Effects of talker, rate, and amplitude variation on recognition memory for spoken words

Abstract

This study investigated the encoding of the surface form of spoken words using a continuous recognition memory task. The purpose was to compare and contrast three sources of stimulus variability-talker, speaking rate, and overall amplitude-to determine the extent to which each source of variability is retained in episodic memory. In Experiment 1, listeners judged whether each word in a list of spoken words was "old" (had occurred previously in the list) or "new." Listeners were more accurate at recognizing a word as old if it was repeated by the same talker and at the same speaking rate; however, there was no recognition advantage for words repeated at the same overall amplitude. In Experiment 2, listeners were first asked to judge whether each word was old or new, as before, and then they had to explicitly judge whether it was repeated by the same talker, at the same rate, or at the same amplitude. On the first task, listeners again showed an advantage in recognition memory for words repeated by the same talker and at same speaking rate, but no advantage occurred for the amplitude condition. However, in all three conditions, listeners were able to explicitly detect whether an old word was repeated by the same talker, at the same rate, or at the same amplitude. These data suggest that although information about all three properties of spoken words is encoded and retained in memory, each source of stimulus variation differs in the extent to which it affects episodic memory for spoken words.A long-standing problem for theories of speech perception and spoken word recognition has been perceptual constancy in the face of a highly variable speech signal. Listeners extract stable linguistic percepts from an acoustic speech signal that varies substantially due to idiosyncratic differences in the size and shape of individual talkers' vocal tracts as well as to differences within and among talkers in factors such as speaking rate, dialect, speaking style, and vocal effort. Traditionally, researchers have adopted an abstractionist approach to the problem of perceptual constancy, assuming that variability in the speech signal is perceptual "noise" that must be "stripped away" during perception to arrive at a series of abstract, canonical linguistic units (see Pisoni, 1997). Research has typically focused either on searching for sets of acoustic, articulatory, or relational invariants hypothesized to allow access to phoneme-and ultimately word-sized units (e.g., Kewley-Port, 1983;Stevens & Blumstein, 1978) or on normalization algorithms and processes that would successfully filter out stimulus variation to arrive at the abstract units thought to underlie further

Examining the Time Course of Indexical Specificity Effects in Spoken Word Recognition.

“…Unlike Schacter and Church, Goldinger presented words in noise at both study and test, which may be responsible for the differences across the two sets of studies (see Franks, Bilbrey, Lien, & McNamara, 2000). A number of other studies have also obtained specificity effects, providing additional evidence that indexical information is stored in memory and has consequences for subsequent perceptual processing (see, e.g., Bradlow, Nygaard, & Pisoni, 1999;Fuji moto, 2003;Houston & Jusczyk, 2003 [in infants]; Yonan & Sommers, 2000 [in elderly adults]). These findings demonstrate that indexical information, particularly talker identity, is retained in memory and has a number of consequences for subsequent processing, contrary to the speaker normalization hypothesis.…”

How robust are exemplar effects in word comprehension?

“…Exemplar effects have been established in several priming experiments (e.g., Bradlow, Nygaard, and Pisoni, 1999;Craik and Kirsner, 1974;Goh, 2005;Goldinger, 1996;Janse, 2008;Mattys and Liss, 2008;McLennan et al, 2003;McLennan and Luce, 2005;Palmeri, Goldinger, and Pisoni, 1993).…”

“…Many articles in the literature point to a role of exemplars in word comprehension. This study investigates the robustness of these exemplar effects.Exemplar effects have been established in several priming experiments (e.g., Bradlow, Nygaard, and Pisoni, 1999;Craik and Kirsner, 1974;Goh, 2005;Goldinger, 1996;Janse, 2008;Mattys and Liss, 2008;McLennan et al, 2003;McLennan and Luce, 2005;Palmeri, Goldinger, and Pisoni, 1993).These experiments contained repeated words and the comprehension of the second occurrence of a word (the target) is expected to be facilitated by the first occurrence (the prime). Primes and targets were completely identical, that is the same token, or they differed in speech rate, time-compression, the realization of a certain segment (e.g., intervocalic /t,d/ produced as [t,d] or as a flap in American English), or the speaker's voice.…”

“…For instance, in Bradlow et al (1999), speech rate, amplitude, and speaker were varied, but each participant only heard one of these variations. In Experiments 3 and 4, we investigated whether exemplar effects also arise if the stimuli in the experiment differ in two indexical properties: degree of reduction and speaker voice.…”

A new method for eliciting three speaking styles in the laboratory

“…The perception of variability that exists among speech styles has not been studied in detail, no doubt due to the problem of eliciting naturalistic speech in the decidedly unnatural manner and the setting of reading aloud in a laboratory, although these issues have begun to be addressed in computer/machine word recognition (Ostendorf, Byrne, Bacchiani, Finke, Gunawardana, Ross, Roweis, Shriberg, Talkin, Waibel, Wheatley, & Zeppenfeld, 1996;Schriberg, 2001;Liu, Shriberg, Stolcke, Hillard, Ostendorf, & Harper, 2006;Bates, Ostendorf, & Wright, 2007). Other types of "nonlinguistic" variability have been shown to have an effect on speech perception and spoken word recognition, including talker, rate, and stimulus variability (Mullennix & Pisoni, 1990;Nygaard, Sommers, & Pisoni, 1995;Bradlow, Nygaard, & Pisoni, 1999). These studies suggest that listeners encode in longterm memory significant episodic details and properties of speech signals that they encounter, and that these details influence the subsequent perception and recognition of speech.…”