Five experiments explored the effect of acoustic changes between study and test on implicit and explicit memory for spoken words. Study-test changes in the speaker's voice, intonation, and fundamental frequency produced significant impairments of auditory priming on implicit tests of auditory identification and stem completion but had little or no effect on explicit recall and recognition tests (Experiments 1-4). However, study-test changes in overall decibel level had no effect on priming on an auditory stem-completion test or on cued-recall performance (Experiment 5). The results are consistent with the idea that fundamental frequency information is represented in a perceptual representation system that plays an important role in auditory priming.