Classification of self-normalized vowels

The classical vowel measurements of Peterson and Barney in 1952 have been reexamined on an individual basis to determine the minimum dimensionality required to classify a single talker´s vowels, and the minimum number of vowels required to specify the dimensions. It was found that two formants are adequate for this purpose, and that no more than three vowels are required to scale the frequencies of two-formant space. Within that self-normalized space, all vowels have standard locations which are similar for all talkers.