Forensic study of a case involving SMS text-to-speech conversion

Abstract

The process of decoding the content of a message involving Short Message-to-speech conversion is described in the form of a forensic case study. The intelligibility of the message was low, primarily due to the fact that the written input to the text-to-speech system was inTurkish although the system was designed for text-to-speech conversion in German. This created some form of synthesised Turkish with a German “accent”. It is shown how “spectrogram reading” can be employed in the task of deriving phonetic categories from the signal of the synthetic speech message. In order to obtain a maximally accurate estimate of the input typed by the sender, one disputed passage of the SMS-to-speech message was subjected to a simulation. It is described how a full match between the case material and the simulated passage was obtained, despite typographical errors and incorrect Turkish orthography on the part of the sender.