Gestalt What?

William J. Campbell M.S., Audiologist

Sorry to lay this German based noun on you, but it is a particularly relevant term when discussing the process of recognizing everyday speech in the presence of background noise.  Literally gestalt means a pattern of physical, biological , or psychological phenomena so integrated as to constitute a functional unit with properties not derivable by summation of its parts.  Yes,  speech perception  in the presence of competing message is possible not only because we wear two expensive digital hearing aids in the color of our choice, but because our auditory system has the ability to process sound in  the frequency and temporal domains.  Once our ears pick up the initial sound waves either naturally or through a properly fitted hearing aid, the brain begins its magic.  Try as they may, audiologists have only a rudimentary understanding of how we derive clarity out of a mixture of individual voices and noise from every conceivable direction.  There appears to be something special in our ability to pick out familiar sounds and voices.  Four independent specific hearing abilities that seem to be necessary are: 

                        loudness-duration discrimination

                        amplitude modulation detection

                        spectral and temporal pattern discrimination

                        familiar sound recognition

People who vary in their abilities to understand speech in difficult listening conditions seem to have differences in their ability to recognize familiar sounds.  Memory retrieval,  filling in gaps, and individual attention strategies play a major role in the final outcome.    Certainly, hearing impairment can impact each of these abilities, but just as important will be one's general ability to detect subtle changes in multidimensional communication situations.  So getting back to this gestalt thing------when it comes to hearing it's not necessarily  the bits & pieces we audiologists love to talk about but the whole ball of wax that is most amazing.  Two plus two equals ????????? depending upon the person.

Journal of the Acoustical Society of America,Vol. 122, #1, July 2007,pp 418-435

Journal of the Acoustical Society of America, Vol. 123,#6, June 2008, pp 4421-4433

Journal of the Acoustical Society of America, Vol. 124, #2, August 2008, pp 1105-1115

Journal of the Acoustical Society of America, Vol. 124,#3, September 2008, pp 1668-1681