Lip rounding and dorsum backing both lower F2, and tend to co-occur in speech sounds (e.g. back vowels). This likely reflects contrast enhancement: the co-occurrence of rounding and backing exaggerates F2 differences associated with phonemic contrasts. We investigate this correlation with an articulatory study of Irish, a language with contrastively palatalized and velarized consonants. We confirm that velarized consonants are realized with additional lip rounding. However, we find no token-wise correlation between the amount of rounding and dorsum backing. This suggests that rounding is primarily associated with dorsum backing at an abstract phonemic level, not surface phonetics.
Coronals show weaker velarization in Irish, and likely recruit cues beyond F2 (e.g. spectral center of gravity) to signal /Cʲ Cˠ/ contrasts. Speakers in our study show no correlation between the degree of velarization on coronal /Cˠ/ and center of gravity separation for coronal /Cʲ Cˠ/, suggesting that speakers may not compensate for weak velarization with other phonetic cues.