2.1. Stress patterns

Since metrification is at issue here, some discussion of Naasioi word stress is warranted. Stress normally falls on the second mora of words with three or more moras, as shown in (3) and (4), which suggests a peninitial pattern.

As can be observed in the data above, there is no evidence to suggest that coda consonants are moraic in the system, because stress does not shift as a function of the presence or absence of codas (e.g., [simpnoi] ‘naked’). The fact that codas are non-moraic will be raised again in the next section.

It is in smaller words that a different pattern emerges, and lends crucial evidence for the role that metrical constraints play in many of the other patterns to be explored. Observe the bimoraic forms in (5), which have stress on the first vowel:

This is apparently an avoidance of stress on the final mora in words.Footnote ²

In terms of stress placement, long vowels are treated as if they were sequences; that is, each vowel portion counts as a stress bearing unit (Hurd & Hurd Reference Hurd and Hurd1970). Stress therefore falls on the second half of a long vowel in initial position:

Since the default position for stress is the peninitial mora, when long vowels occur in this position, stress falls on the initial mora of the long vowel sequence:

This gives the appearance of a ‘final’ stress in disyllabic forms ending in a long vowel:

These generalisations around stress are largely due to Hurd & Hurd (Reference Hurd and Hurd1970), though independent data were collected and observed spectrographically. Stress acoustically involves a peak in F0 and amplitude. For forms which do not involve long vowels, this also involves an increase in duration. Some speakers (such as PG and AG) are clear in their judgements about the location of stress; thus, even if the acoustic cues turn out to be correlates of an accentual system, this does not nullify the results here, as the placement of the accent would still need to be determined by metrical properties.

Hurd & Hurd (Reference Hurd and Hurd1970: 38) note that stress is fairly robust, but make no mention of any evidence for secondary stress. Acoustic evidence suggests that in words with five or more moras, there is a stress on the second mora, and no other detectable pitch peaks or durational differences. This is true, for example, for [otmemoa] ‘to not have’. The lack of secondary stress will also be important for determining the overall prosodic behaviour of the language.

As mentioned, the generalisations above indicate a peninitial pattern with a constraint prohibiting final stress. One possible analysis is that the stress system is based on unbounded feet with initial extrametricality, as there are no apparent secondary stresses. While this type of system is not difficult to model, the presence of only a single unbounded foot makes certain predictions about the metrical parsing of the word – that is, that it is exhaustive (see also arguments against similar unbounded foot analyses in Bennett Reference Bennett2012). However, a different interpretation of peninitial stress based on bounded binary feet makes slightly different predictions. One possibility is that there is a single bounded iambic foot that is placed word-initially (Prince Reference Prince1985; Baković Reference Baković and McCarthy2004):

Such an analysis would predict that foot binarity is a relatively high-ranked constraint, though it also predicts that the word is not exhaustively parsed. It will be argued in the next section that evidence from prosody-sensitive allomorphy suggests that there is not simply a single foot, and that instead, the Naasioi word is exhaustively footed (aside from an extrametrical final mora), thus splitting the difference between these two approaches.

At this point, the consequences of stress avoidance on the final mora are not clear. A common analysis of the stress retraction found in bimoraic words is of a prohibition of a prosodic head in final position, yielding a shift in foot type from iambic to trochaic ( ) such that the word is exhaustively footed.Footnote ³ Alternatively, leaving the final mora extrametrical in bimoraic forms would yield a degenerate foot: ( ). Hung (Reference Hung1994: 88–89) entertains the degenerate-foot analysis for Axininca Campa, but rejects it on the assumption that foot binarity is an inviolable constraint. It will be argued, based on evidence presented in the next section, that the degenerate-foot analysis is correct for Naasioi, as the final mora does not appear to be computed in cases of allomorphy, and the prohibition appears to be one based on final feet, not on prosodic heads.

2.2. Present progressive allomorphy

Like many other Papuan languages of the region, Naasioi makes use of an elaborate system of verbal morphology. Each verb belongs to one of four conjugation classes. Verbs in each class have different properties, and for the most part take different forms of the suffixes to be outlined below, though several sets of suffixes overlap across different verbal classes. Some classes of verbs exhibit specific phonological properties (such as ending in nasals, or having similar bound vs. free forms), though these properties are largely irrelevant to the patterns to be discussed here. Aside from reduplication, the verbal morphology consists exclusively of suffixes. A detailed analysis and discussion of Naasioi verbal morphology can be found in Hurd & Hurd (Reference Hurd and Hurd1970). The verbal template includes a series of suffixes that mark (in order): object agreement, ‘auxiliary number’ (which marks non-singulars for either subject or object), subject agreement, number, negation and a series of tense/aspect suffixes. There are several verbal suffixes that exhibit allomorphic relationships, some of which are phonologically conditioned (Hurd & Hurd Reference Hurd and Hurd1970 provide an exhaustive catalogue of these affixes). The morphemes under discussion in this section are tense/aspect markers, appearing at the end of the suffix string. The basic patterns were first identified by Hurd & Hurd (Reference Hurd and Hurd1970), and were verified during fieldwork by the author.

The present progressive suffix -maa /-ma appears in the final position in the verbal template, and exhibits a length alternation that is contingent on mora count. The choice of allomorph is determined by a calculation of the mora count of the preceding string: odd-parity counts require -maa, while even-parities require -ma. Footnote ⁴ This is demonstrated with the pair of examples in (10), where the verb stem in (10a) has only a single mora, but where the presence of the additional monomoraic dual suffix -e in (10b) makes the mora count even.

An analysis of this pattern is that the alternation in length in the present progressive suffix is such that it consistently yields words with an odd mora count, a fact noted by Hurd & Hurd (Reference Hurd and Hurd1970). Several more examples are presented in (11) in order to illustrate this behaviour with various verbs and suffixes. The stem mora counts are included with the relevant allomorph for reference.

This is clearly a pattern of prosodically conditioned allomorphy (McCarthy & Prince Reference McCarthy and Prince1993b; Mester Reference Mester1994; Kager Reference Kager and Kleinhenz1996). The challenge that the above pattern raises is in accounting for the metrical structure of the output (i.e., to identify what formal property triggers the allomorphy), as well as the fact that the allomorph itself exhibits a metrical alternation (one vs. two moras). An analysis that ignores either of these facts will treat them as mere accidents. In addition, the preference for words of odd mora counts exhibited by this suffix is on the face of it somewhat mysterious for a metrical account, as it is not immediately clear what kinds of constituents will always result in an odd number of moras, though revisiting the patterns of word stress in the language uncovers a straightforward analysis.

2.3. The metrical structure of Naasioi words

Entertaining a system with binary feet as in (9) makes positive predictions in this case, as it suggests that length-based alternations may arise in order to satisfy metrical needs, though the ‘reach’ is limited to the first foot in the word. As is evident from the data above, Naasioi words are often longer than three moras. The assumption that the entire word is exhaustively footed, though with only an initially prominent iamb, makes predictions about whether output structures can satisfy metrical requirements. This effectively posits covert feet for the purposes of counting or other rhythmic properties (Halle & Vergnaud Reference Halle and Vergnaud1987; Halle Reference Halle1990; Poser Reference Poser1990; Crowhurst Reference Crowhurst1991; Hung Reference Hung1994; Bennett Reference Bennett2012; Golston Reference Golston2017). This will be the approach endorsed here, as it is the only way to account for the behaviours of the present progressive suffix.

The fact that there is a consistent mora parity in each case in (11) points to an analysis based on metrical principles. The resulting odd number of moras, as noted above, constitutes an outstanding problem, as feet are canonically binary, implying that the pattern should yield an even, rather than odd, number of moras. One possibility is that the system works like hypocoristic formation in many languages, where there is a template based on exhaustively metrified feet, to which a special affix is attached, and where the affix itself is not computed in the metrical structure (McCarthy & Prince Reference McCarthy, Prince and Goldsmith1995). The case of Japanese hypocoristics helps illustrate this idea, in that the truncated name is based on a bimoraic foot, but the suffix used for hypocoristics does not count in this computation (Poser Reference Poser1990). Excluding the suffix from the computation of mora counts in Naasioi, however, ignores the fact that the suffix itself exhibits an alternating number of moras.

The allomorphy resulting in words with odd numbers of moras is on the face of it an unusual or unexpected pattern, but makes sense in the context of the stress system of the language. As mentioned above, stress consistently falls on the peninitial mora. The only condition where this does not obtain is in bimoraic forms, where stress falls on the initial mora, as in (5). This behaviour is consistent with a constraint prohibiting stress on a final mora, which in the case of bimoraic words overrides regular stress assignment, yielding initial stress. The final mora, then, appears to be set off as extrametrical. If a nonfinality constraint is respected in the cases of allomorphy in question, then setting off the final mora as extrametrical will result in an otherwise consistently even-numbered mora count, one whose natural interpretation is of n binary feet, as in (13). In other words, considering the final mora extrametrical renders the rest of the word exhaustively parsed into binary feet when this suffix is present. This is illustrated with the metrical analyses of (11d) and (11e) given in (13):

This implies that a constraint like Nonfinality must be ranked relatively high. Nonfinality can be defined as in (14), which makes the most sense in a context where it is truly extrametricality, and not simply avoidance of a prosodic head, that is being enforced (see Hyde Reference Hyde2003, Reference Hyde, van Oostendorp, Ewen, Hume and Rice2011 for discussion). The reason for this is because in longer words there are only covert feet beyond the initial foot, and therefore there is no sense in which a prosodic head would threaten to be in the final position; instead, any footed material would trigger a violation.

In order to correctly model the Naasioi case of extrametricality, Nonfinality must dominate Parse-, which in turn interacts with Ft-Bin. The definition of Ft-Bin must crucially rely on part of the ‘under syllabic or moraic analysis’ clause, which is typically how the constraint is formulated (Prince & Smolensky Reference Prince and Smolensky1993).

While relatively important for phenomena such as the present progressive allomorphy, Ft-Bin is violated in some contexts. There is a bimoraic minimality requirement on words in Naasioi. For example, the lexical corpus of 456 items elicited from a basic Melanesian word list (Brown & Irvine Reference Brown and Irvine2021) does not include any monomoraic lexical words.Footnote ⁵ Examples of the smallest words are as below (including forms with long vowels, as in (17b)). Thus, if Nonfinality is respected in bimoraic forms, there must be degenerate feet. This yields a scenario in which a bimoraic minimal word does not equate a bimoraic foot; that is, the minimal word is not reducible to the minimal foot in the language (Crowhurst Reference Crowhurst1991; Garrett Reference Garrett1999).

As mentioned in §2.1, in bimoraic words, an initial stress would result in either a trochaic foot ( ) or a degenerate foot ( ). Under the former scenario, Ft-Bin $\gg $ Nonfinality (and Ft-Bin would also dominate a constraint on foot well-formedness, for example, one that demands right-headed feet, such as Iamb); under the latter, Nonfinality $\gg $ Ft-Bin. Since the allomorphy exhibited by the present progressive suffix is sensitive to covert feet, and thus Nonfinality must be defined as a prohibition on final feet (and not on prosodic heads), the shift in foot type from iambic to trochaic would not satisfy Nonfinality, as the final mora would still be footed. However, the structure with a degenerate foot plus extrametrical mora, ( ), would satisfy the constraint. This obtains if Ft-Bin is ranked sufficiently low, and monomoraic minimal words are ruled out because a degenerate foot on its own would violate Nonfinality. Importantly for Naasioi, Nonfinality must be respected, even if this is at the expense of a foot well-formedness constraint that demands that feet have a right-prominent mora, such as Iamb. In addition, Parse- must be violated because of the demands of Nonfinality, but this violation must be minimal in the sense that if extra moras are left unparsed in an uneconomical fashion, this would defeat the effect of the allomorphy. This dynamic is illustrated with the tableaux in (18) and (19), where competing allomorphs are listed in the input (following Mascaró Reference Mascaró2007). The ranking of Nonfinality $\gg $ Parse- ensures that (18a) (ba.k)(aa)(e.e) is selected over (18c) *(ba.k)(aa)(e.e)(maa).

While the allomorphy provides evidence for the metrical structures in question, the analysis is not limited to forms with the present progressive suffix. What can be inferred is that, based on evidence from stress and the minimal word, non-final ‘stray’ moras form degenerate feet, and thus violate Ft-Bin. Thus, in cases without the suffix present, potential parses are ( )() for even forms, and ( ) for odd forms. The present progressive suffix is simply a case of optimisation, where an exhaustive footing, that is, one where there are no unparsed moras, will emerge. This is illustrated in (20) with the lexical word [kopsina] ‘ankle’. The ranking of Parse-)(si) is selected over (20a) (kop)si, as both respect Nonfinality, but the former minimises the number of unparsed moras.

Forms with odd numbers of moras will exhaustively parse the moras into feet. This simultaneously satisfies Parse- and Ft-Bin. Forms with even numbers (larger than two) cannot satisfy both constraints and still respect Nonfinality. This is where their ranking becomes crucial. It is in the case of allomorphy that Ft-Bin emerges as relevant, guiding the choice of allomorph, and in contexts where Nonfinality is respected, all moras are otherwise exhaustively parsed into feet. Having a choice between two allomorphs which vary in length allows for this optimisation. Under normal circumstances, where this choice is not presented to the grammar, it will yield to Parse- by readily violating Ft-Bin, admitting a degenerate foot if there are any moras that would otherwise be left unparsed.

At this point, it is worth asking whether the above analysis of Naasioi stress is correct, and whether a reanalysis would alter the consequences for syllable integrity. It is evident from the behaviour of stress that if the system is constructed out of iambs, they are moraic iambs. These are accepted foot types under some theories of stress (Kager Reference Kager1993; see also Leer Reference Leer and Krauss1985; Crowhurst Reference Crowhurst1991; Rice Reference Rice1992; Driscoll Reference Driscoll2019), but not all, particularly those based on Hayes (Reference Hayes1995). Even though initial extrametricality is thought to be highly marked (Elenbaas & Kager Reference Elenbaas and Kager1999), an argument could be made that the system is constructed out of trochees which are offset from the left edge by initial extrametricality; that is, ( ). Thus, (bak)(aa)(ema) in the iambic analysis would under the trochaic alternative be represented as (ka)(ae)(maa). In fact, Lathroum’s (Reference Lathroum1991: 84–85) analysis of the reduplication and minimal word patterns in Naasioi posits a default trochaic foot. Under this scenario, in disyllabic forms Noninitiality would be violated in order to satisfy Trochee.Footnote ⁶ It will be demonstrated in §4, however, that re-analysing stress in this way yields exactly the same results in terms of syllable integrity violations. The obvious advantage that the iambic approach holds over the trochaic approach is in the relative infrequency of initial extrametricality, and the marked structure that Noninitiality demands. For these reasons, the iambic analysis will be employed in the remainder of this article.

2.4. Summary

This type of allomorphy, and the basic analysis sketched so far, are consistent with Kager’s (Reference Kager and Kleinhenz1996) treatment of Estonian, which exhibits a similar prosodically sensitive allomorphy. Both of these cases can be argued to be optimising. A point of contrast, however, is that the allomorphy outlined above is consistent with a stress system composed of quantity-insensitive syllables; in no case does what could be construed as a syllable coda disrupt the pattern by adding a mora. An alternative approach would view the matching between allomorph and stem as a property of subcategorisation (Paster Reference Paster2005), where the information that a short allomorph attaches to an even-numbered stem (and a long suffix attaches to an odd-numbered stem) is encoded into the lexical entry of the allomorphs. This approach views the fact that the allomorphs themselves differ in length as an accident, and must stipulate the subcategorisation information for any given allomorph. Severing the connection between the shape of the allomorph and the shape of the stem eliminates the optimisation that would otherwise be apparent in the metrical approach. Thus, the Naasioi case illustrates optimisation, where the length allomorphy in this morpheme creates exhaustively metrified feet.

Up to this point, all patterns can be accounted for under the assumption that syllable and mora are coextensive – that is, that all surface long vowels are simply sequences of short vowels. The force of Nonfinality has yielded final-mora extrametricality, but under the above assumption, this can be considered final-syllable extrametricality, and thus it does not pose a threat to syllable integrity, as each syllable by hypothesis only dominates a single mora (and thus its content cannot be split across feet). However, if this assumption is incorrect, there is the possibility that syllable integrity is violated. These violations would arise with the long vowels, if they can be shown to be monosyllabic, in cases where they would potentially be split across metrical structures, such as in the long forms of the present progressive suffix; for example, (ba.k)(aa)(e.ma). The next section will present evidence for syllables being non-isomorphic with moras, and will demonstrate that there are phonological operations which treat long vowels as a structural unit, that is, a vocalic root note associated with two moras, and by assumption, a single syllable.

3.1. Vowel shortening

The primary evidence for long vowels forming a structural unit comes from a process of vowel shortening. This is found morphophonologically with some roots, but much more robustly in reduplication. For instance, Hurd & Hurd (Reference Hurd and Hurd1970) note that the addition of certain affixes with class-4 roots triggers a shortening of a long root vowel: for example, boo-ai ‘He will die’ vs. bo-ie ‘He died recently’ (see also Lathroum Reference Lathroum1991: 87, fn. 6). Class-4 roots are extremely infrequent, and not many of these roots have long vowels. However, the implication of this shortening is that a syllable (with a long vowel) has to be targeted if $\mathrm {V}_{1}\mathrm {V}_{2}$ sequences are not affected by shortening. Related to this is the fact that there are other morphophonological alternations in length. Pronominal number markers appearing in the DP complex exhibit fluctuations in length: the dual suffix is a short [-e] which occurs before vowels, and a long [-ee] which occurs before consonants; the plural suffix surfaces as [-i] / [-ii] in the same environments (Hurd Reference Hurd1977: 154–155). This in part supports an analysis of long vowels as structural units.

In addition to this more marginal pattern, there is a shortening pattern found in some cases of reduplication. According to Hurd & Hurd (Reference Hurd and Hurd1970), verbs reduplicate derivationally, with sometimes unclear shades of meaning. In addition, other patterns have been identified, such as reduplication with nouns to form plurals, or with verbs to derive adjectives. Reduplication is partial, and prefixing. Reduplicants always consist of two moras, illustrated in (22).

As with the stress patterns outlined in §2.1, it appears that coda consonants (which can only be nasals or the glottal stop) are irrelevant to syllable weight, as they do not contribute a mora when they occur in the reduplicant (the presence vs. absence of these consonants in the reduplicant will be explained below).

The bimoraic shape of the reduplicant is consistent with the minimal-word phenomenon in the language noted above. Further evidence that the reduplicant is a prosodic word comes from stress, as both the base and reduplicant are stressed (as in sma-simi ),Footnote ⁸ and from the phonotactics of nasals, in that syllabic nasals are only allowed word-initially, and syllabic nasals are permitted initially in both the reduplicant and base:

The morphological structure of verbal forms is relevant to the shape that is derived in the reduplicant. As expected, bases with a monosyllabic, monomoraic root indicate that there is morphological overcopying in order to achieve a bimoraic foot in the reduplicant, as in (25), where the root in the base form is underlined. This will be relevant for the generalisations to be drawn regarding the strategies for copying root material, addressed below.

According to Hurd & Hurd (Reference Hurd and Hurd1970), there are two types of reduplicative output in the language, based on the phonological properties of the stem. They note that verb roots consisting of a long vowel exhibit a pattern where the entire root is copied. In other words, if the root contains only a long vowel, then this long vowel will surface faithfully in the reduplicant:

In addition to this shape-related fact, there are other markedness effects found in the reduplicant when the base includes these roots: for example, final glottal stops are deleted before other stops, even though glottal stop–stop sequences are phonotactically licit in lexical words; they are optionally deleted before nasals; and final nasals surface before vowels, but always as [] (implying that they are final in the prosodic word).

On verb stems not consisting of only a long vowel, the reduplicant will systematically shorten an initial long vowel, and final consonants will be deleted.

Thus, the following generalisations can be made. Reduplication yields a bimoraic reduplicant. It strives to copy only the root. If there is not enough material in the root, then it overcopies, likely a minimal word effect. A long vowel seems to be tolerable only if it is the only vowel in the root. What this means is that a long vowel needs to be counted as a unit, for cases where it shortens. Sequences of non-identical vowels, on the other hand, count as two separate syllables. In addition, there is evidence that creating a long vowel by reduplication is not disallowed over a juncture (as in (22c) ama-amako-ai or (26d) ii-iimui ). Therefore, it is not the case that adjacent identical vowels are disallowed, which argues in favour of the reduced reduplicant vowels being a single long vowel.

There are two things to note regarding vowel shortening. The first is that there is a separate set of processes that are triggered by a base, depending on whether it exclusively has a long vowel, or not. Since no other vowel sequences trigger this difference, this argues strongly for the grammar identifying long vowels as a single unit, while sequences are not. This suggests that long vowels constitute a single syllable associated with two moras ( la Hayes Reference Hayes1989). The second point is that in the cases of roots that are not exclusively made up of a long vowel, there is a process which reduces long vowels to short vowels in the reduplicant. This is a classic Emergence of the Unmarked effect (McCarthy & Prince Reference McCarthy and Prince1994), but it crucially does not affect sequences of non-identical vowels (i.e., deletion affecting one vowel in a sequence; that is, $\mathrm {CV}_1\mathrm {V}_2\mathrm {CV}_x$ $\mathrm {CV}_{1}\mathrm {CV}_x$ ).Footnote ⁹ This is consistent with Lathroum’s (Reference Lathroum1991) analysis of the language, whereby the nucleus of the reduplicant syllable is simplified. The fact that each type of reduplication also has different effects when it comes to consonants (and whether they are retained or not) indicates that the grammar must be sensitive to this length distinction. The overall generalisation, then, appears to be that reduplication can include either a single syllable with a single long vowel, or two syllables with a short vowel each (a sequence of vowels). Thus, reduplication provides evidence for long vowels being a structural unit. This, however, is only one step toward establishing that long vowels constitute a single syllable.

3.2. Truncation

Additional supporting evidence for long vowels constituting a single syllable comes from patterns of truncation, a phenomenon common in many dialects of Naasioi. While the minimal word in Naasioi appears to be bimoraic, truncated forms and hypocoristics appear to also be disyllabic. In these cases, truncation cannot yield forms which consist only of a long vowel. Names can be truncated to disyllabic structures (stress remains peninitial in the name, and initial in the hypocoristic):

The resulting forms are bimoraic, and can consist of two syllables, or of a sequence of two non-identical vowels (by hypothesis two syllables). However, while a name like Koivo can truncate to [koi], the truncation of a hypothetical name Koovo to *[koo] is rejected (and indeed no truncation is possible with this name). Names with long vowels in their first syllable exhibit this pattern in (28f) and (28g).

What this indicates is that hypocoristics may consist of a sequence of two vowels, but not a single long vowel. The implication is that a hypocoristic must comprise not only two moras, but two syllables. This pattern is reminiscent of patterns found in Japanese, which also makes extensive use of bimoraic feet, and in which minimal words are bimoraic, but minimal stems are disyllabic (Itô Reference Itô1990). This cannot be construed as a restriction on truncated forms that disallows segments with branching vocalic nodes, as this is clearly counterexemplified by forms like [mute]. A more straightforward account – the one adopted here – treats the truncation as prosodic (McCarthy & Prince Reference McCarthy and Prince1986; Weeda Reference Weeda1992; Downing Reference Downing2006).

3.3. Syllable-optimising allomorphy

One diagnostic for syllable structure discussed by Hyman (Reference Hyman2011) is the existence of syllable-optimising allomorphies. This would include cases which involve stems that select a C-initial suffix in the context following a vowel, and a V-initial suffix following a consonant. This would point toward syllable optimisation, even if it is an emergent phenomenon ( la Mascaró Reference Mascaró2007), as the phonology is selecting allomorphs which avoid vowel hiatus and which provide a best onset without creating a coda. This state of affairs obtains in the variation observed in the Naasioi number marking paradigm. Each overt allomorph of the number suffix is consonant-initial when following a vowel, for example, -de (du), -di (pl). However, the allomorphs are vowel-initial when following a consonant, for example, -e (du), -i (pl). This is consistent with a syllable-optimising allomorphy.

3.4. Consonantal distributions

One argument that Naasioi has syllable structure – not just moraic structure – comes from consonantal distributions. Naasioi allows only a limited set of consonant clusters, all intervocalic, aside from cases involving syllabic nasals. The first member of each cluster can be a nasal (assimilated to the place of a following stop) or a glottal stop: [p t k b d m n mp nt k]. The distributions of both the glottal stop and the nasal will be presented as evidence for syllable structure.

Hurd & Hurd (Reference Hurd and Hurd1970) claim that the distribution of glottal stop is limited to the syllable coda. There are several cases of intervocalic glottal stop [VV], and there is very little independent evidence for syllabification in these forms. However, given that glottal stop is not licit word-initially, and is licit both word-finally and before consonants, this suggests that it is a syllable coda. The fact that there are no *N sequences would also support the analysis of the glottal stop as a coda, as nasals can precede other stops. In addition, there is a set of allomorphs, the distribution of which supports the analysis of glottal stop as a syllable coda. According to Hurd & Hurd (Reference Hurd and Hurd1970), all class-1 verbs have the properties of phonological words. Relevant to this discussion, this means they all end in vowels, glottal stops or nasals. The indefinite object marker, which is used with class-1 stems in a detransitivised interpretation (e.g., backgrounding the object) is -k following vowels (as in (29a)) and - $\varnothing $ following nasals (as in (29b)). The class-1 verb subject suffixes which obligatorily follow the indefinite object marker are -am (1st person), -i (2nd person) and -u/-aa (3rd person, subject to allomorphic variation). Thus, an indefinite object marker will always be followed by a vowel. This appears to be an optimising type of allomorph selection (as per Mascaró Reference Mascaró2007), as -k would provide an onset for a following syllable, and - $\varnothing $ would allow the nasals to surface as onsets. As it happens, -k surfaces after a glottal stop (29c). The fact that glottal stop patterns with vowels in this respect suggests that it cannot be syllabified as an onset; if it could, the - $\varnothing $ allomorph would be expected.

The distribution of nasals is perhaps stronger evidence for syllable structure. Hurd & Hurd (Reference Hurd and Hurd1970) note that the alveolar and velar nasals are in complementary distribution, with the velar occurring only word-finally and before [k].

In clusters, nasals assimilate in place of articulation to a following stop. What can be deduced from these interacting sets of patterns is that place features are banned in the coda; that is, that the syllable coda does not independently license place features (Itô Reference Itô1989). The velar nasal surfaces in word-final position presumably because it lacks place features – a common analysis of Spanish and other languages (Harris Reference Harris1983, Reference Harris, Aronoff and Oehrle1984; Trigo Reference Trigo1988; Baković Reference Baković2000). Thus, rather than a disparate set of environments for place neutralisation (i.e., preceding consonants and word-finally), the two sets of patterns converge if [] is restricted to the syllable coda. If the line of reasoning established by Hooper (Reference Hooper1972), Kahn (Reference Kahn1976) and Selkirk (Reference Selkirk, van der Hulst and Smith1982) is followed, the environments which trigger place neutralisation involve the syllable coda. The moraic analysis of Hyman (Reference Hyman1985) would be highly dependent on linear phonotactic licensing statements to account for the fact that placeless nasals must be licensed pre-consonantally and word-finally, whereas a syllable-based approach reduces these environments to a single position, namely the coda. The number of environments for the glottal stop is larger and more diverse, as it occurs intervocalically, pre-consonantally and word-finally. As argued above, these environments can be subsumed under the syllable coda.

One additional related piece of evidence for syllable structure concerns the sequencing of nasals in the language. While nasals can occur pre-consonantally in word-medial position, they are limited to occurring before stops in these positions. Syllabic nasals occur word-initially. It is only in these contexts that a nasal–nasal sequence is tolerated (as in (31)), as underlying nasal sequences normally result in deletion of the first nasal (as in (32); see Hurd & Hurd Reference Hurd and Hurd1970: 65; Hurd Reference Hurd1977: 114).

These facts are difficult to capture straightforwardly under an analysis without syllables. If these distributions are attributed to the ‘syllabic’ nasal being dominated by a mora, this runs into the problem that all segments are ultimately dominated by moras in Hyman’s (Reference Hyman1985; Reference Hyman2011) analysis, as in (21a). The mora-only analysis would be forced to posit that nasal–nasal sequences are prohibited, which is generally true, except in cases with a syllabic nasal. If an exception is made allowing a nasal after the first nasal associated with a mora, this predicts that VN $_1$ .N $_2$ V sequences should also be allowed if N $_1$ happens to be the first nasal in the word, but such sequences are in fact banned. So the mora-only analysis would be forced to posit a strictly linear licensing condition: (only) nasals in initial position license a following nasal. In contrast, the syllable-based analysis allows the second nasal in #N $_1$ .N $_2$ sequences because N $_1$ is not a coda; medial VN $_1$ .N $_2$ V sequences are prohibited because the nasals in them are coda–onset sequences. The only stipulation required is that syllabic nasals are limited to word-initial position in Naasioi, which is a well-established pattern found cross-linguistically (Bell Reference Bell, Greenberg, Ferguson and Moravcsik1978: 160–161). While both approaches are potentially descriptively adequate, in the syllable-based approach the patterns fall out from normal licensing conditions on syllable structure.

3.5. Constraints on sequences

One final piece of evidence for syllables involves restrictions on vowel sequences. As Hyman (Reference Hyman1985, Reference Hyman2011) notes for Gokana, long sequences of vowels are possible, including long sequences of identical vowels. Naasioi also allows for extensive sequences of vowels; however, there are restrictions on identical vowel sequences. A search of the Naasioi dictionary reveals that there are no sequences of three identical vowels. There is only one headword with an uuu sequence, biuung ‘sling for slinging stones’, and one headword piuung ‘Doppler effect / whizz’ with an alternative pronunciation piuuung. These words are likely related, and also likely onomatopoetic. It is noteworthy that my consultants reject the forms with three vowels, and instead volunteer forms with two. It thus appears that there is a prohibition on trimoraic identical sequences.

There are also very few opportunities to derive sequences of vowels morphologically, as the right conditions are not normally present in the relevant roots and affixes (cf. Hyman Reference Hyman2015 for a related phenomenon in Gokana). For instance, Hurd & Hurd (Reference Hurd and Hurd1970: 43) note that class-2 bound verb stems do not end in a vowel, and it can be further noted that the most internal suffixes for class-3 and class-4 stems are consonant-initial. The structure of affixes appears to conspire against stacking identical vowels, and in cases where this might otherwise be possible, it is largely averted by allomorphy. For instance, [b] optionally surfaces as an allomorph of $\varnothing $ for the 3rd person direct object person suffix after vowel-final verb stems, which seems to reflect an emergent preference for a syllable onset (Mascaró Reference Mascaró2007). In contexts where the optional [b] does not surface, or where no object is present, forms with three identical vowels such as [nka-aa-mau] ‘they carry’ are possible. Baava Pirung speakers produce the form as [nkaamau], with vowel deletion, and South Naasioi speakers produce it with an epenthetic glottal stop breaking up the sequence: [nkaaamau].

An analysis can be entertained whereby any derived sequences of identical vowels undergo fusion, forming a single syllable (Poser Reference Poser1985). This appears to be the case for many morphologically derived long vowels in Naasioi. Under the mora-only approach, the prohibition outlined above would be explained as a prohibition on sequences of three moras dominating a single vocalic node. This could be nuanced, such that long vowels are created through fusion, and where the addition of an extra mora is prohibited (see Hyman’s Reference Hyman2011: 71–73 discussion of how maximal prosodic stem shapes in Gokana could be represented). However, under this theory, the prohibition appears largely stipulative. A more straightforward explanation would interpret the prohibition as holding over two adjacent syllables (one bimoraic, one monomoraic) with identical vowels, or simply as a ban on trimoraic syllables (Prince Reference Prince1990). In other words, fusion would fail in the event it would create a trimoraic syllable, and is resolved in South Naasioi by the insertion of a consonant, and in Baava Pirung by deleting the extra mora.

3.6. Summary

This section has presented arguments that long vowels constitute a structural unit and that they are tautosyllabic. Additional independent evidence for syllables comes in the form of segmental distributions and an onset-promoting allomorphy in the verbal morphology. Thus, there are independent pieces of evidence in Naasioi for syllable structure above and beyond the level of the mora. While there are questionable non-syllable explanations for each of these phenomena, they collectively receive a straightforward analysis with syllables.