Fundamental questions about the relative autonomy of and the nature of the interface between phonetics and phonology continue to stimulate a diverse range of responses. The articles in this special issue on the phonetics-phonology interface illustrate the complexity of the questions that underlie the on-going debates over how distinctive features are defined, whether categorical behaviour is indeed a unique and defining property of phonology as opposed to phonetics, how to account for gradient behaviour within the phonology, what constraints govern gradience and variability, how properties of gestural overlap impact on the notion of phonological unit or segment, where perception fits into the theoretical model in relation to articulatory and acoustic properties of production and phonological properties of mental representations, among others. The research reported on here draws on a diversity of analytical approaches and methodologies. Some approach the issues from the phonetics "upwards", as in the ultrasound studies of Derrick and Gick and the acoustic analyses of Shahin, while others, like Flynn and Kochetov and Alderete, initiate their investigations from the detailed examination of phonological patterns that seem to extend "downwards" into what has traditionally been deemed the domain of phonetics. The analyses are empirically rich, drawing on a wide range of data, some from more familiar languages and families (Germanic, Romance, Japanese, Austronesian) and others fromless well-documented groups (Niger-Congo), including a number of critically endangered languages (Salish, Wakashan, Pomoan, and Athapaskan). This is reflective of how over the past decades documentation of a broader diversity of languages and language families has expanded the empirical database of what is known about what properties languages may share and how languages may differ. A brief overview of the issues addressed by each paper follows.
Traditionally, categorical behaviour is deemed to be a hallmark property of phonology. The first article, "Individual variation in English flaps and taps: A case of categorical phonetics" by Derrick and Gick, challenges this claim, based on ultrasound evidence related to the production of the tap/flap variant of /t/ and /d/ in [End Page 303] English. Their data, from cases of articulatory conflict, show that individual speakers' unconditioned phonetic production of the subphonemic variants of the tap/flap is categorical. The subphonemic variants are alveolar tap, postalveolar tap, down-flap, and up-flap. Their finding challenges categoricality as a sure indicator that a given sound property has phonological status. Derrick and Gick expect that any of the subphonemic variants can function contrastively. They see this as emerging where individual speakers' contrastive usage diffuses throughout the language community, and so they urge more experimental focus on individual speakers' phonetic behaviour.
Gradience is standardly viewed as a, if not the, diagnostic for phonetic status, and this is the focus of the second article, "Acoustic testing for phonologization" by Shahin. This article first summarizes prevailing perspectives on the nature of phonetics and phonology, the phonetics-phonology interface, and phonologization, suggesting that the interface involves a monitor (tracking degree of gradience in phonetic data) along with the transducer (converting between the physical and cognitive) of Hale and Reiss (2000). Shahin then illustrates a procedure by which phonetic data can be inspected for degree of gradience to determine if a given sound property has phonetic or phonological status. The illustration involves acoustic data but the procedure can be used with any type of phonetic data, and it can reveal cases of language-specific phonetics. In the spirit of Myers (2000), she suggests that the procedure, as it results in clarification of what lies inside and outside phonology, will assist phonologists as they work to provide theoretical explanation for properties and patternings that are phonological.
It has long been known that degrees of articulatory difficulty and perceptual salience, known as "phonetic scales", relate to phonology, but it has not always been clear if the scales are part of the grammar and, if they are, whether they are innate or learned. These issues are addressed directly by the third article, "Patterns and scales of expressive palatalization: Experimental evidence from Japanese", by Kochetov and Alderete. The authors present comprehensive crosslinguistic and theoretical evidence, and evidence from speaker intuitions, for a distinction between two types of palatalization...