The aging of the vocal cords as well as changes in the vocal tract and in articulatory movements are responsible for the unique characteristics of speech of aged persons. In order to carry out a detailed investigation of articulation in aged persons, acoustic, optic, and aerodynamic analyses were performed on running speech samples from both young and aged persons.
The VCV syllable [aka] was extracted from a sample of Japanese speech [yabunonakakara usagiga pyokonto detekimashita] and subjected to acoustic analysis. The results for 40 aged persons were compared to those obtained for 20 young persons. In aged persons, the power of the leading vowel [a] significantly influenced and relatively weakened the plosive [k] that followed.
Fiberoptic examination of laryngeal movement during the articulation of the plosive [k] showed poor glottal opening in the aged group.
The intrapharyngeal pressures were also measured at the same time point in ten aged persons and compared with those obtained from ten young persons. The mean intrapharyngeal pressure in the aged group was significantly lower.
The results indicate that aging affects the mobility of the tongue, pharyngeal wall and soft palate, causing low intrapharyngeal pressure and poor glottal opening. As a result, the speech of aged persons tends to be less clear.