Respiratory and laryngeal movements associated with stutterers' delayed acoustic LRT

Abstract

Most experiments assessing laryngeal reactinn time (LRT) report that stutterers, as a group, are significantly slower in initiating phonation than nonstutterers. We have extended these studies by assessing the effects of a variable foreperiod and stuttering severity on acoustic LRT. Sufficiently long foreperiods, the time between the warning cue and phonate cue, provide subjects time to prepare for a known response. We found that mild stutterers' LRT values approached nonstutterers as foreperiod increased while severe stutterers' LRT values remained significantly longer than nonstutterers throughout the range of foreperiods. These data suggest that differential deficits (i.e.,: respiratory and laryngeal prephonatory posturing and/or vibration initiation) may underly stutterers delayed acoustic LRT values. However, acoustic measures alone are insufficient for a detailed analysis of the deficits contributing to stutterers prolonged LRT values. Therefore, we have begun investigating respiratory and laryngeal movements occurring immediately before phonation onset. Results of preliminary simultaneous acoustic and movement LRT measures will be discussed in terms of the differential deficit hypothesis. [Supported by NINCDS grant NS13870 to Haskins Laboratories.]