Academic journal article Attention, Perception and Psychophysics

Effect of Initial-Consonant Intensity on the Speed of Lexical Decisions

Academic journal article Attention, Perception and Psychophysics

Effect of Initial-Consonant Intensity on the Speed of Lexical Decisions

Article excerpt

Published online: 17 January 2014

# Psychonomic Society, Inc. 2014

Abstract In the present study, we investigated the effect of initial-consonant intensity on lexical decisions. Amplification was selectively applied to the initial consonant of monosyllabic words. In Experiment 1, young adults with normal hearing completed an auditory lexical decision task with words that either had the natural or amplified initial consonant. The results demonstrated faster reaction times for amplified words when listeners randomly heard words spoken by two unfamiliar talkers. The same pattern of results was found when comparing words in which the initial consonant was naturally higher in intensity than the low-intensity consonants, across all amplification conditions. In Experiment 2, listeners were familiarized with the talkers and tested on each talker in separate blocks, to minimize talker uncertainty. The effect of initial-consonant intensity was reversed, with faster reaction times being obtained for natural than for amplified consonants. In Experiment 3, nonlinguistic processing of the amplitude envelope was assessed using noise modulated by the word envelope. The results again demonstrated faster reaction times for natural than for amplified words. Across all experiments, the results suggest that the acoustic-phonetic structure of the word influences the speed of lexical decisions and interacts with the familiarity and predictability of the talker. In unfamiliar and less-predictable listening contexts, initial-consonant amplification increases lexical decision speed, even if sufficient audibility is available without amplification. In familiar contexts with adequate audibility, an acoustic match of the stimulus with the stored mental representation of the word is more important, possibly along with general auditory properties related to loudness perception.

Keywords Spoken word recognition . Speech perception . Audition . Temporal envelope

The neighborhood activation model has established that the speed and accuracy of word recognition is influenced by properties of the lexicon, such as the frequency of a word's occurrence in the language and the number of phonologically similar "neighbors" (Luce & Pisoni, 1998). Predictions from this model are based on the strength and number of competitors activated during the lexical search (i.e., the neighborhood). Exemplar theory suggests that the full robustness (e.g., lexical and indexical cues) of the stimulus, the spoken word in this case, is stored in memory (Goldinger, 1998). Therefore, mental representations include phonetic and supralinguistic details of specific tokens, such as indexical characteristics that could be used to identify the talker. Modifying the acoustic properties of a target word from its natural production, such as implemented during the spectral shaping of hearing aids in which some frequencies are amplified more than others, may lead to poorer success during the lexical search (i.e., slower) due to an acoustic mismatch between the stimulus and the stored representation. Such an acoustic mismatch is explicitly coded in the Ease of Language Understanding model (ELU; Rönnberg, 2003;Rönnbergetal.,2013), which predicts greater recruitment of cognitive resources for unfamiliar acoustic modifications, such as the amplitude compression of hearing aids (Foo, Rudner, Rönnberg & Lunner, 2007;Rudner,Foo, Rönnberg, & Lunner, 2009). In contrast, certain acoustic modifications, such as amplification, may improve bottomup acoustic processing of the stimulus prior to the lexical search, due to improved audibility. Amplification may increase the speed at which the stimulus is detected, giving later lexical processing a "head start." It is clear that the lexical search is highly sensitive to phonetic manipulations of the input (see Tanenhaus, Magnuson, Dahan, & Chambers, 2000). However, subphonetic acoustic interactions with the lexical search (such as those resulting from amplification) have not been fully investigated, particularly as they relate to the speed of lexical decisions. …

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