Assimilation of word-final nasals to following word-initial place of articulation in UK English

Using very large speech corpora, we can study rare but systematic pronunciation patterns in spontaneous speech. Previous studies have established that word-final alveolar consonants in English (/t/, /d/, /n/, /s/ and /z/) vary their place of articulation to match a following word-initial consonant, e.g. "ran quickly" "ra[ŋ] quickly". Assimilation of bilabial or velar nasals, e.g. "alar[ŋ] clock" for "alarm clock", is unexpected according to linguistic frameworks such as underspecification theory. The existence of systematic counterexamples would challenge that theory, but these might have been previously overlooked because they are infrequent. From the c. 8-million word Audio BNC (http://www.phon.ox.ac.uk/AudioBNC) we extracted over 14,000 tokens of relevant word pairs, to determine whether non-alveolar assimilations occur and with what distribution. Word and segment boundaries were obtained by forced alignment, and F1-F3 formant frequencies were estimated using Praat. Formant frequencies in assimilation environments were compared to non-assimilating controls (e.g. come back vs. come down). We present evidence that velar and bilabial nasals sometimes do assimilate, though possibly less frequently than alveolars.