This article introduces the blueprint model of production (BMP), which characterises the phonetics–phonology interface in terms of typed functions. The standard modular feed-forward view to the interface is that the phonetic form of a lexical item is the output of a phonetic module which takes the output of a phonological module as its input. The central idea of the BMP is that the phonetic form is instead the output of a higher-order phonetics function which takes the phonological function as one of multiple inputs. We explain how understanding the production process this way can account for systematic fine-grained variation in phonetic forms while maintaining a discrete phonological grammar. We present one possible instantiation of the model that simulates incomplete neutralisation, some cases of near-merger, and variation in homophone duration. Consequently, these types of systematic fine-grained phonetic patterns do not necessarily provide evidence against discrete, symbolic phonology.

The phenomenon of incomplete neutralisation describes a situation where a putative case of categorical phonological neutralisation is observed to be phonetically non-neutralising. This has been argued to be a problem for phonological theories that employ categorical features. Here, we use two distinct feeding orders of tone sandhi processes from Huai’an Mandarin to show that incomplete phonetic neutralisation is compatible with categorical phonological phenomena. Therefore, incomplete phonetic neutralisation does not automatically inform us of gradient phonological representations. We further show that incomplete phonetic neutralisation can in fact have a large effect size. Such results are not surprising from a classic generative view of phonology where linguistic performance is argued to be a multi-factorial problem, and linguistic knowledge (i.e., competence) is only one of the many factors involved. Furthermore, our results suggest that the observed incompleteness or gradience may have a source outside phonological knowledge.