Cognitive processes underlying spoken word recognition during soft speech

In two eye-tracking experiments using the Visual World Paradigm, we examined how listeners recognize words when faced with speech at lower intensities (40, 50, and 65 dBA). After hearing the target word, participants (n = 32) clicked the corresponding picture from a display of four images - a target (e.g., money), a cohort competitor (e.g., mother), a rhyme competitor (e.g., honey) and an unrelated item (e.g., whistle) - while their eye-movements were tracked. For slightly soft speech (50 dBA), listeners demonstrated an increase in cohort activation, whereas for rhyme competitors, activation started later and was sustained longer in processing. For very soft speech (40 dBA), listeners waited until later in processing to activate potential words, as illustrated by a decrease in activation for cohorts, and an increase in activation for rhymes. Further, the extent to which words were considered depended on word length (mono- vs. bi-syllabic words), and speech-extrinsic factors such as the surrounding listening environment. These results advance current theories of spoken word recognition by considering a range of speech levels more typical of everyday listening environments. From an applied perspective, these results motivate models of how individuals who are hard of hearing approach the task of recognizing spoken words.