Monday, December 19, 2005

Maybe Forensic Audio Examiners and Transcribers Should Switch Ears?

A few days ago, I came across a newspaper article that referred to the decoding preferences of the left and right ears in humans. As usual, I lost the link and had to go hunting for it again. Although I didn't find the exact same link, I did find a different write-up that was likely about the same study. This write-up states that both adults and newborns have an inborn preference for decoding speech with the left side of the brain and tones with the right. Because of the way that the brain is 'cross-wired', this means that we are slightly better at hearing speech with the right ear and tones & music with the left.

This seems to agree with my anecdotal observations of people leaning in with their right ears to listen to other people talking in loud noise environments. The left ear is then turned away (toward the directional or diffuse noise and in the acoustic shadow of the head from the direction of the desired talker) thus giving the best noise 'reference' possible for the brain to 'filter' with.

As all professional forensic audio filters (processors) default to the left channel for the primary signal (i.e. the noisy speech input AND the filtered speech output) and to the right channel for the noise reference (i.e. music, resonance, etc.), on the basis of this report, it seems to make sense to listen to marginal recordings the opposite way around from now on (i.e. swap the left and right channels). I'll experiment myself by trying it both ways. If there are are any obvious differences, I'll report back.

(Note: Edited after the initial posting to correct some errors I caught.)

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