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Effects of auditory signal degradation on speech-motor synchronization and audiovisual integration abilities
Poster Session B, Wednesday, September 30, 4:30 - 6:30 pm, Wangari Maathai
This poster is part of the Sandbox Series.
Susanna Girino1,2,3, Raffael Schmitt4,5,6, Defne Abur2,3, Nathalie Giroud4,5,6,7; 1University Medical Center Groningen, University of Groningen, 2University of Groningen, 3Research School of Behavioral and Cognitive Neurosciences, University of Groningen, 4University Hospital of Psychiatry, University of Zurich, 5International Max Planck Research School on the Life Course: Evolutionary and Ontogenetic Dynamics (LIFE), 6University of Zurich, 7ETH Zurich
Spontaneous synchronization of speech (SSS) is the ability to align one's speech-motor production with external information without explicit training and reflects vocal learning. SSS relies on multimodal integration of internal and external sensory information with prior knowledge to maintain effective communication. The ability to integrate this sensory information depends on the reliability of the perceptual cue. Clear and consistent perceptual information (e.g., sharp visual stimuli or rhythmic auditory cues), is highly reliable and easy to integrate, whereas degraded perceptual signals (e.g., noisy) are less reliable and more difficult to integrate. The relative reliance on internal versus external information varies across individuals and is further modulated by contextual factors (e.g. adverse listening situations). In the present study, age-related hearing impairment and background noise were investigated as sources of internal and external signal degradation, respectively. The overarching aim was to determine the effects of internal and external signal degradation on SSS and audiovisual integration in older adults with hearing impairment. The study included twenty-five older adults (mean age: 73.6 years; range: 67–80 years; 11 females, 14 males). Participants were native Swiss-German speakers with varying degrees of hearing impairment (mild to mild-to-moderate), as measured by pure-tone average in decibel hearing level (dB HL) (mean: 31.1 dB HL, range: 6–51.6 dB HL). Participants reported normal vision, no neurological or psychiatric disorders, and no speech or language deficit. To test speech-motor synchronization, an SSS syllable production task was used. Rhythmic trains of 4.5 syllables per second were played to participants, who were asked to whisper the syllable ‘tah’ simultaneously. Each trial, participants were asked to recall which syllables had been presented. There was no explicit instruction to synchronize their production rate with the presented stimuli. Phase-locking values for 4.5 Hz syllable rate envelopes will be computed to examine the degree of synchronization between a speaker’s own rate and the stimuli. To test audiovisual integration, a sentence comprehension task was used. Participants were presented with sentence audiovisual recordings and required to judge whether a target word had been pronounced, based on auditory information, the speaker’s mouth movements, or both. Five conditions were presented in a randomized order: auditory-only no noise, auditory-only noise, audiovisual no noise, audiovisual noise, and visual-only. As measures of audiovisual integration, response accuracy and reaction times in milliseconds will be analysed. Participants are expected to cluster into high- and low-synchronizers, independently of hearing impairment. High-, compared to low-synchronizers, are hypothesized to perform better at audiovisual integration, even when perceptual information may be unreliable (i.e., noisy). The results will clarify how unreliable internal and external perceptual information influences sensory integration during speech, which is relevant for characterizing typical and disrupted speech control. Data has been collected and analysis is ongoing; results will be presented and discussed at the conference. The sandbox series will support discussion about the analyses, including possible mechanisms that may drive high and low synchronization.
Topic Areas: Speech Motor Control, Multisensory or Sensorimotor Integration