An early study with synthetic speech suggested that vowel identification includes a normalization stage, such that the listener calibrates his perceptual apparatus for each talker's vowel space [Peter Ladefoged and D. E. Broadbent, J. Acoust. Soc. Am.29, 1 (1957)]. In the present study, no evidence for such a perceptual mechanism was obtained using natural speech. Each of a set of b‐vowel‐t test; words, spoken rapidly within a sentence carrier by an adult male was presented for recognition within the carrier in which It was uttered, appropriately embedded within an identical carrier produced by a second adult male with substantially different vocal tract dimensions, and excised from sentence context. The two talkers achieved the same pitch levels and speaking rate, with the result that mixed‐talker sentences were perceived as if uttered by one talker. Errors in recognition were typically found only for isolated test words. Preliminary data from a replication of this design with more widely divergent vocal tracts (i.e., adult male and nine‐year‐old male) are similar. Apparently, some factors beyond the syllable shape the acoustic specification of vowels, though not in the sense in which normalization is traditionally defined.