Phonetics of Polish "soft"-"hard" vowel allophony

This paper reports on the results of a three-dimensional ultrasound study of Polish vowels in consonant-vowel sequences. It was found that allophonic variation in vowels in the context of "soft" consonants is consistently implemented phonetically by means of tongue root advancement, which effectively expands the pharyngeal cavity and reduces the volume of the oral cavity. The tongue root is also consistently advanced in the soft consonants that trigger vowel allophony and retracted (or neutral) in the "hard" sounds, which do not trigger allophony, suggesting that tongue root advancement is part of the phonological representation of the "softness" (or palatalization) contrast. In parallel to this allophony, the same tongue root mechanism was found to underlie the phonotactic distribution of the phonemic vowels /i/ and /ɨ/, yielding an entirely symmetric system with consonant-vowel sequences always obligatorily compatible in terms of the position of the tongue root.