Contributions of surface and conceptual information to recognition memory.

The present experiments were designed to determine whether memory for the voice in which a word is spoken is retained in a memory system that is separate from episodic memory or, instead, whether episodic memory represents both word and voice information. These two positions were evaluated by assessing the effects of study-to-test changes in voice on recognition memory after a variety of encoding tasks that varied in processing requirements. In three experiments, the subjects studied a list of words produced by six voices. The voice in which the word was spoken during a subsequent explicit recognition test was either the same as or different from the voice used in the study phase. The results showed that word recognition was affected by changes in voice after each encoding condition and that the magnitude of the voice effect was unaffected by the type of encoding task. The results suggest that spoken words are represented in long-term memory as episodic traces that contain talker-specific perceptual information.

Voice-specificity effects on auditory word priming.

This research explores the nature of the memory traces that support spoken word identification. Specifically, do voice-specificity effects in implicit memory depend on information in a perceptual representational system or, alternatively, on the similarity of study and test exemplars? Memory for words and voices was assessed with two perceptual identification tests--the identification of words in noise and the identification of low-pass filtered words--after two encoding conditions (identification of words in noise and of words in the clear). At test, a word was presented in the same voice as at study or in a different voice. The data from the two experiments showed that study-to-test changes in voice reduced priming and that voice-specificity effects were greatest when the type of processing engaged at study overlapped with that required at test. Taken together, the results implicate the goodness of the processing match between encoding and test as the primary determinant of voice-specificity effects on perceptual identification tests and support the hypothesis that both voice and word information is represented within a single episodic memory system.

The effects of breath sounds on the perception of synthetic speech.

When preparing to speak, talkers typically take a breath. The perceptual effect of adding naturally produced breath intake sounds to synthetic speech was examined. In experiment 1, subjects were better at transcribing synthesized sentences that were preceded by a breath sound than those that were not, in addition to the improvement due to practice that is typically found with synthetic speech. Experiment 2 found that replacing the breath with the spectrally similar sound of rustling leaves had no effect on the accuracy. Experiment 3 had breaths before randomly selected sentences. Only the practice effect was significant, though there was a tendency for sentences with the breath sounds to be remembered better. In experiment 4, we tested whether the appropriateness of the breath sound to the sentence size (relatively short or long) affected the use of the breath sound. Appropriateness had no effect, perhaps because the range of sentence durations was too small. Experiment 5 replicated experiment 1 but used leaf sounds rather than silence in the nonbreath sentences. The presence of breath was again found to aid recall. Overall, the current results indicate that adding the breath intake sound to synthetic sentences improves listeners' ability to recall those sentences.