The effects of divided attention on speech in Parkinson's disease (PD) have been studied for a variety of tasks in recent years. Much of the previous research studied gait patterns while participants concurrently performed another task. There have been few studies regarding the effects of divided attention on speech in individuals with PD. The ability to communicate effectively relies in part on an appropriate rate of speech, vocal intensity, and fundamental frequency control. This study included 27 participants: 8 with PD, 12 neurologically healthy older (HO) adults, and 7 healthy younger (HY) adults. Each participant was given a list of topics to speak about during the experiment. They produced monologues under three conditions: standing, walking on a treadmill, and walking over obstacles on a treadmill. Each monologue was recorded and trimmed of pauses between topics, experimenter speech, and nonspeech behaviors before analysis. Speech rate, speaking versus pausing time, overall intensity, and intensity and fundamental frequency (F0) variability were analyzed. Median, mean, maximum, and minimum F0 increased as the gait task increased in difficulty. Mean and standard deviation of intensity also increased with gait demands. All groups had increased intensity variability when walking compared to standing. Speaking versus pausing time did not differ significantly as a function of the walking task and the results varied across the groups; the same was true for speech rate. These findings reflect changes in performance during divided attention tasks, with a greater effect on HO adults and individuals with PD than their younger counterparts.



College and Department

David O. McKay School of Education; Communication Disorders



Date Submitted


Document Type





Parkinson's disease, divided attention, aging speech