Temporal Onset Asynchrony

Temporal Onset Asynchrony

How are we able to maintain a constant perception of speech quality in the midst of daily background noise  such as unwanted speech, traffic, wind, water running, fans, to name just a few?  Most of these distractors contain frequencies similar to those found in speech .  However, their timing cues such as duration and onset/offsets  are frequently misaligned with the complex temporal information inherent in conversational speech.  It is this type of millisecond like asynchrony between speech and noise that potentiates our auditory system to group common sources  and allows for perceptual separation between speech and noise .  An interesting study in the May 2006 issue of the Journal of the Acoustic Society of America  sheds light on how our central auditory system (the brain!) might handle such tasks with vowels using neural circuitry in the form of onset asychrony and lateral inhibition at the level of the brainstem  (specifically the cochlear nucleus).   Obviously, the effects of age, hearing loss, etc…. are factors that can  reduce this ability.  Visit an audiologist with experience in such matters in the event you notice a change for the worse in quality and/or clarity of everyday speech. 

Journal of the Acoustical Society of America,                Vol.119, No.5, May 2006, pp 2905-2918

Journal of the Acoustical Society of America,Vol. 121, No.6., June 2007, pp 3655-3665; 3666-3676

Journal of the Acoustical Society of America, Vol. 124, No.1, July 2008, pp 462-471

Journal of the Acoustical Society of America, Vol. 124, No.5, November 2008, pp 3249-3260

Journal of Acoustical Society of America, Vol. 129, No. 3, March 2011, pp- 1490-1508