Rate-dependent perception of quantity in released and unreleased syllables in Icelandic
Previous research (Find, 1986, 1995a) has shown that the ratio of vowel to rhyme (vowel + consonant) duration is a major cue for quantity in Icelandic and serves as a higher-order invariant which enables the listener to disentangle those durational transformations of the speech signal which are due to changes in the speaking rate from those which involve a change of phonemic quantity. For the listener to be able to calculate this ratio, both segments, vowel and consonant, need to be present in the acoustic waveform. This paper reports two perceptual experiments using edited natural speech where a closure following the vowel is either audible or not (in the latter case the closure is unreleased). Results support the hypothesis that the surrounding context will have a greater effect on the location of the phoneme boundaries for vowel quantity in the unreleased syllables since in that case the listener will not be able to calculate the vowel to rhyme ratio.
quantity icelandic higher-order invariants speaking rate speech perception