Factors influencing the perception of non-familiar spectrally rotated speech syllables

Abstract

The effects of acoustic features and native phonology on the naïve perception of unfamiliar spectrally-rotated speech syllables were evaluated. Spectrally-rotated syllables were created by rotating the spectrum of naturally produced Italian CV syllables around 1500 Hz resulting in changes in the energy distribution of harmonics while preserving the temporal relationships of spectral trajectories. Italian-speaking participants with no previous spectrally-rotated speech experience were asked to describe spectrally-rotated syllables phonologically by typing onomatopoetic versions of their perceptions on a computer keyboard. The results, also used to estimate the phonological similarity of the rotated sounds, showed that the identification of rotated vowels was related to their location on the F1-F2-F3 map of native (unrotated) vowels. The discriminability of rotated sounds was examined using a separate, naïve subject group using an ABX procedure. Discrimination errors were positively correlated with the estimated phonological similarity between rotated sounds. For rotated vowels, discrimination errors were also related to their Euclidean distance in F1-F2-F3 space as revealed by regression analysis. We conclude that naïve perception of unfamiliar spectrally-rotated syllables is under the influence of native phonology, and that spectrally-rotated vowels are represented by their location in the formant space. a)Also at Behavioral Neurosciences Program, McGill University, Montreal, Canada.