Effects of Low-Pass Filtering on the Perception of Word-Final Plurality Markers in Children and Adults With Normal Hearing
Purpose The purpose of this study was to evaluate the effect of low-pass filtering on the detection of word-final /s/ and /z/ for children and adults with normal hearing. Method Stimuli were nouns from the University of Western Ontario Plurals Test (Glista & Scollie, 2012), low-pass filtered with 5 different cutoff frequencies: 8000 Hz, 5000 Hz, 4000 Hz, 3000 Hz, and 2000 Hz. Listeners were children (age range = 7–13 years) and adults with normal hearing. The task was a 2-alternative forced-choice task with a picture-pointing response. Results Performance was worse for lower than for higher low-pass filter cutoff frequencies, but the effect of low-pass filtering was similar for children and adults. Nearly all listeners achieved 100% correct performance when stimuli were low-pass filtered with cutoff frequencies of 8000 Hz or 5000 Hz. Performance remained well above chance even for the most severe filtering condition (2000 Hz). Restricting high-frequency audibility influenced performance for plural items to a greater extent than for singular items. Conclusion The results indicate that children and adults with normal hearing can use acoustic information below the spectral range of frication noise typically associated with /s/ and /z/ to discriminate between singular and plural forms of nouns in the context of the University of Western Ontario Plurals Test.