GROUP-DIFFERENCES IN MEASURES OF VOICE PRODUCTION AND REVISED VALUES OF MAXIMUM AIR-FLOW DECLINATION RATE

In previous reports, aerodynamic and acoustic measures of voice produc tion were presented for groups of normal male and female speakers [Hol mberg et al., J. Acoust. Soc. Am. 84, 511-529 (1988); J. Voice 3, 294- 305 (1989)] that were used as norms in studies of voice disorders [Hil lman et al., J. Speech Hear, Res. 32, 373-392 (1989); J. Voice 4, 52-6 3 (1990)]. Several of the measures were extracted from glottal airflow waveforms that were derived by inverse filtering a high-time-resoluti on oral airflow signal. Recently, the methods have been updated and a new study of additional subjects has been conducted. This report prese nts previous (1988) and current (1993) group mean values of sound pres sure level, fundamental frequency, maximum airflow declination rate, a c flow, peak flow, minimum flow, ac-dc ratio, inferred subglottal air pressure, average flow, and glottal resistance. Statistical tests indi cate overall group differences and differences for values of several i ndividual parameters between the 1988 and 1993 studies. Some inter-stu dy differences in parameter values may be due to sampling effects and minor methodological differences; however, a comparative test of 1988 and 1993 inverse filtering algorithms shows that some lower 1988 value s of maximum flow declination rate were due at least in part to excess ive low-pass filtering in the 1988 algorithm. The observed differences should have had a negligible influence on the conclusions of our stud ies of voice disorders.