RELATIONSHIPS BETWEEN INTRA-SPEAKER VARIATION IN AERODYNAMIC MEASURESOF VOICE PRODUCTION AND VARIATION IN SPL ACROSS REPEATED RECORDINGS

Intra-speaker variation in aerodynamic and acoustic measures of voice Production across repeated recordings was studied in relation to cross -recording vari ion in SPL for three normal female and three normal ma le speakers. Group data for 15 females and 15 males served as the stat istical reference. The speech material consisted of syllable strings s oft, normal, and loud voice, Measures were made of (a) parameters char acterizing the inverse filtered oral airflow waveform, (b) the inferre d average transgiottal air pressure and glottal airflow, and (c) SPL. The results showed that intra-speaker parameter variation across recor dings was generally less than 2 standard deviations relative to group mean values. In terms of relation to variation in SPL, the measures co uld be divided into two main groups: (a) For air pressure, AC flow, an d maximum flow declination rate, both intra-speaker variation across r ecordings and inter-speaker (group) variation was related systematical ly to variation of SPL. For these measures, it is suggested that varia tion across recordings was due in part to SPL differences, which can b e adjusted for statistically, thus facilitating comparisons between ab solute values. (b) For other measures, neither intra-speaker variation across recordings nor inter-speaker group variation was systematicall y related to SPL. However, some of these latter measures changed with SPL in an orderly fashion across soft, normal, and loud voice for indi vidual speakers. The results are discussed in terms of the clinical us e of these measures in studies of voice disorders.