0185 SPEECH AS A RELIABLE MARKER OF ALERTNESS AND PERFORMANCE IMPAIRMENT UNDER CONDITIONS OF ACUTE SLEEP DEPRIVATION

Abstract

The acoustic properties of speech are a reliable marker of changes in the central nervous system. Measures of speech timing and frequency have been used to assess impairment in clinical patient groups, including stroke, Huntington’s disease, and depression. Associations between speech properties and impaired performance have also been described in healthy individuals under periods of sleep deprivation. In the current study, we aimed to compare the time course of speech outcomes to other objective measures of alertness during 40 hours of sleep deprivation. Methods Twenty-three healthy volunteers (18 males; mean age=25.41 ± 5.73 years) underwent 40 hours of acute sleep deprivation under constant routine conditions. Speech tasks were administered every four hours, beginning three hours after scheduled waketime. The Psychomotor Vigilance Test (PVT), Karolinska Sleepiness Scale (KSS), and EEG collected during the Karolinksa Drowsiness Test (KDT) were measured bi-hourly. Objective measures of speech were derived using spectral, cepstral and timing analyses. Results Acoustic parameters displayed impairment across 40-h of sustained wakefulness. Measures of speech timing (e.g. speech rate) and frequency deteriorated significantly following 23 hours awake compared to baseline (first 16 hours awake). Impairment peaked around 31 hours of wakefulness before showing slight improvements. These findings were consistent with laboratory standard assessments of sleepiness and vigilant attention. Conclusion The time course of changes in the acoustic properties of speech are comparable to those changes observed in alertness and performance impairment across 40 h of sleep deprivation. These findings suggest the acoustic properties of speech may be a reliable indicator of alertness/drowsiness, with utility for development of objective and non-invasive systems to identify and manage sleep-related impairment in workplace settings. Support (If Any) The study was supported by the Cooperative Research Centre for Alertness, Safety and Productivity.