Subglottal resonances in older adults

Absztrakt

The subglottal acoustic input impedance partially consists of a series of resonances that are acoustically excited during voiced speech. Measurement of these subglottal resonances (SGRs) has thus far been restricted almost entirely to young adults and children. However, many aspects of the speech production system are known to change as adults age, and there is a possibility that SGR measurements might have clinical value in older adults. This study examined SGRs measured in 10 adults (5 males, 5 females) aged 50-80 years, and probed the dependence of SGR frequencies on vowel quality, posture, pulmonary function, as well as standing height, sitting height, weight, and age. Previously reported data from young adults were also compared with the new data from older adults. Vowel quality affected the frequency of the first subglottal resonance (Sg1) (Sg1 was higher in [a:] than [i:] or [u:]), and age (older adult vs. younger adult) affected the frequencies of the first and second subglottal resonance (Sg1, Sg2) (both SGRs were lower in older adults). Posture did not affect SGR frequencies, and no other significant relationships were found. The interaction of vowel quality with Sg1 is likely due to acoustic coupling between the subglottal and supraglottal (vocal tract) airways during phonation. The interaction between Sg1 and vowel quality was previously reported to be non-significant in younger adults, and the significant interaction in older adults could be due to age-related changes in laryngeal biomechanics and motor control. Based on previous modeling work, the interaction of age with both Sg1 and Sg2 is most likely due to age-related changes in the geometry and biomechanics of the subglottal airways, but empirical verification of this hypothesis is still needed.