British English [kw], [k], and [w] distinction in back round vowel contexts

Corpus data from the Audio British National Corpus was used to compare the acoustics of British English stops with velar and/or labial articulation in onset positions preceding back rounded vowels. The acoustics of labialized velar stops in British English have not commonly been described due to their frequent phonological analysis as clusters. Labialized velars have been characterized cross-linguistically in terms of low second formant frequency, but it was found that third formant frequency is a more significant cue to differentiation in back rounded vowel contexts. Plain velars with non-phonemic labialization resulting from proximity to a following back rounded vowel did not differ significantly from labialized velars in formant transition frequencies. Lower F3 in labial-velar approximants indicates more lip-rounding but higher F2 suggests a more fronted tongue position. Locus equations show that rounded vowels following [kw] are less affected by coarticulatory rounding than following [w].