Jefta Saija - Evidence for auditory temporal integration as a process of perceptual assembly and age differences in terms of speech intelligibility and phonemic restoration

Temporal integration is the perceptual process by which sensory input is segmented over time into longer events. Particularly in the auditory domain, temporal integration has traditionally been regarded as a relatively simple perceptual function that acts chiefly to bridge brief input gaps. The present study challenges that view. Participants were presented with rapid series of successive tone stimuli, in which two deviant target tones were to be identified (RSAP task). Critically, the target tone pair would form a synthetic vowel if they were to be presented simultaneously. During the task, despite that the targets were never actually simultaneous, listeners frequently reported hearing just one sound—the synthetic vowel, rather than two successive tones. This demonstrates that auditory temporal integration, like its visual counterpart, truly assembles a percept from sensory inputs across time. Also, many studies have indicated that the speed of cognitive processing decreases from adulthood to older ages. Differences between elderly and young adults in terms of gap and temporal order judgment have been linked to this age-related cognitive slowing. With this in mind, we investigated whether elderly integrate more frequently than young adults using the RSAP task. We found no such age difference. However, with a different experiment, we did find age differences in terms of speech intelligibility and phonemic restoration with sentences of different speed; elderly benefited more from slowed speech than young adults, while speeded speech had a more detrimental effect for the elderly. Our findings therefore do not support a general cognitive slowing with advancing age, but rather a task- and process dependent cognitive slowing.