Breathing and Speech Adaptation: Do Speakers Adapt Toward a Confederate Talking Under Physical Effort?

Purpose: This study investigated whether speakers adapt their breathing and speech (fundamental frequency [f_o]) to a prerecorded confederate who is sitting or moving under different levels of physical effort and who is either speaking or not. Following Paccalin and Jeannerod (2000), we would expect breathing rate to change in the direction of the confederate's, even if the participant is physically inactive. This might in turn affect their speech acoustics.

Method: We recorded the speech and respiration of 22 native German speakers. They produced solo and synchronous read speech in interaction with a confederate who appeared on a prerecorded video. There were three within-subject experimental conditions: the confederate (a) sitting, (b) biking with light effort, or (c) biking with heavier effort.

Results: During speech, the confederate's inhalation amplitude and f_o increased with physical effort, as expected. Her breath cycle duration changed differently, probably because of read speech constraints. Overall, the only adaptation the participants showed was higher f_o with increase in the confederate's physical effort during synchronous, but not solo, speech. Additionally, they produced shallower inhalations when observing the confederate biking in silence, as compared to the condition without movement. Crucially, the participants' acoustic and breathing data showed large interindividual variability.

Conclusions: Our findings indicate that, in this paradigm, convergence only took place on f_o during synchronous speech and that this phonetic adaptation happened independently from any speech breathing adaptation. It also suggests that participants may adapt their quiet breathing while watching a person performing physical exercise but that the mechanism is more complex than that explained previously.