Consistency of Order Effects in Higher Effort Speaking Styles Between Sessions.

Purpose: The purpose of this investigation was to determine the extent to which instruction order impacts the clear and loud speech response and to examine the consistency of the clear and loud speech response across two sessions.

Method: Acoustic and kinematic data from sentences produced in habitual, loud, and clear speech styles were collected from participants assigned in two groups: a Clear-Loud group (order: habitual, clear, loud) and a Loud-Clear group (order: habitual, loud, clear styles). Participants performed the same protocol order during two sessions scheduled 1 week apart.

Results: Analyses revealed that there were no significant differences between groups for speech intensity, lip aperture range, and speech rate in the habitual style. In both sessions, talkers in the Clear-Loud group exhibited a modest increase in speech intensity between the habitual and clear style and a larger increase between the clear and loud style. Alternatively, talkers in the Loud-Clear group exhibited no differences in speech intensity between the loud and clear styles, retaining the increases associated with the loud style during clear speech. Additionally, talkers in the Loud-Clear group exhibited a more graded change in lip aperture range and speech rate between the habitual, loud, and clear speech styles. In contrast, those in the Clear-Loud group retained the changes in lip aperture range and speech rate that were observed in the clear style when performing the loud style.

Conclusion: Despite some between-participant variation in the observed trends, these data suggest that most talkers retained characteristics of the previously performed higher effort style in subsequent style.