Tone is distinct from other phonological phenomena both qualitatively and quantitatively (Hyman 2011), and has been instrumental in shaping phonological theory in many ways. However, the contributions to current linguistic theory of “grammatical tone’ (GT) – a type of non-concatenative morphology where a morpheme is expressed at least in part by tone and/or tone changes – have been less apparent. In this paper, we take stock of the types of GT patterns attested in the literature and the different theoretical treatments of GT that have been proposed to date. We show that GT is still to a large extent underexplored, and highlight the immense potential of the study of GT for improving our understanding of phonology and its outer limits. This paper serves as an introduction to the high-quality research articles collected in this special issue, which directly address how GT critically informs phonological theory and its current developments.

This paper presents both distributional and acoustic phonetic evidence for iambic stress in Tetsǫ́t'ıné (ISO: CHP), a Dene (Athapaskan) language with contrastive vowel length and four contrastive tones. In our acoustic study, we find that the primary correlate of stress in Tetsǫ́t'ıné is duration, whereas intensity plays a secondary but statistically significant role. There was no statistically significant effect on F0 in our results. We discuss our results in relation to several proposals regarding the typology of stress systems. Based on the Functional Load Hypothesis (Berinstein 1979) and Dispersion Theory (Flemming 1995, 2001), we find that our results are to some extent unexpected. We suggest that our results are most consistent with the Iambic–Trochaic Law (Hayes 1995), which predicts that iambic stress systems prefer to use duration as their primary stress correlate.

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.

This paper provides new evidence in support of the hypothesis that the syntax–prosody mapping of Intonational Phrases is flexible (Hamlaoui and Szendrői 2015). In the traditional ‘rigid’ approaches, Intonational Phrases are taken to map onto particular syntactic projections. In contrast, in the ‘flexible’ approach, the Intonational Phrase corresponds to the highest projection of the verb (HVP). Accordingly, the ‘flexible’ approach predicts that the HVP should also determine the size of Intonational Phrases in a language where the verb height depends on the utterance type. Our evidence comes from a language of this type, Iron Ossetic (East Iranian). First, we demonstrate that verbs in Iron Ossetic occupy different functional heads in different contexts. Then, based on novel prosodic data, we show that the HVP indeed directly determines the size of Intonational Phrases in clauses with narrow foci and negative indefinites. Additionally, in wh-questions, language-specific mapping constraints come into play.

This article considers the question of what constitutes item-based morphology, with a specific look at grammatical tone. Numerous case studies of grammatical tone are examined in light of the debate on whether morphology is item-based or process-based. In each case, tonal alternations are an exponent, sometimes the sole exponent, of some grammatical feature. Two of the case studies are examples of grammatical tone that can straightforwardly be analysed as involving concatenated morphophonological forms; however, in other cases, the grammatical tone cannot be reduced to the concatenation of a tonal affix or phonological feature with some stem. The latter type cannot straightforwardly be analysed as item-based, but if still phonologically predictable and productive, is not satisfactorily analysed as suppletive. This article suggests a set of diagnostics that can be used to determine whether a given phenomenon is best analysed as item-based, process-based or suppletive. Then, an analysis is presented in Cophonologies by Phase (CbP), where morphosyntactic features can be mapped not only to underlying phonological items, but also to morpheme-specific constraint weight adjustments. CbP allows for what may have been traditionally called item-based and process-based morphology to co-exist in a single framework.

Southern Pomo (Pomoan, California) displays a process of rhythmic vowel deletion (syncope) reflecting two mutually incompatible metrical structures. This phenomenon, called metrical incoherence, can be derived by an ordered sequence of independent subgrammars, that is, strata. Metrical incoherence is under-attested crosslinguistically, and the stratal models of phonology necessary to generate it have been criticised for predicting counter-typological phenomena. Nevertheless, the Southern Pomo data cannot be generated in more restrictive frameworks. This article argues that overgeneration is a necessary property of the phonological component, and that metrical incoherence is rare because it is difficult to learn. In Southern Pomo, this difficulty appears to have caused grammatical competition and restructuring: a second pattern of syncope, occurring in only a limited context, suggests that learners have reanalysed the grammar as having consistent metrical structure across the derivation. This work thus supports the proposal that diachronic change – and therefore typology – is constrained by extragrammatical factors.

This article posits a theory of iterative stress that separates each facet of the stress map into its constituent parts, or ‘atoms’. Through the well-defined notion of complexity provided by Formal Language Theory, it is shown that this division of the stress map results in a more restrictive characterisation of iterative stress than a single-function analysis does. While the single-function approach masks the complexity of the atomic properties present in the pattern, the compositional analysis makes it explicitly clear. It also demonstrates the degree to which, despite what appear to be significant surface differences in the patterns, the calculation of the stress function is largely the same, even between quantity-sensitive and quantity-insensitive patterns. These stress compositions are limited to one output-local function to iterate stress, and a small number of what I call edge-oriented functions to provide ‘cleanup’ when the iteration function alone fails to capture the pattern.

This paper develops a theory of footing in Harmonic Serialism (HS; Prince & Smolensky 1993/2004; McCarthy 2000, 2016) where Con contains only directionally evaluated constraints (Eisner 2000, 2002; Lamont 2019, 2022a, 2022b). Directional constraints harmonically order candidates by the location of violations rather than the total number of violations. A central result of adopting directional evaluation is that the constraint Parse($\sigma$) not only motivates iterative footing but also determines where feet surface. This obviates the need for alignment constraints (McCarthy & Prince 1993; McCarthy 2003; Hyde 2012a, 2016), which determine where feet are parsed in HS with constraints that count loci (Pruitt 2010, 2012). The theory uses fewer constraints, is empirically adequate, and makes more restrictive predictions than HS with counting constraints and parallel Optimality Theory (Prince & Smolensky 1993/2004) with directional constraints.

Dagaare is a language of northern Ghana and adjoining areas of Burkina Faso. There are two tones, H and L, and contrastive downstep H!H that involves a non-automatic pitch drop between two H tones. The challenge is to explain the extensive morphological conditioning of tonal processes, including dissimilation, downstep and spreading. Our solution involves level ordering: tones are introduced at different morphological levels (stems, words and phrases) and later processes can make earlier processes opaque. Tonal differences between nouns (spreading) versus verbs (no spreading) and stems (dissimilation) versus words (downstep) arise from constraint ranking differences within and across levels. There are two kinds of downsteps: stem-level downsteps are underlying L tones affiliated with some morpheme; word-level downsteps are L tones inserted by a general process of word-final lowering. Only one downstep per word is allowed. If more would arise, the morphologically inner downstep blocks the morphologically outer downstep.

Primary word stress is typologically diverse. In some languages, the metrical structure of a word predicts the location of primary stress, while in other languages it does not. This diversity is considered through the lens of Harmonic Serialism (HS), a serial constraint-based theory, and it is argued that HS must incorporate a limited degree of parallelism to capture the typology. Namely, primary-stress assignment is simultaneous with foot-building and also mobile, being (re)assessed throughout a metrical derivation. But incorporating this parallelism into HS is both possible and desirable: the positive typological consequences of HS are preserved, and the implied formal divergence between the prosodic word and the foot with respect to parallelism echoes a fundamental distinction that is visible in a wide range of extant theoretical and empirical findings.

This study examines phonological and phonetic properties of ATR contrasts in the vowel system of Akebu (Kwa). The sum of descriptive evidence, including vowel harmony, vowel distribution in non-harmonising contexts, vowel reduction and typological and etymological considerations, indicates a rare vowel inventory with an ATR contrast in front/back vowels but a height contrast in the three redundantly [−ATR] central vowels /ᵻ, ə, a/. This analysis was checked against four common acoustic metrics of ATR: F1 and F2 frequencies, spectral slope and F1 bandwidth size (B1). As expected, the results for the last three metrics were variable across speakers and vowel types, and are therefore inconclusive. The results for F1 were consistent but do not distinguish between ATR and vowel height. Two results nonetheless suggest the [−ATR] status of central vowels: they occupy the same belt of F1 frequencies and show the same position of observed-over-predicted B1 values as front and back [−ATR] vowels.

Features are standard in segmental analysis but have been less successfully applied to tone. Subtonal features have even been argued to be less satisfactory for the representation of African tone than tonal primitives such as H, M, L (Hyman 2010; Clements et al. 2010). I argue that the two-feature system of Yip (1980) and Pulleyblank (1986) offers a straightforward account of the tonology of Laal, an endangered, three-tone isolate of southern Chad – in particular properties of the Mid tone that are otherwise difficult to account for, namely the avoidance of complex patterns involving M, and a pervasive M-to-L lowering process, both straightforwardly analysed as subtonal assimilation. Other tonal operations in Laal are shown to involve full-tone behaviour, justifying a tone geometry à la Snider (1999, 2020) where subtonal features are linked to a Tonal Root Node, giving tones the ability to be either fully or partially active, just like segments.

This paper argues that tone-driven epenthesis is possible in tonal languages. In Wamey, an epenthetic [ə] is inserted to host a high tone in two contexts: first, to host a tone which would otherwise be left floating due to a restriction on rising tones (/cv̀cⒽ/ maps to [cv̀cə́] due to a ban *[cv̌c]); and second, to host a tone which is introduced by word-level morphology but is restricted from associating across a stem boundary. These patterns cannot be attributed to syllable phonotactics, which freely allow all consonants in the coda position. We assemble the evidence for tone-driven epenthesis, focusing on the distribution of final [ə] in lexical stem structure and [ə]-alternating suffixes. A simple OT analysis derives [ə]-epenthesis, utilising common constraints (e.g. *Rise, OCP(H), etc.) together with constraints against associating tone across prosodic boundaries. In total, Wamey epenthesis exemplifies the cultivation of segmental environments for the purpose of realising pitch targets.

Grammatical tone (GT) can be the sole exponent or a co-exponent of grammatical meaning (Hyman 2012; Rolle 2018), but there has been little discussion of how they distribute within a single language. In this article, I explore the relationship between tonal and segmental materials in Gyeli (Bantu A801, Cameroon), adopting a property-driven approach to phonological typology (Plank 2001; Hyman 2009). Gyeli has eight GTs in simple predicates, which serve as sole exponents of tense, aspect, mood and polarity distinctions and object-marking. When GT is a co-exponent accompanied by segmental material, for example, in auxiliary constructions, the information that the tonal component contributes to the meaning is insufficient to distinguish between grammatical categories: its functional load is weak. The decrease in functional load is correlated with an increase in length of a segmental co-exponent. This can be explained by the tonal cophonologies of segmental morphemes and their different GT dominance types.

Marlo et al. (2015) claim that Kuria verbal tone morphology undermines three well-established principles of locality and modularity: (1) Phonological Locality: the assumption that rules and constraints may only evaluate a small window of phonological objects; (2) Cyclic Locality: the stratal organization of morphophonology into stems, words and phrases; and (3) Indirect Reference: the claim that phonological rules and constraints cannot directly access morphosyntactic information. Sande et al. (2020) turn this claim into an argument for a new model of the morphosyntax–phonology interface, Cophonologies by Phase, which erases the separation between phonology and morphology and abandons standard locality domains in favour of syntactic phases. In this article, I show that the conclusions of both articles are unfounded: the Kuria data follow naturally from an analysis based on autosegmental tone melodies in a version of Stratal Optimality Theory which embraces all three restrictions, Phonological and Cyclic Locality and Indirect Reference, the latter implemented by Coloured Containment Theory. I argue that this approach obviates the technical and conceptual objections raised by Marlo et al. against a tone-melody analysis of Kuria, and makes more restrictive predictions about possible systems of tonal morphophonology compared to construction phonology frameworks.

Metathesis poses challenges for a typologically constrained theory of phonology: despite being simple to describe, its distribution is highly restricted, making it difficult to create analyses that make predictions while not overgenerating. Here, I investigate metathesis in Uab Meto (Austronesian; Indonesia), an understudied language with CV metathesis that is synchronic and productive. Drawing on original fieldwork, I argue that metathesis is not transposition, but instead a serial delete-and-spread mechanism (cf. Takahashi 2018, 2019). To support this, I present a deep case study into the language’s phonology, showing that metathesis arises from spreading, deletion and epenthesis patterns. I propose that synchronic metathesis systems like Uab Meto’s can only emerge from the successive application of these mechanisms, and hypothesise that true transposition, if it exists, only arises through morpheme-specific operations. This study thus presents a new look onto the typology of synchronic metathesis, and offers an explanatory account of its typological rarity.

Degenerate feet, even when forbidden in isolated words, can arise within phrases due to resyllabification. In particular, when a stressed monosyllable of the shape C0VC (where V is short) undergoes resyllabification in Latin and Ancient Greek, it yields a degenerate foot. While degenerate feet were tolerated in prose, they were avoided in hexameter verse. Even though a degenerate foot is a kind of light syllable, a light metrical position could not contain a foot. Verse evidence is used as a window onto the general prosodic structure of each language, revealing that speakers productively recognised degenerate feet and distinguished them from other prosodic categories.

A major issue in Bantu morphophonology is how to get the right tones in the right ‘cells’ in the verb paradigm. In many Bantu languages, grammatical tones are assigned to different positions in the verb stem depending on inflectional features of tense, aspect, mood (TAM), polarity and clause type: The same TAM may assign different tones (and different segmental allomorphs) in the affirmative vs. negative and in main vs. relative clauses. Although such ‘melodic tones’ (Odden & Bickmore 2014) are typically restricted to the verb stem (root + suffixes), often also the domain of vowel harmony and other segmental phonology, both the presence and mapping of grammatical tones within the stem cannot be determined without reference to the prefixal inflectional marking of subject, negation, TAM and object which precede the stem. In this article, we discuss three cases in Ekegusii, a Bantu language of Kenya, that require the stem-assigned grammatical tones to look ‘outward’ to morphological and phonological properties of such prefixes: (1) differential mapping according to whether the pre-stem tone-bearing unit is toneless, a derived H(igh) (from H-tone spreading), or underlyingly /H/ (Bickmore 1997, 1999); (2) presence of an object prefix in imperative and subjunctive forms and (3) initial/final tone agreement between the subject prefix and the final vowel of the verb (cf. Rolle & Bickmore (2022). We will show that Ekegusii provides extensive evidence that both the presence of grammatical Hs and their specific mapping, while targeting the stem (root + suffixes), must be ‘globally’ calculated on the basis of the entire morphosyntactic structure of the verb (including features exponed by prefixes).