Physical task stress is known to affect the fundamental frequency of speech. This study of two American English vowels /IY/ and /AH/ investigates whether physical task stress affects the center frequencies of formants F1 and F2, and whether it affects the glottal open quotient, and whether these effects are different for different speakers, the different vowels, and two different vowel contexts. Formant center frequencies are measured from the acoustic waveform, and the glottal open quotient is measured from the electroglottograph signal. The study finds in general that the production of vowels is affected by physical task stress. In particular, the study finds that F1, F2, and the glottal open quotient are affected by physical task stress. It also finds that the effects of stress on F1 vary for different speakers, and that the effects of stress on the glottal open quotient vary for different combinations of speaker and vowel.
Bibliographic reference. Godin, Keith W. / Hansen, John H. L. (2011): "Vowel context and speaker interactions influencing glottal open quotient and formant frequency shifts in physical task stress", In INTERSPEECH-2011, 2945-2948.