'Enhancing' forensic audio: what if all that really gets enhanced is the credibility of a misleading transcript?

Abstract

Many jurisdictions around the world allow an 'enhanced' version of indistinct audio to be admitted, along with a transcript, to assist the trier of fact in understanding the content of forensic recordings. Typically, ultimate evaluation of the effect of the 'enhancing' relies simply on the jury or other listeners' impression as to whether the audio sounds 'clearer' than the original. A recent article reported results of two experiments showing that listeners' subjective impressions give a surprisingly unreliable indication of the objective effects of 'enhancing'. The current article reports a new experiment that adds weight and detail to previous demonstrations that enhancing can make audio 'sound clearer' without making it more reliably intelligible. It further demonstrates how 'enhancing' can interact with priming to make phrases suggested by a transcript seem more plausible than they do in the original, even when the suggestion is unreliable and misleading. It is recommended that courts should insist on far better regulation of the use of 'enhanced' audio.