Computational Methods for Normalizing Acoustic Vowel Data for Talker Differences

Abstract

AbstractDirect acoustic–phonetic comparison of vowels produced by different talkers can be difficult due to the effects of anatomical and physiological talker differences on first and second formant frequencies. Since the mid‐1960s, numerous computational algorithms have been proposed to normalize formant frequency measures and reduce the effects of talker‐specific variability. These algorithms vary widely in their conceptualization: some require samples of the entire vowel space (vowel extrinsic), whereas others can be conducted on a single vowel class (vowel intrinsic); some are based on a single‐scale factor to align broad classes of talkers (such as females and males), whereas others use scale factors and/or vowel space ranges for individual talkers to align their vowel systems in the same acoustic–phonetic space. In this study, an overview of the most commonly used normalization algorithms is provided and the advantages and disadvantages of each of the approaches are discussed.