Kinematics of Loud, Soft, and Whispered Speech.

Introduction: We examined the effects of four types of voicing on vocal tract movements by comparing the articulatory kinematics of whispered speech to habitual, loud, and soft conditions.

Methods: Participants included 10 males and 10 females with no history of communication disorders. They read six stimulus sentences in habitual, loud, soft, and whispered conditions. An electromagnetic articulograph tracked the tongue, jaw, and lip movements. Analysis focused on the words we do from a longer sentence. Vertical tongue/jaw and horizontal lip movements were measured during the production of the retracted and rounded front and back vowels in we do.

Results: Soft speech led to smaller and slower lip movements than in the habitual condition. Displacement increased for the tongue and jaw in loud and whispered speech compared to the habitual condition. Tongue and jaw velocity increased for loud but not for whispered speech compared to the habitual condition. Utterance duration increased for loud and whispered conditions.

Discussion: The increasing tongue and jaw displacement and velocity from soft to habitual to loud speech reported here is consistent with previous accounts. Whispering was less intense than soft speech, yet it involved larger tongue and jaw movements than habitual speech, possibly reflecting a speaker's focus on greater articulatory clarity when the acoustic signal is the weakest.