Impact of familiar, unfamiliar, and synthetic voices on the arousal and awareness of minimally-conscious survivors of acquired brain injury
Survivors of acquired brain injury (ABI) often experience a period of impaired consciousness following injury. This period may be brief or may last hours, days, weeks, or months. While in states of impaired consciousness, survivors demonstrate fluctuations in arousal and awareness levels in accordance with variations in environmental stimulation. In general, routine stimulation provided in hospital settings is not intense, frequent, or persistent enough to maintain arousal and environmental awareness in ABI survivors with impaired levels of consciousness. Consequently, health care professionals implement sensory stimulation programs to prevent sensory deprivation and help survivors re-establish normal arousal and awareness levels.
This study's purposes were to determine whether three ABI survivors with impaired consciousness (a) demonstrated changes in responsiveness when purposefully presented with auditory stimuli rather than only hearing stimuli occurring naturally in the environment and (b) responded differentially to auditory stimulation presented with familiar, unfamiliar, or synthetic voices. Each survivor participated in two auditory stimulation sessions daily for 30 days. The video recorded sessions included two minutes of baseline, four minutes of stimulation involving presentation of one of the three types of auditory stimuli, and two minutes of post-stimulation. Subsequent analysis of the recordings allowed for determination of changes in a survivor's production of reflexive and purposeful movements before, during, and after stimulus presentation.
Three major conclusions resulted from the study. First, two survivor participants demonstrated a change in level of responsiveness with presentation of the sensory stimulation. This suggests that auditory stimulation results in changes in level of arousal for some ABI survivors. Second, none of the participants demonstrated a differential response to the three types of voices used as experimental stimuli. This suggests that voice familiarity may not be an important factor when selecting auditory stimuli. Third, each survivor demonstrated a unique response profile. This reinforces the importance of using both quantitative and qualitative descriptions when describing individuals with impaired consciousness.