By Isabel Pancake
Four years after the disappearance of the then 15-year-old Rebecca Reusch, the police suddenly carried out acoustic measurements in the house of her sister and brother-in-law in mid-April. BZ spoke to a forensic phonetician involved.
The specialists of the Berlin police primarily analyze audio recordings and compare them with each other. This allows them to find out, for example, whether the same person was involved in several crimes.
But there is much more: the perpetrator reveals many details about himself through his voice and language! “Among other things, the regional origin can be determined from the voice through accents and dialects,” says the forensic phonetician Dr. Miriam Rolfes (49) from the LKA Berlin.
On February 18, 2019, the then 15-year-old Rebecca Reusch disappeared from Rudow – since then there has been no sign of life from her Photo: dpa
The experts from the police can also hear the age! “However, the voice does not change from year to year, but at longer intervals. This changes the voice quality, the clarity of the voice, the pitch. But formulations and the use of certain terms also indicate age,” says Rolfes.
Even the culprit’s teeth can sometimes be a tell-tale! “Tooth misalignment can be recognized by conspicuous hissing noises when speaking,” says Rolfes.
And: Not only the voice itself, but also background noise can contribute to the investigation. If a radio is playing quietly in the background, the police can use the song sequence to find out the date and the station – and thus roughly the region.
In April, the forensic phoneticians of the LKA Berlin carried out acoustic measurements in Rebecca’s brother-in-law’s house Photo: Til Biermann
By the way: disguising the voice is useless! This is because you only change a few features of the voice – never all of them. “So there’s still enough left over to recognize the person,” says Rolfes.
The skills of the forensic phoneticians are particularly useful when investigating fraud. The officials recognize, for example, whether a grandson trick caller was the perpetrator in several cases.
dr Miriam Rolfes (49) from the LKA Berlin works as a forensic phonetician and evaluates audio recordings on the computer every day Photo: Christian Lohse
Sometimes the job is particularly difficult for Rolfes. Because it also has to evaluate voices in child pornographic content. An off-screen voice can reveal something about the perpetrator. At the same time, the abuse victims can be located with the help of the forensic phoneticians so that they can get help quickly.
Recently, Rolfes and her team have also investigated a prominent case – the missing person case of Rebecca Reusch (disappeared from Rudow in 2019).
Rolfes: “But this is an ongoing process and I am not allowed to comment further.”