2.1 Bondu-so and Dogon language overview

Bondu-so has two primary dialects—Kindige and Najamba—which have been described only in unpublished work by Hantgan (2013) and Heath (2017), respectively. The language has several properties that differentiate it from the other estimated 20 Dogon languages. Verb stems in all Dogon languages are agglutinative; while there are no prefixes, derivational and inflectional suffixes extend typically monosyllabic verb roots to multisyllabic stems; suffixes underspecified for [ATR] are susceptible to tongue root harmony from a root vowel. “Dominant” suffixes may instead impose their [ATR] value on the root vowel.

There is also evidence for a synchronic ten-vowel system in Bondu-so despite such a system being unattested elsewhere in Dogon. That is, [ATR] VH is attested within uncompounded stems among all the known Dogon languages, but Heath (2014: 2) argues that only the mid vowels participate in the harmony process while [a] and [i, u] are “…extraharmonic (or neutral) in the sense that they may co-occur with vowels of either harmonic set” (p. 2). Another disparity to consider between Bondu-so and some Dogon languages such as Tommo So (McPherson 2013; McPherson & Hayes 2016) is that the latter display height and backness harmony; in Bondu-so, there are remnants of height harmony in the formation of Imperative and Imperfective stems.

Our analysis of Bondu-so VH differs from McPherson & Hayes’s (2016) analysis of Tommo So VH in several ways, and markedly in our assumption concerning the lexical shape of a given verb. McPherson & Hayes assume that Tommo So verbs are lexically CVCV; the addition of a vowel-initial suffix involves a hiatus resolution rule, and alternations in what they consider to be a stem-final vowel are attributed to ablaut. We instead consider Bondu-so verbs to be lexically CVC. Accordingly, instances of hiatus resolution are fewer, and we assume that word-final vowels that arise in the Chaining and Past stems discussed below are epenthetic. In addition, we consider the vocalic alternations that McPherson & Hayes treat as ablaut to be another reflex of vowel harmony. An advantage to approaches appealing to ablaut is that the alternations witnessed are phonologically unpredictable; however, we would argue that these alternations are in fact predictable if one takes into consideration featural properties shared between vowels and sonorant consonants and the ability of their manner features in particular to spread from the stem vowel. We also note that Green & Dow (2017) independently arrive at a similar conclusion concerning lexical stem shape in Najamba, the second dialect of Bondu-so that is most closely related to Kindige, which we describe here.

In addition, Bondu-so has a nominal class system with alliterative agreement patterns that are far more elaborate than those found in neighboring Dogon languages. Nominal class marking is expressed through encliticization, which has no effect on the noun root in terms of VH, and a vocalic suffix which does influence the [ATR] value of the stem. Specific examples of suffix-controlled nominal stems are in Section 3.1.

3.1 Contrast and root-controlled harmony

Alternations in the Bondu-so Perfective suffix following obstruent-final roots provide insight into the language’s vocalic system. In Section 4, we discuss alternations following sonorant-final roots, as these often differ markedly from those following obstruent-final roots. The examples we present first in (2) reveal that tongue root values are harmonic across stems containing only mid vowels; a surface [ATR] contrast is clear in comparing [ɛ] vs. [e] and [ɔ] vs. [o].

Hantgan & Davis (2012) attribute the alternations between [-ee] and [-ɛɛ] to root-controlled [ATR] harmony; [+ATR] mid vowels occur after a root with a vowel of the same value, as in (2a–b), while [–ATR] mid vowels occur after [–ATR] root vowels, as in (2c–d). Hantgan & Davis propose that the lexical form of the Perfective third person singular suffix is a front, mid vowel that is underspecified for [ATR], namely /-EE/.⁵

These same suffixal alternations also emerge following roots with high and low vowels, as in (3), despite the fact that the surface root vowels exhibit only a single tongue root value. Examples (3b, d, e) illustrate stems disharmonic for [ATR], though they pattern exactly like those in (2) with mid vowels. That is, some roots with high and low vowels exhibit a [+ATR] suffixal vowel while others exhibit the [–ATR] value.

Hantgan & Davis (2012) take this paradox in disharmonic stems as evidence of an underlying [±ATR] contrast in vowels at all three heights. They attribute the surface neutralization of the underlying [ATR] contrast in low and high vowels to phonetically-based grounded constraints (Archangeli & Pulleyblank 1994) on the featural combinations *[–ATR]/[+HI] and *[+ATR]/[–HI].⁶ As a result of these constraints, they argue that the underlying ten-vowel system in Bondu-so is neutralized to seven values on the surface, with the [ATR] contrast maintained only in mid vowels.

Although Bondu-so words are often disharmonic for [ATR], via VH, the contrastive [ATR] value of the root is displaced and therefore maintained on the suffix in contexts like the Perfective. The outcomes are opaque, with VH appearing to have overapplied on suffixes following roots with high and low vowels.

Similarly opaque alternations arise throughout Bondu-so, such as in the nominal class system, where evidence for the underlying [ATR] value of the root vowel is reflected only on singular and plural suffixes. Like in the Perfective, the noun class 2 suffix alternates between both [ATR] values depending on the value of the vowel of the root to which it attaches. Transparent instances of noun stems undergoing VH are in (4), whereas the contrast is lost on the root if the root vowel is high or low as in (5) and (6), respectively.⁷

Hantgan & Davis (2012) propose that such disharmony results when a root’s [ATR] feature is delinked via one of two clean up rules, represented here in Figure 1a, b. They invoke these rules in order to satisfy the phonetically-based grounded constraints referenced above.

Figure 1

Spreading and delinking (Hantgan & Davis 2012).

We, too, attribute such disharmony to featural incompatibility, yet we attribute delinking to constraints on surface well-formedness. Roots with antagonistic feature combinations delink [ATR], but crucially after [ATR] has spread from the root vowel to a suffix vowel that is unspecified for the feature. The resulting stem is disharmonic but does not violate well-formedness restrictions on “tense low” and “lax high” vowels.

In Section 6.1, we discuss further Bondu-so suffixes that are specified for [ATR] and, as such, yield different outcomes.

3.2 Summary

In this section, we presented data representing Bondu-so’s basic root-controlled VH patterns and accordingly discussed the motivations underlying Hantgan & Davis’s (2012) analysis. To summarize their analysis: i) the feature [ATR] is binary; ii) neither value of [ATR] is dominant; and iii) a suffix underspecified for [ATR] receives this feature via spreading from the root vowel.

The data we present in the next section also concern root-controlled VH in Bondu-so but go beyond those discussed by the aforementioned authors. While [ATR] remains a key factor in alternations seen among these additional data, we illustrate that roots ending in sonorants intervene in featural spreading, resulting in disparate suffixal alternants after obstruent-final vs. liquid-final vs. nasal-final roots. We propose a feature geometric analysis that relates these outcomes to the presence vs. absence of particular vowel manner (V-Manner) features in the geometry of a given type of consonant that ultimately affect the outcomes of VH. Our analysis accounts not only for these new data, but also easily accounts for all data presented in Hantgan & Davis (2012), including those that were somewhat more problematic and led to the additional invocation of floating features.

4.1 Divergent alternations

Vocalic alternations arising from VH following sonorant-final roots differ from the basic patterns shown in Section 3.1. There, we saw that Bondu-so suffixal mid vowels alternate under the influence of root-controlled VH between two expected pairs of harmonic counterparts: [ɛ] vs. [e] and [ɔ] vs. [o]. In Section 4.1.1, we first revisit the Perfective stem and bring to light new data that illustrate markedly different alternations following liquid-final and nasal-final roots. We show that, in the Perfective, suffixal alternations following liquid-final roots are identical to those observed following obstruent-final roots (i.e., [ɛ] vs. [e]) but that alternations following nasal-final roots are different (i.e., [ɛ] vs. [i]). We then turn to data from the Chaining stem that diverges even further from these patterns; we introduce instances in which [ɛ] alternates with [Ø] (i.e., null). These alternations call into question an analysis based solely on [ATR] underspecification of suffixal vowels.

4.2 Data summary

The behavior of Perfective stems with sonorant-final roots, as well as all Chaining stems, brings to light several issues that must be resolved in any analysis of Bondu-so VH. In sonorant-final roots, we see that beyond the expected [-ee] and [-ɛɛ] allomorphs of the Perfective, a third allomorph [-ii] emerges following nasal-final (but not liquid-final) roots. An analysis based on [ATR] underspecification and root-controlled spreading alone cannot predict the emergence of the [-ii]. As such, some other property, ostensibly due to or stemming from the nasal, appears to intervene and affect harmonization.

The outcomes in Chaining stems are different; a root can be followed either by [-ɛ], [-i], or by no vowel at all. We would like to propose that these outcomes arise due to two interacting factors. To begin, the fact that a vowel is absent following some roots suggests to us that perhaps the stem-final vowel in these verbs is epenthetic, rather than being associated with the realization of some morphological exponent of these verb contexts. If we are correct, it would therefore appear that the quality of the epenthetic vowel is (like the suffixal vowel of the Perfective stem) determined by the featural properties of the segments that precede it, but only partially by the [ATR] specification of the root vowel. The subsidiary distinction between obstruent-final roots and sonorant-final roots once again shows that other factors are involved in the stem-final vowel’s quality.

A second issue relates specifically to sonorant-final roots and the conditions governing whether they require an epenthetic vowel or not. We take up this issue in Section 7.3.

With these new patterns of root-controlled VH established, we next turn to formalizing these relevant outcomes. In Section 5, we offer an analysis inspired by the principles and representations proposed in the Parallel Structures Model of feature geometry (Morén 2003a; b; 2006; 2007). We illustrate that two modifications of this model allow us to transparently capture not only the more straightforward outcomes of Bondu-so VH discussed in earlier work, but also certain more complex alternations, like those introduced in this section. In Section 7, we extend this analysis to other contexts that were analyzed using floating features by Hantgan & Davis (2012).

5.1 Modifications to the PSM

We propose two modifications to the standard PSM approach. First, we assume, following other models of vowel geometry, that [ATR], as opposed to [lax], suitably captures vocalic behavior cross-linguistically (Odden 1991; Vaux 1996; Halle et al. 2000, among others). This is more of a conceptual modification, rather than one that affects the architecture of the model itself. A second modification that we propose is more substantive but nonetheless grounded in cross-linguistic vocalic tendencies discussed elsewhere. That is, our data suggest that the V-Manner features [closed] and [ATR], rather than being independent of one another, instead pattern together in notable ways. This fact becomes is particularly apparent in that the feature [ATR] is licensed in surface representations only alongside [closed].

Thus, we propose that [closed] and [ATR] form a constituent or node under V-Manner but separate from [open]. This supposition is far from unexpected; the features [closed] and [ATR] tend to cluster together cross-linguistically, prompting Odden (1991), for example, to propose that they function as two features branching under a height node. This is also supported by typological perspectives offered in different frameworks, such as in Archangeli & Pulleyblank (1994), which form the basis for the grounded constraints on incompatible height/[ATR] combinations that Hantgan & Davis (2012) employed in their earlier analysis of Bondu-so VH.

We acknowledge that such a modification poses an issue concerning the “parallel” nature of the PSM. However, given that the nodes proposed in the PSM are strictly organizational in nature (Morén 2006), the introduction of another level of structure within the V-Manner node seems not to be expressly precluded. Of course, one might ask whether there is evidence for such an interrelationship between [closed] and [ATR] under C-Manner itself. Absent such an investigation, we would argue nonetheless that the introduction of a separate height node containing [closed] and [ATR] (at least under V-Manner) improves upon the basic architecture of the PSM approach given that it is supported both cross-linguistically and typologically. Indeed, we illustrate below that the height node plays an important role in our analysis of Bondu-so VH. The modified structure for Manner features that we assume is represented in Figure 3. Because Place features play no substantive role in the phenomena under consideration, we have chosen to omit C-Place/V-Place trees from the figures below.

Figure 3

Modified PSM – Manner features.

The structure given in Figure 3 provides a means to represent the role played by the presence vs. absence of particular features in our modified PSM approach to Bondu-so VH.

5.2 Vowel inventories

The limited set of features that we propose in our PSM-style analysis not only captures the vowel contrasts present in Bondu-so but also motivates the absence of certain surface vowels. In Table 1, vowels in shaded rows are part of the phonemic inventory but do not surface. In addition, the featural specifications that we propose in Table 1 make certain predictions about the surface distribution of these vowels that are supported elsewhere in the language and in the outcomes of VH.

The V-Manner features represented in Table 1 correspond to those utilized in the PSM, with the exception of the substitution of [ATR] for [lax] discussed above. While it is not of an immediate concern in our analysis, we utilize V-Place [dorsal] to differentiate “front” vs. “back” vowels as features like [round], [back], and [front] are not typically assumed in the PSM framework. Note that there is independent evidence that /a/ and /a̘/ pattern with other “back” vowels in Bondu-so; as such, we assume that the featural specification of the low vowels also includes V-Place [dorsal]. (For more on the patterning of low vowels in Bondu-so, see Section 7.)

Given the proposed featural specifications for Bondu-so vowels in Table 1, we can now make several key observations. Each vowel in Bondu-so must have at least one V-Manner feature in its geometry; however, the only feature licensed to occur on its own is [open], as with [a]. Vowels with a fully-specified [height] node (i.e., containing both [closed] and [ATR]) are licensed on their own in the absence of [open], as with [i] and [u]. Vowels with a fully-specified V-Manner node (i.e., containing [open], [closed], and [ATR]) are also possible, as with [e] and [o].

We find, however, that while vowels whose only V-Manner feature is [closed] are part of the phonemic inventory, they are not licensed in surface representations in the absence of another V-Manner feature; this accounts for the absence *[ɪ] and *[ʊ]. Rather, [closed] can occur on the surface without [ATR], but only when accompanied by [open], as we find with [ɛ] and [ɔ]. The presence of [open] satisfies a higher level licensing condition that at least one V-Manner terminus must be saturated.

That [ATR] is licensed only by [closed], as in [i] and [u], which occur in the absence of [open], also speaks to the higher level licensing condition; vowels are licensed in the absence of [open] if both termini of the [height] node (and hence one branch of the V-Manner node) are filled. The opposite combination, however, is not attested. That is, [ATR] is not licensed by [open], as we see in the absence of [a̘].

Surface vocalic outcomes in Bondu-so support our proposal of a [height] node under V-Manner, with [closed] as the head, directly governing [ATR], as depicted in Figure 3. The two branches of the V-Manner node illustrate no obvious asymmetry or head/dependent relationship. As stated above, the fact that [closed] can appear without [ATR] in the presence of [open] is due to other factors. In the next section, we provide the specifics of the proposed PSM analysis of Bondu-so VH.

5.3 Vowel harmony with PSM V-Manner features

Hantgan & Davis (2012) analyze Bondu-so VH as involving [ATR] spreading. We agree, in principle, but differ in our assertion that spreading is due to a single, privative [ATR] feature, rather than spreading of [+ATR] vs. [–ATR], depending on the value of the root and/or suffixal vowel. We illustrate the basic components of our analysis by first returning to root-controlled [ATR] spreading in the Bondu-so Perfective stem. Our privative approach assumes that the Perfective suffix is unspecified for [ATR]; Hantgan & Davis (2012) instead proposed that it is underspecified for this feature. This subtle distinction has important consequences.

Recall that the two vowels in the Perfective suffix that emerge after obstruents and liquids are [e] and [ɛ]. The featural specifications for vowels we offer in Table 1 show that the only distinction between [e] and [ɛ] is the presence vs. absence of [ATR], with the latter lacking this V-Manner feature; see Figure 4.

Figure 4

Underlying featural representation of the Perfective suffix.

Thus, the Perfective suffix, being unspecified for [ATR], has [ɛ] for its basic form. However, under the influence of a root vowel specified for [ATR], this feature spreads to the suffixal vowel. The result of spreading fills the empty terminal branch with [ATR], resulting in [e], hence the alternation between [ɛ] and [e] in Figure 5. If the root vowel is unspecified for [ATR], no spreading occurs, and the Perfective suffix exhibits its basic form, [ɛ]. Such outcomes can be seen by comparing examples given above in (3) and (4). We discuss below the third alternant of the Perfective suffix, namely [i], which occurs after nasal-final roots.

Figure 5

ATR spreading: Obstruent root to the Perfective suffix.

The intervening root-final obstruent appears to play no role in mediating the spreading of [ATR] from the root vowel to the suffix. We attribute this to the fact that obstruents have no V-Manner features that would support the spreading of [ATR] to the obstruent. Recall that there is no vowel, underlying or phonemic, that exhibits only V-Manner [ATR] in Bondu-so. We propose below that licensing and headedness relationships, as well as the well-formedness constraints found in Bondu-so vowels, also apply to sonorants in the language.

We would, of course, be remiss without addressing the outcomes with underlying root vowels /ɪ/, /ʊ/, and /a̘/, which have no surface counterparts in the language. Beginning with /ɪ/ and /ʊ/, these root vowels have no [ATR] feature to spread to the Perfective suffix; however, they are later assigned [ATR] due to a surface constraint on lax high vowels. Root /a̘/ is specified for [ATR] and therefore can spread this feature to the Perfective suffix; however, this vowel later loses its [ATR] feature by way of an analogous surface constraint on tense low vowels.

With these basic harmonic alternations between [ɛ] and [e] motivated, we turn to the behavior of liquid-final vs. nasal-final roots. Recall that vowels in the Perfective suffix following liquids pattern like those following obstruents, but those after nasals pattern differently. We attribute the difference to the unique combination of features in the geometry of each class of consonants, and each consonant’s influence on feature spreading from root vowel to suffix.

The alternation in the Perfective suffix after nasals is between [ɛ] and [i]. We propose that this outcome arises due to the fact that Bondu-so nasals, like proposed for those in Serbian (Morén 2003a) and Bothoa Breton (Iosad 2012), exhibit V-Manner [closed] but lack V-Manner [open]. The presence of V-Manner [closed] on the nasal licenses local spreading of [ATR] from the root vowel; recall that [closed] similarly licenses [ATR] in Bondu-so vowels. The local spreading of [ATR] yields a saturated and licit V-Manner node. We propose that because combinations of [closed, ATR] are licit in Bondu-so, spreading of the entire V-Manner node to the suffixal vowel is licensed, ultimately resulting in [i]. Recall from Table 1 that the featural specification for [i] is in fact [closed, ATR]. The outcome of featural spreading in nasal-final roots is formalized in Figure 6 and seen in the examples given above in (8).

Figure 6

ATR spreading: Nasal root to Perfective suffix.

The outcomes following roots ending in liquids in the Perfective differ from those ending in nasals in that the former pattern with other obstruent-final roots in witnessing an alternation in the Perfective suffix between [ɛ] and [e]. We propose that the influence of Bondu-so liquids is different due to their unique featural specification. The patterning of Bondu-so liquids suggests that they are specified V-Manner [open, closed]. This differs from what has been suggested for other languages analyzed under the PSM, but it is far from unexpected. Pembrokeshire Welsh and Bothoa Breton (Iosad 2012) liquids are said to exhibit V-Manner [open] while liquids in Serbian (Morén 2003a) are instead V-Manner [closed]. Of course, there is no prohibition in the PSM that prevents liquids in some language from expressing both features. If vowels are uncontroversially able to exhibit both features, then the “parallel” nature of the PSM would suggest that the same would apply to relevant consonants. Indeed, the behavior that liquids have on Bondu-so VH strongly supports this assumption.

Because liquids exhibit V-Manner [closed], they also permit local [ATR] spreading from the root vowel; as in the case of the root-final nasals described above, the presence of the licit V-Manner node in liquids licenses spreading of the node to the suffixal vowel. The resulting suffixal vowel following liquids is [e], which is accordingly specified [closed, open, ATR]. The result of spreading within a stem with a root-final liquid is represented in Figure 7 and seen in words like those given above in (7). Note that the crucial difference between Figures 6 and 7 is the absence vs. presence of the feature [open] in the root-final consonant, respectively.

Figure 7

ATR spreading: Liquid root to Perfective.

Thus far, we have motivated vocalic alternations in the Perfective suffix by referencing the role played by features exhibited by root-final consonants of different types. We turn next to alternations involving epenthetic root-final vowels in the Chaining stem. We first discuss [ɛ]~[i] alternations in the Chaining stem in non-phrase final verbal contexts involving obstruent-final roots; recall that obstruent-final roots in the Perfective stem instead manifest [ɛ]~[e]. We will once again address the outcomes in reference to featural licensing but suggest that the differing outcomes in Perfective and Chaining stems arise from the featural characteristics of the Perfective suffix vs. epenthetic vowels, respectively. We will reserve discussion of the otherwise unexpected alternation between [ɛ] and [Ø] that arises after sonorant-final [ATR] roots in Chaining stems for Section 7.3.

Our analysis assumes that the Perfective suffix is unspecified for [ATR]; as such, we propose that its feature specification is V-Manner [open, closed] and that its empty [ATR] terminus is filled by spreading wherever applicable from a root vowel specified for this feature. The alternations observed in Chaining stem data, as in the examples in (9) and (10) above, however, suggest that the epenthetic vowel associated with the formation of these stems is specified only for V-Manner [closed]. This epenthetic vowel is schematized in Figure 8.

Figure 8

Proposed features of epenthetic Chaining/Past vowel.

The Perfective suffix, with its V-Manner [open, closed], licenses a surface vowel, but the underlying featural specification of the epenthetic Chaining vowel does not and must be augmented by another feature in order to be realized. In the simplest of instances, namely those in which a root ends in a consonant and contains a vowel unspecified for [ATR], the epenthetic vowel receives [open]. The combination V-Manner [open, closed] results in [ɛ]. This combination appears to represent the minimal featural repair necessary to license a vowel. Although the addition of [ATR] is arguably another option, it seems not to be the preference in Bondo-so.

In those instances where the Chaining root vowel is instead specified for [ATR], two possibilities arise. For obstruent-final roots, the outcome is like that in Perfective stems. The root vowel’s [ATR] feature spreads as elsewhere to the epenthetic vowel. [ATR] fills the empty [height] terminus alongside [closed] and precludes the assignment of [open], thus resulting in [i]. The spreading of [ATR] in obstruent-final Chaining stems is represented in Figure 9 and is seen in examples like those given above in (9). Sonorant-final roots whose vowels are specified for [ATR] spur different outcomes and are discussed in Section 7.3.

Figure 9

ATR spreading: Obstruent-final root to epenthetic vowel.

Our analysis of root-controlled VH in Perfective and Chaining stems of different types illustrates the importance of the root-final consonant in dictating Bondu-so VH patterns. We have captured not only transparent alternations between well-known “harmonic counterparts” but also those alternations that cross-cut vowel heights. We will take up our discussion of the curious “zero” alternation in nasal-final Chaining stems in Section 7.3 where we propose correlations between the presence of [ATR], moraic licensing, and a bimoraic minimality condition on Bondu-so verb stems. In the next section, we briefly outline a licensing approach to instances of what has earlier been analyzed as suffix-controlled harmony in Bondu-so.

6.1 Suffix-controlled harmony

Hantgan & Davis (2012) interpret suffixal vowel alternations in the Perfective stem and in singular/plural noun pairs as being due to root-controlled [ATR] harmony, but they also discuss other verbal and nominal contexts in which root vowels themselves alternate. Thus, root vowels alternate before suffixes that are said to be lexically-specified for some value of [ATR], leading these scholars to propose that neither the plus nor minus value of [ATR] is dominant. That is, they attribute some alternations to suffixal [+ATR] spreading, as in the formation of Bondu-so stems like the Infinitive in (11). Others, they attribute to [–ATR] spreading, as in the Mediopassive in (12).¹⁰ The proposed underlying root forms for each example allow us to illustrate that the suffixal [ATR] value has spread onto the root, overriding its underlying [ATR] value to agree with that of the suffix.

The approach we adopt below instead assumes privative [ATR] and that the presence of [ATR] is dominant. In doing so, we account for instances of suffix-controlled, dominant harmony by appealing to morphological and prosodic asymmetries between certain dominant suffixes and the root itself. Though not necessarily a novel approach, by appealing to Positional Licensing (e.g., Ito 1986; Goldsmith 1990; Steriade 1994; Lombardi 1995; Ito & Mester 1999; Walker 2004), we assert that only stems headed by a suffix specified for [ATR] license the retention of [ATR] on their root.

As in other instances of suffix-controlled harmony, like those discussed by Casali (2008), we assume that there is a structural asymmetry between dominant affixes and a preceding root. Under the approach that we propose here, suffix-controlled harmony arises in Bondu-so word formation in those instances where a suffix projects a new prosodic word (PWd). In doing so, the affix becomes both the morphological and prosodic head of the resulting word, with some of its features percolating (Lieber 1980) and subsequently trickling down to structurally lower PWds. If such a dominant affix is specified for [ATR], the feature will override the [ATR] specification of a PWd that comes before it, even if this PWd is the root. We envision such an outcome being structurally represented as in Figure 10.

Figure 10

[ATR]-dominant suffix-controlled harmony.

Such a structural approach to suffix-controlled VH can account for what Hantgan & Davis (2012) analyze as [–ATR] dominance, without appealing to featural binarity. If an affix such as the Bondu-so Mediopassive seen in (12) is unspecified for [ATR] but structurally higher than the preceding root, the absence of the [ATR] feature on this morphological and prosodic head fails to license the retention of this feature on lower PWds. This, thereby, results in the loss of the feature and an apparent regressive harmonization for “lax” vocalic values. We schematize this outcome in Figure 11.

Figure 11

[ATR]-dominant suffix-controlled harmony.

In the next section, we illustrate that by combining our PSM-style analysis and the Positional Licensing approach proposed above, we can successfully account for certain more problematic cases of Bondu-so VH discussed by Hantgan & Davis (2012), and namely those alternations involved in the formation of Imperative and Imperfective stems. The former involves yet another pair of harmonic alternants, namely [a] and [o], which led these authors to posit that a floating [+ATR] feature to capture observed outcomes. Our PSM-style approach requires no such machinery. The Imperfective stem presents an additional challenge in that it appears to involve both root-controlled and suffix-controlled VH. We show that our approach adequately accounts for these outcomes as well.

7.1 Imperative stems

The Imperative stem involves suffixation of a short vowel that alternates between [o] and [a]. The examples in (13) illustrate that the former arises after [ATR] roots, with the exception of roots with /a̘/, which take [a]. The latter is found in all instances after roots whose vowel is unspecified for [ATR], like those in (14), despite the fact that root vowels, including mid vowels, other than /a/, surface “tense.”

The challenge presented by the Imperative stem is two-fold. One issue is in the behavior of suffixal vowels which alternate between [a] and [o]. We have not yet witnessed such an alternation elsewhere in Bondo-so. A second issue is that all vowels except [a] surface “tense,” irrespective of the root vowel specification for [ATR]; this is reminiscent of what we saw above with suffix-dominant harmony, as in the Infinitive, though the vowels of the Infinitive suffix itself did not alternate. The analysis that we propose below stems from principles we have established thus far for other verb contexts.

Crucially, our analysis assumes that the Imperative suffix is specified V-Manner [open, ATR] but unspecified for V-Manner [closed], as represented in Figure 12. As we have shown elsewhere, this featural combination is disallowed on the surface though it is arguably part of the phonemic inventory, given evidence for roots with underlying /a̘/.

Figure 12

Proposed features of Imperative suffix.

For the non-low verb roots specified for [ATR], such as those in (13a–d), we propose that root vowels are specified as V-Manner [closed, ATR]. We further suggest that [closed] spreads (as [ATR] has elsewhere) to fill the empty terminus in the suffixal vowel’s geometry, yielding [o], as in Figure 13. The [ATR] feature need not spread because it is already specified in the suffixal vowel geometry.

Figure 13

[closed] spreading to Imperative.

Verb roots like example (13e) are specified V-Manner [open, ATR], as is the Imperative suffixal vowel. Thus, there is no opportunity for spreading of [closed]. In both instances, this disallowed featural configuration is resolved to [open] on the surface, as it has been elsewhere in the language. A similar outcome arises in examples like (14e) where the root vowel is specified only as V-Manner [open]; again, there is no opportunity for [closed] spreading. Roots like those in examples (14a–d) are specified underlyingly for V-Manner [closed]; however, it appears that [closed] cannot spread in the absence of [ATR], as we have seen elsewhere in Bondu-so. The suffix vowel is [a].

As we alluded to above, on their own, the underlying features of the Imperative suffix (i.e., /a̘/) cannot license a surface vowel and must be adjusted in order for a vowel to be expressed. One possibility, the delinking of [ATR], is widely-attested in the language. The other option is the addition of [closed], which we have proposed occurs via spreading from the root vowel, wherever possible. Thus, this accounts for the suffixal alternation between [o] and [a].

There are at least two possibilities to address the alternations seen in roots lacking an underlying specification for [ATR] in (14). One possibility is to invoke the perspective we motivated in Section 6 concerning the behavior of [ATR] in structurally-dominant suffixes. The Imperative stem would behave like the Infinitive and Mediopassive stem in that the underlying [ATR] specification of its suffixal vowel comes to be distributed over preceding material in the stem due to a combination of structural dominance and licensing, despite the feature being later removed to satisfy a constraint on well-formedness. This approach would require an arguably uncontroversial series of two rules: one involving a morphophonological rule of [ATR] percolation/trickling and a second to satisfy a surface well-formedness constraint. Both these rules are independently attested elsewhere in Bondu-so.

Another possibility would be to propose that the Imperative stem entails a context-specific rule that generalizes the constraint that we have elsewhere seen applied to /ɪ/ and /ʊ/ that disallows vowels specified only for [closed] in the absence of either [ATR] or [open]; these vowels would alternate to [i] and [u] by the addition of [ATR] to their geometries. If this rule were generalized to mid vowels, it might require any vowel underlyingly specified for [closed] (regardless of whether [open] is present or absent in the geometry) to acquire [ATR]. Thus, all mid vowels under influence of this rule would surface [e] or [o]. This possibility, too, has a precedent in the behavior of lax high vowels elsewhere in the language. Future research will be necessary to tease apart which of these options best captures the otherwise unusual behavior of mid vowels in the Imperative, which surface “tense” despite being underlyingly unspecified for [ATR] while also being followed by a suffixal vowel that is also (underlyingly) unspecified for this feature.

In any event, both of these possibilities present independently-motivated mechanisms by which to derive the alternations observed in the Bondo-so Imperative without having to invoke the presence of floating features, as proposed by Hantgan & Davis (2012).

7.2 Imperfective stems

Another context that Hantgan & Davis (2012) deem somewhat problematic is the Imperfective stem. Formation of the Imperfective stem involves two suffixes following the root (an aspectual Imperfective suffix, and one of several suffixes marking person/number). We illustrate below that the alternations in these affixes follow transparently from the principles we have outlined and motivated above. In fact, we view the examples of the Imperfective stem formed from [ATR] roots in (15) and those formed from roots whose vowel is unspecified for this feature in (16) to be strongly in support of our analysis. These examples illustrate a combination of progressive harmonization via spreading but also reveal that the two suffixes following the root are structurally quite different from one another and thereby entail different alternations.

We propose that the Imperfective suffix vowel is underlyingly specified for the same features as the Imperative, namely V-Manner [open, ATR] (see Figure 12). This motivates the primary alternation between [a] and [o]. One alternant, [a], follows “lax” roots after the underlying featural specification of the suffix has been adjusted (via the removal of [ATR]) to satisfy surface well-formedness. The second alternant, [o], arises after “tense” roots due to [closed] spreading from the root vowel. We address the third vocalic alternant, [ɔ], below. While generally resulting in the same alternations as the Imperative, the Imperfective suffix differs in that it appears to behave structurally like other “weak” suffixes, such as the Perfective, that do not project a PWd.

We attribute the paradigmatic oddity of forms inflected for the third person plural to the fact that person/number suffixes are structurally higher than the Imperfective suffix in that they project a PWd; we proposed the same to be true of the Infinitive and Mediopassive suffixes. By virtue of being structurally higher, an [ATR] licensing constraint dictates the specification for this feature on all preceding vowels. Importantly, however, the data reveal that all person/number suffixes other than the third person plural are associated with [ATR] (like for the Infinitive); the third person plural is unspecified for this feature (like for the Mediopassive), resulting in [ɔ] in (15f). Again, because *[a̘] is not licensed on the surface, the Imperfective suffix is realized [a] in (16a–e).

We have illustrated that an analysis of Bondu-so VH within the PSM that appeals to licensing not only accounts for relatively straightforward cases of transparent harmonization but also accounts for those with more complex interactions between roots and suffixes where underlying featural specifications are obscured.

7.3 Moraic minimality

Thus far, we have set aside discussion of the alternations that arise in the formation of the Chaining (and Past) stem that result in [Ø]. We introduced above that in forming the Chaining stem, all roots whose vowel is unspecified for [ATR], regardless of whether they end in an obstruent or sonorant, surface with an epenthetic [-ɛ], as in (17f–j) and (18d–f). Obstruent-final roots whose vowel is specified for [ATR], like those in (17a–e), instead surface with an epenthetic [-i] while sonorant-final roots with an [ATR] vowel, like in (18a–c) instead require no epenthetic vowel.

We motivated epenthetic [-ɛ] and [-i] featurally in our PSM-style analysis, and in this section, our aim is to account for the third, null alternant. Given that this null outcome is limited to sonorant-final roots with an [ATR]-specified vowel, we would like to propose that this outcome relates to a well-formedness condition predicated on moraic minimality.

Given what we have observed in Bondu-so, we propose that root-final sonorants, by virtue of exhibiting V-Manner features, are licensed to receive [ATR] and do so via spreading from a root vowel specified for this feature. The presence of [ATR] on these segments, in turn, licenses the projection of a mora. This relates to the [-ɛ]/[-i]/[Ø] alternation in that once these coda sonorants project a mora, they contribute to the satisfaction of a bimoraic minimality condition in Bondu-so on prosodic word well-formedness. Roots ending with a moraic sonorant achieve bimoraicity, which accordingly precludes epenthesis. Such minimality requirements are common cross-linguistically (Hayes 1995). While preliminary, the perspectives that we offer here are generally in line with research exploring correlations between [ATR] and “tensed” sonorants found in Carnie (2002) for Irish and between [ATR] and fortis sonorants found more recently in Uchihara & Báez (2016) for Quiaviní Zapotec.

Root-final sonorants in Bondu-so that do not receive [ATR] from the root vowel fail to license a mora and therefore require epenthesis to achieve bimoraicity. Of course, additional research will be necessary to substantiate certain details of this proposal, particularly regarding any phonetic correlates that distinguish moraic sonorants from their non-moraic counterparts. Preliminary measurements of the Past stem, however, indicate that the length of [l] following a root with a “tense” vowel is slightly longer than that following a “lax” vowel.