Vowel constancy: normalization
B. S. Rosner, J. B. Pickering · Oxford University Press eBooks · 1994
Variations in vocal tract size and shape cause spectral differences in the same vowel produced by different speakers. The ERB transform partly supplies the speaker normalization needed for vowel constancy. The timbre of a voice, fundamental frequency (F0), and experience with a given speaker facilitate the normalization process.