Figure 5.

Average F1-F3 acoustic space for males (4 years through adulthood) from 10 of the 21 studies listed in Appendix 1. Plotted data are averages across studies, at a given age, for the four corner vowels. Separate vowel quadrilaterals formed from these averages are shown at each age. The last column in Appendix 1 indicates the studies that had F3 data available for formant average calculations, and lists the specific ages for which data were available for averaging.