The literature on vowel perception contains contradictory claims concerning the use of information from the consonant-vowel and vowel- consonant transitions in vowel recognition. Some studies claim to have found that listeners use vowel formant track shape to compensate for changes in production brought about by coarticulation. Others claim that no evidence for such a compensation could be found. Our own experiments show that the information in the formant track shape of synthetic vowels is not always used in a way that would have benefited recognition of comparable natural vowels. A re-evaluation of the literature shows that evidence for compensatory processes, i.e. perceptual-overshoot and dynamic-specification, was only found when vowel realizations were presented in an appropriate context. Some studies show that vowel recognition deteriorates when vowel segments are presented out of context. These facts suggest that the presence of an appropriate context is essential for any perceptual compensation of coarticulatory changes.
We present a straightforward and robust algorithm for periodicity detection, working in the lag (autocorrelation) domain. When it is tested for periodic signals and for signals with additive noise or jitter, it proves to be several orders of magnitude more accurate than the methods commonly used for speech analysis. This makes our method capable of measuring harmonics-to-noise ratios in the lag domain with an accuracy and reliability much greater than that of any of the usual frequency-domain methods.