Perturbing postural stability affects acoustic properties but not fluency of adult speech production during face-to-face interactiona)

Physical constraints, particularly those that challenge postural stability and control, may measurably influence speech production. This experimental study investigated how increased postural stability demands affect adults' speech production during an interactive word-guessing game. A total of 118 adults (59 pairs) played a game of Taboo while standing either on a stable surface (the ground) or an unstable surface (a wobble board), with the latter increasing demands on postural stability. Participants alternated between the roles of clue-giver and guesser; analyses focused exclusively on speech produced by clue-givers, who were instructed to describe target words (e.g., coffee) while avoiding five conceptually related Taboo words (e.g., latte, drink, morning, beans, caffeine). Acoustic analyses revealed that when clue-givers described target words to guessers while standing on an unstable surface, they produced speech with higher fundamental frequency and higher amplitude envelope, compared to the stable surface. In contrast, analyses of fluency measures, which included speech rate, pause duration, pause frequency, and filler particle frequency, showed no notable differences between conditions. Perturbing postural stability thus affects the acoustics but not the fluency of speech production.