The Effects of Outer Space on Vowel Space

Abstract

After returning from the Expedition 35 space mission, astronaut Chris Hadfield reported that he had learned to speak with a weightless tongue in space, and that his tongue and lips felt heavy on landing. Such comments indicate that gravity has a substantial effect on speech articulation. Previous work has investigated the effects of altered gravity in space travel on speech production [Yu & Hansen (2017) JASA 141, 1605], however the audio assessed was from the 1969 Apollo Moon landings, and thus of poor quality due to technological limitations. These technological limitations resulted in a lack of appropriate data, eg; F1 and F2 were only assessed for one vowel, with only F1 investigated for the remaining vowels. The present analysis makes use of higher quality audio from the more recent STS-134 mission in 2011, and investigates F1 and F2 of astronaut Mark Kelly before, during, and immediately after the STS-134 mission. Approximately 90 seconds of audio from each condition (1. pre-launch interview, 2. in-space interview, 3. post-landing tarmac interview) was assessed using automated alignment and formant extraction via the Dartmouth Linguistic Automation suite (DARLA). Plotted vowel spaces from each condition suggest substantial reduction of vowel spaces in both the in-space and post-landing conditions. Three way ANOVA’s comparing F1 and F2 across all conditions indicate significant differences for all high vowels, especially for F1 which corresponds to vowel height. These observations corroborate Chris Hadfield’s descriptions that altered gravity results in observable impairments to speech motor control.