The relative roles of vowels and consonants in discriminating talker identity versus word meaning.

Three experiments tested the hypothesis that vowels play a disproportionate role in hearing talker identity, while consonants are more important in perceiving word meaning. In each study, listeners heard 128 stimuli consisting of two different words. Stimuli were balanced for same/different meaning, same/different talker, and male/female talker. The first word in each was intact, while the second was either intact (Experiment 1), or had vowels ("Consonants-Only") or consonants wels-Only") replaced by silence (Experiments 2, 3). Different listeners performed a same/ different judgment of either talker identity (Talker) or word meaning (Meaning). Baseline testing in Experiment 1 showed above-chance performance in both, with greater accuracy for Meaning. In Experiment 2, Talker identity was more accurately judged from Vowels-Only stimuli, with modestly better overall Meaning performance with Consonants-Only stimuli. However, performance with vowel-initial Vowels-Only stimuli in particular was most accurate of all. Editing Vowels-Only stimuli further in Experiment 3 had no effect on Talker discrimination, while dramatically reducing accuracy in the Meaning condition, including both vowel-initial and consonant-initial Vowels-Only stimuli. Overall, results confirmed a priori predictions, but are largely inconsistent with recent tests of vowels and consonants in sentence comprehension. These discrepancies and possible implications for the evolutionary origins of speech are discussed.