do not undertake any of the specialised study of language and linguistics so crucial to reliable analysis of speech.

This means it is alarmingly common for speech evidence to be presented to the jury with unreliable transcripts and/or inaccurate speaker identification.

OK sounds bad – but the jury gets to listen to the audio and form their own opinion, don’t they?

Yes they do. The law puts a lot of emphasis on the fact the judge has to instruct the jury to listen carefully to the covert recording, and form their own opinion as to its content.

Unfortunately phonetic science has shown this is an unrealistic instruction. Here’s the video that explains why – it’s worth watching again.

Wow that’s amazing!

Well yes, on one level it is amazing how much a transcript can influence your perception. On another level though, it is very well known in phonetic science.

From that point of view, what’s amazing is that the law went ahead and developed its whole process for evaluating police transcripts on the basis that the defence, and ultimately the jury, could simply ‘check’ the transcript against the audio.

Where to from here?

Now you have an impression of the problem, you might like next to look at the Problem in a bit more detail. Or The Cause gives examples (some rather entertaining) to show how speech perception really works (very different from the assumptions of ‘common knowledge’ relied on by the law). With that under your belt, you’ll be ready to delve into the Case Study, which outlines in detail how an inaccurate police transcript put a man in prison for murder.

Or if you’d rather get a quick overview?

Check out some of the options in the right sidebar. You might find The Problem in a Nutshell (20 min video) a good start? Or maybe you prefer a 2-page read from The Conversation: Covert recordings as evidence in court: the return of police ‘verballing’?? Other media mentions link from the right sidebar.

Just a note

We are focused on the Australian context, but the topics have relevance in other jurisdictions as well