The effect of interval order and highpass filtering on the pitch strength of shuffled click-train regular interval stimuli

Abstract

Regular interval stimuli (RIS) contain temporal regularities that are known to produce a pitch percept. Previous experiments [Mapes-Riordan and Yost, ARO MidWinter meeting proceedings (2000)] showed that shuffled, wide-band first-order ‘‘kxkx’’ click-train RIS have a stronger pitch strength than the original, unshuffled stimuli, where ‘‘k’’ is a fixed duration interval and ‘‘x’’ is a random interval. The primary difference between ordered and shuffled click-train sequences is that shuffled sequences contain multiple instances of regular ‘‘k’’ intervals. This result provides evidence for the importance of the short-term periodicity within RIS in determining its pitch strength. The current experiments investigated whether this phenomenon also occurred when the RIS were created from higher-order intervals and/or whose spectrum was limited to unresolved frequency channels. A set of trials was run in which listeners compared the pitch strength of an ordered click-train RIS and a shuffled version of the same sequence. Relative pitch strength judgments were made as a function of the regular interval duration, regular interval order, and highpass filter cutoff frequency. The results of these experiments revealed that second-order interval click-train RIS require resolved frequency components to generate a salient pitch percept. [Work supported by a NIDCD Program Project Grant.]