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# The features and geometry of tone in Laal

Florian Lionnet

► To cite this version:

Florian Lionnet. The features and geometry of tone in Laal. Phonology, 2023, (First View), pp.1-42.
10.1017/S0952675723000040. hal-04232518

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Submitted on 8 Oct 2023

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# The features and geometry of tone in Laal

Florian Lionnet

Program in Linguistics, Princeton University, 1-S-19 Green Hall, Princeton, NJ, 08544, United States. E-mail: flionnet@princeton.edu

**Received:** 21 February 2022; **Revised:** 25 July 2022; **Accepted:** 30 August 2022

**Keywords:** tone, tonal features, feature geometry, tonal assimilation, floating feature

## Abstract

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.

## Contents

1. Introduction 2

2. Preliminary remarks on Laal 4

2.1 Language and data 4

2.2 Phonological sketch 4

3. Tone distribution and the exclusivity of M 7

4. M-lowering and the instability of M 9

4.1 Morphophonological M-lowering 9

4.2 Morphosyntactic M-lowering 10

4.2.1 M-lowering in transitive verbs 10

4.2.2 M-lowering in genitive constructions 14

4.2.3 M-lowering as inflectional morphology 17

4.3 Interim summary 21

5. Subtonal analysis 21

5.1 Subtonal features 21

5.2 Morphophonological M-lowering as [-raised] assimilation 22

5.3 Morphosyntactic M-lowering: floating [-raised] suffix 24

© The Author(s), 2023. Published by Cambridge University Press. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0), which permits unrestricted re-use, distribution and reproduction, provided the original article is properly cited.
<table><tbody><tr><td>5.4</td><td>Distributional constraint *MX/XM: bidirectional [-raised] assimilation</td><td>25</td></tr><tr><td>5.5</td><td>The case of the ventive suffix</td><td>25</td></tr><tr><td>5.6</td><td>The emergence of subtonal features and the ambiguity of M.</td><td>27</td></tr><tr><td><b>6.</b></td><td><b>Evidence for the tonal root node: full tone spread and deletion</b></td><td><b>29</b></td></tr><tr><td>6.1</td><td>Base pattern reduction under suffixation</td><td>29</td></tr><tr><td>6.2</td><td>Full-tone spread in replacive tone patterns</td><td>31</td></tr><tr><td>6.3</td><td>High Tone Spread in inalienable possessive morphophonology</td><td>33</td></tr><tr><td><b>7.</b></td><td><b>Alternatives</b></td><td><b>34</b></td></tr><tr><td>7.1</td><td>Tone-as-unit analysis</td><td>34</td></tr><tr><td>7.2</td><td>Mid as zero</td><td>36</td></tr><tr><td>7.3</td><td>Tone height as one gradient feature</td><td>37</td></tr><tr><td>7.4</td><td>Alternative subtonal analysis</td><td>37</td></tr><tr><td><b>8.</b></td><td><b>Conclusion</b></td><td><b>39</b></td></tr></tbody></table>

# 1. Introduction

While featural representations are well established for segments, proposals to extend them to tone (e.g. Wang 1967; Yip 1980, 1989; Clements 1983; Pulleyblank 1986; Snider 1999, 2020; Hyman 1993a) have met more scepticism. Various proposals have been made regarding the featural representation of tone (see McPherson 2016 for a recent overview). The most widely used system is that of Yip (1980), which makes use of two features: one ‘register’ feature [±upper], dividing the tone range into an upper and a lower register, and a secondary feature [±high] further subdividing each register into discrete tonal categories. The latter feature was renamed [±raised] by Pulleyblank (1986: 125) to avoid any confusion with the vocalic feature [±high]. The analysis of a four-tone height system cast in these featural representations is given in (1) below.

<table><thead><tr><th>(1)</th><th>Tone height</th><th>Possible transcription</th><th>[upper]</th><th>[raised]</th></tr></thead><tbody><tr><td>4</td><td></td><td>ă</td><td>+</td><td>+</td></tr><tr><td>3</td><td></td><td>á</td><td>+</td><td>-</td></tr><tr><td>2</td><td></td><td>ā</td><td>-</td><td>+</td></tr><tr><td>1</td><td></td><td>à</td><td>-</td><td>-</td></tr></tbody></table>

Other authors (Clements 1983; Hyman 1993b; Snider 1999, 2020) have proposed very similar systems with unary rather than binary features, e.g. Snider’s (1999; 2020) register features *h* and *l* (≈ [±upper]), and tonal features *H* and *L* (≈ [±raised]). These two kinds of systems are mostly equivalent (although they differ on one non-trivial point: the definition of the register feature(s), as we will see in §5.1). Snider (1999, 2020) further refines the featural representation of tone by proposing a geometry in which subtonal features are linked to a Tonal Root Node (TRN), which is itself associated with a Tone Bearing Unit (TBU), as shown in (2).
(2) *Geometry of tone* (Snider 2020: 23)

<figure><img src="image_3.png" /></figure>

Recently, authors such as Hyman (2010) and Clements et al. (2010) have argued that African tone systems are better represented with tonal primitives (e.g. H, M, L) than with features. The main arguments rest on the absence of parallelism between segmental and subtonal features, and can be summarised in the following four points:

(3) a. there is no evidence for subtonal natural classes;

b. there is no evidence for assimilation or dissimilation involving subtonal features;

c. since combinations of two subtonal features allow for the representation of a four-way contrast, subtonal features are not suited for three-tone languages, where the specification of the M tone is ambiguous;

d. a two-feature system allows for interactions between non-adjacent tones, for which there is no solid empirical argument.

The main goal of this paper is to bring additional evidence in favor of subtonal features. To this effect, I present the tone system of Laal, an under-documented language isolate of southern Chad with three contrastive tone heights. I argue that a representation of tone à la Snider (1999, 2020) as a tonal root node linked to two subtonal features offers a natural account of the tonology of Laal. The main empirical support for subtonal features comes from the mid tone, whose behaviour is otherwise difficult to account for in a unified manner. The puzzling tonal realisation of the ventive suffix also finds a straightforward explanation with subtonal features. In response to the criticisms listed in (3) above, I show that Laal has subtonal natural classes and assimilation patterns compatible with a featural approach, that the M tone in this three-tone system naturally lends itself to a non-ambiguous featural specification, and (iv) that the two non-adjacent tones H and L do interact and form a natural class. Laal is thus evidence that subtonal features are well-suited to account for three-tone systems.

Other tonal alternations attested in the morphophonology of Laal, such as replacive grammatical tone, high tone spread and full-tone deletion, involve operations targeting full tones, and not just subtonal features. This constitutes evidence for a hierarchical structure of tone similar to that in (2) above, where two subtonal features are linked to a tonal root node (TRN). The Laal facts thus show that tones, just like segments, can be either fully active (TRN activity), or partially active (subtonal feature activity). I also show that subtonal features can exist on their own just like (floating) segmental features.
The paper starts with background information on the Laal language and data sources (§2). The distribution and behaviour of the M tone are described in §3 and §4 respectively. I then propose a subtonal analysis of these facts in §5, and show in §5.5 that this analysis also accounts for the tonal behaviour of the ventive suffix. The emergent nature of subfeatures is discussed in §5.6. The inclusion of the Tonal Root Node in the proposed tone geometry is justified in §6 with the analysis of three other tonological processes: base tone pattern reduction upon suffixation, replacive grammatical tone in the gerund and passive suffixes and high tone spread with inalienable possessive suffixes. Alternatives are presented in §7 and shown to be less adequate than the subtonal analysis. Finally, §8 concludes.

## 2. Preliminary remarks on Laal

### 2.1. Language and data

Laal is a language isolate spoken by about 800 people in Gori and Damtar, two villages along the Chari river in southern Chad, as well as in urban centres such as Sarh and N’Djaména. Prior work on the language was undertaken in the 1970s by Pascal Boyeldieu, who published a preliminary description of the sound system (Boyeldieu 1977), as well as a description of the nominal and verbal systems (Boyeldieu 1982, 1987) which includes the first description of the M-lowering patterns described and analysed in this paper.

Unless explicitly stated, all the data presented in this paper come from my own fieldwork: about eighteen months between 2010 and 2020, with multiple speakers of various ages, both male and female, mostly in Gori, as part of a language documentation project funded by the DOBES (Documentation of Endangered Languages) program of the Volkswagen Foundation. Speaker participation and informed consent were obtained in accordance with IRB protocols #2011-03-3000 (University of California, Berkeley) and #10346 (Princeton University).

The data collected during the documentation project are archived and openly accessible as part of the DOBES collection in The Language Archive, hosted by the Max Planck Institute for Psycholinguistics in Nijmegen.<fnref n="1" /> Examples taken from archived text recordings are duly referenced. Examples without references are taken from my field notes or lexical database.

### 2.2. Phonological sketch

The 24 contrastive consonants and 12 contrastive vowel qualities of Laal are presented in (4). The stop inventory is reduced outside of the stem-initial position to one series of plain stops underspecified for voicing, realised as voiced word-internally, voiceless (and often unreleased) word-finally. The vowels /ia ua yo ya/ are most of the time realised as diphthongs, and are therefore systematically transcribed as such, but phonologically they are monomoraic vowels behaving exactly like /ɛ ɔ ɔ œ/ respectively. The low peripheral vowels /ia ua/ and the three front rounded vowels are attested only in

<footnote n="1">¹https://hdl.handle.net/1839/93472197-4462-489c-8cee-0d9a3587f3e5</footnote>
painful' → pāj-āl 'pain'), and the denominal suffix deriving nouns referring to ethnic or cultural characteristics (e.g. ndààm 'Ndam (village name)' → ndààm-ál 'characteristic of the Ndam people'). All other inflectional and derivational suffixes belong to stratum 2: alienable possessive suffixes, object suffixes, gerund, ventive, associative, medio-passive, and passive, all of which will be illustrated and discussed in the paper. This is summarised in Table 1. These strata are defined by different morphophonological processes, or the application of the same processes under different conditions – in particular the vowel harmony processes discussed below. Stratum 1 morphophonology is mostly irregular and unpredictable, in contrast to stratum-2 morphophonology, which is extremely regular and knows no exception.

<table><caption>Table 1: Laal suffixes by stratum</caption><thead><tr><th></th><th>Stratum 1</th><th>Stratum 2</th></tr></thead><tbody><tr><td>Noun base</td><td><ul><li>Number-marking suffixes</li><li>Denominal</li></ul></td><td><ul><li>Possessive suffixes</li></ul></td></tr><tr><td>Verb base</td><td><ul><li>Number-marking suffixes</li><li>Deverbal</li></ul></td><td><ul><li>Object suffixes</li><li>Ventive</li><li>Associative</li><li>Gerund</li><li>Passive</li><li>Medio-passive</li></ul></td></tr></tbody></table>

Three vowel harmony processes are attested in Laal: perseverative [+high] harmony, anticipatory [±low] harmony, and anticipatory rounding harmony, illustrated in (5), (6), and (7) respectively.

(5) [+high] harmony: $V_{\text{mid}} \rightarrow V_{\text{high}} / V_{\text{high}}$ —
$m\bar{\bar{\bar{i}}}$w ‘liver’ $m\bar{\bar{i}}$i\`w\`i\`r$ \text{‘my liver’}$ ($/\text{–}r\text{/ ‘my’} \rightarrow \text{–}r\text{)}^4$
mīlā ‘eye’ $m\bar{i}$līl$ \text{‘my eye’}$
mbūl ‘navel’ mbùlīl$ \text{‘my navel’}$

(6) Low harmony: $[-\text{high}] \rightarrow [\alpha \text{ low}] / [\alpha \text{ low}]$

a. [-low, +high] medio-passive /-íp/:
stem low → mid
ia → e $\dot{i}$áár ‘choose’ → $\dot{i}$ééríp$ \text{‘be chosen’}$
a → ə $m\bar{\bar{a}}$à ‘gather’ → $m\bar{\bar{a}}$íp$ \text{‘be gathered’}$
ua → o $ju\bar{\bar{a}}$ŋ ‘buy, sell’ → $j\bar{\bar{o}}$níp$ \text{‘buy from one another’}$

b. [-low, -high] /-\`r/ ‘my’: stem low → mid
ia → e piáár ‘shin’ → péér\`\`\`\`r$ \text{‘my shin’}$
a → ə $m\bar{\bar{a}}$l ‘tongue’ → $m\bar{\bar{a}}$l\`\`\`l$ \text{‘my tongue’}$
ua → o buàg ‘chin’ → $b\bar{\bar{o}}$g\`\`\`\`r$ \text{‘my chin’}$

<footnote n="4">⁴The final /r/ of /-Vr/ suffixes is realised as [l] when following a stem ending with /l/.</footnote>
c. [+low] /-àr~àn/ 'it (obj)’: stem mid → low
e → ia léérí ‘roll’ → liáár-àn ‘roll it’
ə → a cər ‘want’ → càr-àr ‘want it’
o → ua sór ‘find’ → suár-àr ‘find it’

(7) *Rounding Harmony*: [-round] → [+round] / __ [+round]<sup>5</sup>
e.g. /-ò ~ -òn/ ‘her’ (→ -ù ~ -ùn, [+high] harmony)

<table><tr><td>i → y</td><td>pīg</td><td>'tie'</td><td>pỳgùn</td><td>'tie her'</td></tr><tr><td>e → yo</td><td>léér</td><td>'wrap'</td><td>lyóóròn</td><td>'wrap her'</td></tr><tr><td>i → u</td><td>pír</td><td>'catch'</td><td>púrù</td><td>'catch her'</td></tr><tr><td>ə → o</td><td>lər</td><td>'wait'</td><td>lòrò</td><td>'wait for her'</td></tr></table>

Finally, Laal has three contrastive tone heights: high (H), mid (M), and low (L), illustrated in the minimal triplet in (8) below.

(8) kúmá ‘type of basket’
kūmā ‘to hide’
kùmà ‘medicine, medication’

The tone-bearing unit is the mora, as shown by the fact that bitonal patterns are only found on CVV and CVR syllables (where R stands for sonorant), and the only case of a tritonal pattern attested on a monosyllabic stem is *bôôr* ‘pigeon sp.’, a trimoraic CVVR syllable.<fnref n="6" /> As is shown in the next section, the three tones can combine into a limited number of stem-level patterns. The distribution of tones as well as aspects of the morphotonology of the language point to a marked status of the M tone, as compared to both H and L. This is the object of the next two sections.

### 3. Tone distribution and the exclusivity of M

Stem-level tone patterns in Laal are tritonal at most.<fnref n="7" /> All three single-tone patterns and all combinations of H and L (HL, LH, HLH, LHL) are attested, as shown in Table 2.<fnref n="8" /> All are also attested as contours when associated with monosyllabic stems, except LHL, likely an accidental gap (tritonal patterns are rare in general, and can be realised as contours only on trimoraic syllables, which are much less frequent than mono- and bimoraic ones).

The tone patterns in Table 2 represent 96% of all stems. The remaining 4% consists of tri- and tetrasyllabic stems (2%) – exceptional and ignored here – as well as a few bitonal patterns including a M tone: 24 HM (1%), 11 MH (0.5%), and 11 LM (0.5%). ML is strictly unattested. These include 17 HM and five MH native function words.

<footnote n="5">⁵Rounding harmony applies unconditionally only in stratum-2 morphophonology (mostly verbal morphology). In stratum 1 (mostly number marking morphology on nouns and verbs), it applies under very strict conditions: the target vowel must be in the vicinity of a labial consonant, and the trigger and target vowels must be of equal height and [front] specifications (cf. Lionnet 2017).</footnote>

<footnote n="6">⁶There are only two exceptions in native vocabulary: *pi* ‘flower’ and *juāb* ‘to walk fast’ – five with the three recent loanwords *süg* ‘market’ (< Chadian Arabic /su-g/ [sù·k]), *tīg* (< French *touque*) and *big* ‘pen, pencil’ (<French *bic*).</footnote>

<footnote n="7">⁷The only few exceptions are found with lexical items that are exceptional in other respects, including ones that are longer than two syllables or that violate phonotactic requirements otherwise strongly enforced in the language.</footnote>

<footnote n="8">⁸The information in Table 2 is taken from my lexical database, collected in the field between 2010 and 2020, which contains 2,695 mono- and disyllabic stems.</footnote>
<table><caption>Table 2: Regular tone patterns on mono- and disyllabic stems</caption><thead><tr><th>Tone Pattern</th><th>Number of stems</th><th>%</th></tr></thead><tbody><tr><td>H</td><td>726</td><td>27</td></tr><tr><td>M</td><td>599</td><td>22</td></tr><tr><td>L</td><td>548</td><td>20</td></tr><tr><td>LH</td><td>486</td><td>18</td></tr><tr><td>HL</td><td>216</td><td>8</td></tr><tr><td>LHL</td><td>16</td><td>1</td></tr><tr><td>HLH</td><td>14</td><td>1</td></tr><tr><td>Total</td><td>2,605</td><td>96%</td></tr><tr><td>3- and 4-syllable stems</td><td>50</td><td>2</td></tr><tr><td>MX/XM patterns</td><td>46</td><td>2</td></tr><tr><td>Total stems</td><td>2,701</td><td>100%</td></tr></tbody></table>

Abstracting away from variants and forms inflected for gender and/or number, this number actually reduces to six HM and two MH function words, listed in (9).<fnref n="9" />

(9) a. *HM function words*

<table><tr><td>wáã, PL wīī</td><td>ITIVE ('go VERB')</td></tr><tr><td>náã, PL nīī</td><td>PROSPECTIVE ITIVE ('will go VERB')</td></tr><tr><td>máã, PL mīī</td><td>INTENTIONAL ('intend to VERB')</td></tr><tr><td>jáã</td><td>PURPOSIVE ('for'; see fn. 9)</td></tr><tr><td>juánã</td><td>DEMONSTRATIVE (see fn. 9)</td></tr><tr><td>séélē</td><td>'when'</td></tr></table>

b. *MH function words*

<table><tr><td>tāá, PL tīí</td><td>IMPERFECTIVE (variant /tēé/)</td></tr><tr><td>jāá ~ jālá</td><td>SIMILATIVE ('like')</td></tr></table>

The remaining HM and MH stems, as well as all LM stems, are all nouns borrowed from neighbouring three-tone languages where tone patterns involving M are attested, e.g. *tijāŋgō* ‘Tockus sp., bird sp.’ (cf. Sar *tāýōng*), *kēsé* ‘bow, arrow’ (cf. Barma *kēsé*), *tèmē* ‘sieve’ (cf. Barma *tèmē*).<fnref n="10" />

Apart from these exceptional function items and loanwords, it can be concluded that the Mid tone in Laal is exclusive: if it is present in a stem-level pattern, it must be the only tone of that pattern (*MX/XM).

<footnote n="9">⁹ The forms of the purposive and demonstrative are /jáã/ and /juánã/ respectively in the masculine singular, /jīī/ and /júnū/ in the feminine singular, /máã/ and /muánã/ in the neuter singular, /jáã/ and /juánã/ in the neuter plural, /jīī/ and /júnū/ for all plurals and the abstract singular (this is a simplified description; see Lionnet 2021 for more detail on the gender system).</footnote>

<footnote n="10">¹⁰ Sar data are taken from Palayer (1992), Barma data from Keegan & Idris (2016).</footnote>
## 4. M-lowering and the instability of M

Not only is M exclusive, it is also unstable. Specifically, M is systematically changed to L in various morphophonological (§4.1) and morphosyntactic (§4.2) contexts.

### 4.1. Morphophonological M-lowering

Whenever a non-M-toned suffix is added to a M-toned root, the M tone is systematically changed to L. This lowering applies to avoid creating a complex stem-level tone pattern involving a M tone, i.e. to comply with the phonotactic constraint described above. This is illustrated in (10) with three suffixes carrying the three most frequent suffixal tone patterns: H, L, and LH.<fnref n="11" />

<table><tr><td>(10)</td><td>a. /dāg-án/</td><td>dàgón</td><td>'drag me'</td></tr><tr><td></td><td>b. /dāg-àn/</td><td>dàgàn</td><td>'drag it'</td></tr><tr><td></td><td>c. /dāg-nǔŋ/</td><td>dògnǔŋ</td><td>'drag you (PL)'</td></tr></table>

As seen, the M tone of the verb root is systematically changed to L, irrespective of the nature of the following tone: H in (10a), L in (10b), LH in (10c). Only M tones are affected, as shown by the stability of H- and L-toned roots in (11).

<table><tr><td>(11)</td><td>a. /kár-ón/</td><td>kórón</td><td>'put me'</td></tr><tr><td></td><td>/kár-àn/</td><td>káràn</td><td>'put it'</td></tr><tr><td></td><td>/kár-nǔŋ/</td><td>kórnǔŋ</td><td>'put you (PL)'</td></tr><tr><td></td><td>b. /jàr-ón/</td><td>jàrón</td><td>'slice/sacrifice me'</td></tr><tr><td></td><td>/jàr-àn/</td><td>jàràn</td><td>'slice/sacrifice it'</td></tr><tr><td></td><td>/jàr-nǔŋ/</td><td>jòrnǔŋ</td><td>'slice/sacrifice you (PL)'</td></tr></table>

M-lowering applies with all stratum-2 suffixes (except the gerund and passive suffixes, whose tone is replacive; see §6.2): object suffixes as in all the above examples, but also inalienable possessive suffixes on nouns (both H-toned as in (12a) and L-toned as in (12b), associative as in (13), mediopassive as in (15), and ventive as in (14)).<fnref n="12" />

<table><tr><td>(12)</td><td>a. /bāg-rúŋ/</td><td>bàgrúŋ</td><td>'your (PL) shoulder'</td></tr><tr><td></td><td>/gōm-rú/</td><td>gòmrú</td><td>'our (EXCL) voice'</td></tr><tr><td></td><td>/nīīnī-ráŋ</td><td>nìnráŋ</td><td>'our (INCL) woman/wife'<fnref n="13" /></td></tr><tr><td></td><td>b. /bāg-àr/</td><td>bàgàr</td><td>'my shoulder'</td></tr><tr><td></td><td>/gōm-ò/</td><td>gòmò</td><td>'her voice'</td></tr><tr><td></td><td>/nīīnī-àr</td><td>nìinàr</td><td>'his wife'</td></tr></table>

<table><tr><td>(13)</td><td>a. /būl-V̄/</td><td>bùlú</td><td>'open with'</td></tr><tr><td></td><td>b. /pīg-V̄/</td><td>pīgí</td><td>'tie with'</td></tr><tr><td></td><td>c. /dīīn-V̄/</td><td>dīiní</td><td>'swim with'</td></tr></table>

<footnote n="11">¹¹The last attested suffixal pattern is M, found only in the passive suffix, whose tone is replacive, as we will see in §6.</footnote>

<footnote n="12">¹²The ventive and associative suffixes consist of a copy of the root vowel, represented with a capital V. The ventive suffix is tonally specified as [—raised], which explains why it causes M-lowering, as is discussed more in detail in §5.5.</footnote>

<footnote n="13">¹³The stem initial vowel shortening in *nínáŋ* (instead of *nìinráŋ*) is regular, and applies in to comply with a stratum-1 phonotactic constraint against *VVCC* sequences, i.e. against non-final CVVC syllables.</footnote>
(14) a. /būl-V[-r]/ bùlù 'open (toward speaker / until now)'
b. /pīg-V[-r]/ pìgì 'tie (toward speaker / until now)'
c. /dīn-V[-r]/ dīnì 'swim (toward speaker / until now)’

(15) a. /būl-íny/ bùlíny 'be open'
b. /pīg-íny/ pìgíny 'be tied'

Note that M-lowering applies with both transitive and intransitive verbs (e.g. ‘swim’ in (13c) and (14c), and with suffixes that are not related to transitivity, such as the associative and ventive. M-lowering is thus not related to transitivity or argument structure, or in general to any morphosyntactic category. It is a general phonological operation that applies without exception in stratum-2 morphophonology.

As mentioned in the introduction, stratum 1 morphophonology is complex and mostly irregular, including in its tonal effects. Suffixation of a number-marking suffix (by far the most numerous stratum-1 suffixes) onto a M-toned root does not always result in lowering of the M to L. Out of 208 nouns that are M-toned in the singular or in the plural, this M pattern corresponds to an L-initial pattern (L or LH) in the other number category in 143 cases (69%; e.g. /kòòg/, PL /kuāg-mī/ ‘bone’, or /siāāg/, PL /sèèg-ú/ ‘milk’), to a M pattern (i.e. no tone change) in 36 cases (17%; /gār-āl/, PL /gār-tī/ ‘Acacia spp.’), and to a H pattern in 29 cases (14%; e.g. /kūr-ā/, PL /kúr-ú/ ‘stick’, or /wúl-ú/, PL /wūl-māny/ ‘Kigelia africana, tree sp.’). That is, despite the relative unpredictability of the tonal alternations involved, no MX or XM pattern is ever created as a result of number-marking (and more generally stratum-1) suffixation. Furthermore, The expected M~L alternation is found in over two-thirds of all cases, whereas the unexpected M~H alternation accounts for only 14%.

## 4.2. Morphosyntactic M-lowering

M-lowering is also attested in two morphosyntactic contexts where it does not appear to be an effect of the *MX/XM constraint: on M-toned transitive verbs followed by an in-situ object (§4.2.1), and on the M-toned head of a genitive construction (§4.2.2).

### 4.2.1. M-lowering in transitive verbs

A M-toned transitive verb undergoes M-lowering whenever its syntactic object is present in *situ* – i.e. neither elided nor extracted. This is shown in the three examples in (16).<fnref n="14" />

(16) a. **já tō** vs. **já tò** kúdál
I carry
‘I carry (it).’
I carry(M>L) stone
‘I carry a stone.’

b. **já nāg** vs. **já nàg** tāā
I eat
‘I eat (it).’
I eat(M>L) fish
‘I eat fish.’

<footnote n="14">¹⁴ Aspect and modality are marked with preverbal particles. Verbs unmarked for aspect or modality have a wide range of possible interpretations, and will be translated either as present or past, depending on context and on the translation given by language consultants.</footnote>
<table><tr><td>c.</td><td>já jīrā</td><td>vs.</td><td>já jìrà</td><td>guàmàn</td></tr><tr><td></td><td>I hear</td><td></td><td>I hear(M&gt;L) your.voice</td><td></td></tr><tr><td></td><td>'I hear (it).'</td><td></td><td>'I hear your voice.'</td><td></td></tr></table>

Only M-toned verbs are affected. H, L, LH, and HL verbs (the other four attested tone patterns on verbs) are all realised with their underlying tone in the same context, as shown in (17).

(17) a. *H*: kár *put*
    já **kár** ndiáw bó sàndùg
    I put knife on trunk
    ‘I put a/the knife on a/the trunk.’

b. *L*: jàr ‘slice’
    já **jàr** tuààr
    I slice chicken
    ‘I cut the chicken’s throat.’

c. *LH*: jùgár ‘shake’
    à **jùgár** jāān
    he shake his.body
    ‘He is fidgety.’

d. *HL*: múrì ‘run (PL)’<fnref n="15" />
    ì **múrì** gààm
    they.M/F run:PL dance.sp
    ‘They did the funeral dance.’

As shown in (16), M-lowering occurs irrespective of the tone of the following word: H (16a), M (16b) or L (16c). The following examples show that it is not caused by the preceding tone either.

(18) a. náár **tō**
    his.mother carry
    ‘His mother carried (it).’

vs.

náár **tò**
    his.mother carry(M&gt;L) stone
    ‘His mother carried a stone.’

b. nīīnī **tō**
    woman carry
    ‘The woman carried (it).’

vs.

nīīnī **tò**
    woman carry(M&gt;L) stone
    ‘The woman carried a stone.’

c. bààr **tō**
    his.father carry
    ‘His father carried (it).’

vs.

bààr **tò**
    his.father carry(M&gt;L) stone
    ‘His father carried a stone.’

M-Lowering is attested both in matrix clauses, as in (16)–(18), and in subordinate clauses, as in (19).

<footnote n="15">¹⁵The intransitive verb /múr/, /PL/múri/ ‘to run (away)’ can be used transitively to mean ‘to dance (specifically the funeral dance)’, or ‘to drive (a vehicle)’.</footnote>
(19) in bílá mí Kábó mí tò kúdál
she say (say) that Kabo QUOT.EV carry(M>L) stone
‘She said that Kabo carried a stone.’

It occurs in all clause types: affirmative as in (16)–(18), negative as in (20a) or interrogative as in (20b).

(20) a. já tò kúdál wó
you.SG carry(M>L) stone NEG
‘I did not carry a stone.’

b. ò tò kúdál à
you.SG carry(M>L) stone Q
‘Did you carry a stone?’

Finally, it also occurs with all TAM markers combining with the base form of the verb (and not the gerund, cf. §4.2.3), e.g. habitual *kó* in (21).

(21) à kò tò kúdúr
he HAB carry(M>L) stone:PL
‘He usually carries stones.’

It is attested with nominal objects, as illustrated in (16), (18) and (21), but also with wh-objects, as shown in (22).

(22) jààn jìrà jè
bush know(M>L) who
‘Who does the bush know?’ (proverb)

It is also attested with gerund complement clauses, which can be considered nom-
inalised clauses acting as argument of the main verb, as shown in (23a), where cār
‘want’ is realised with a L tone, just as it is in (23b).<fnref n="16" />

(23) a. já còr kàrà páátī niìn-ìr
I want(M>L) do:GER wedding+CON woman-my
‘I want to organise my wife’s wedding ceremony.’ (110612-AK1: 84)

b. já còr cǎn dāā
I want(M>L) child+CON your
‘I want your child.’ (110612-AK1: 21)

As seen, cɔ̄r ‘want’ undergoes M-lowering when followed by a gerund complement clause (23a) as well as by a nominal object (23b). M-lowering is not triggered, however, by a following embedded clause introduced by a complementiser, as shown in (24).

<footnote n="16">¹⁶The connective (CON) that appears in (23a) is a function word used for noun modification with any type of modifier: noun, prepositional phrase, adverb, relative clause, alienable possessive markers, etc. The connective agrees in gender and number with the head noun: /já/ = masculine singular, /ji/ = feminine singular, /má/ = neuter singular, /já/ = neutral plural, /jí/ = all plurals, abstract singular. The connective has a H floating tone allomorph, which is realised on the last mora of the preceding word, creating a contour if this mora is associated with a M or H tone. This post-lexical contour is unrestricted, i.e. it is subject neither to the limit of one tone per mora nor to the \*MX/XM constraint, e.g. /sū H nīīr/ = [sū nīīr] (water CON be hot) ‘hot water’.</footnote>
(24) irí cōr mí *absolument* í míni irí pāāl kán
they.M/F.IND want (say)that absolutely [Fr.] they INT.PL take:GER village DEF
‘They are determined to conquer the village.’ (170703-KN2: 709)

M-lowering applies only if the syntactic object is present *in situ* (but not necessarily
immediately after the verb, as we will see in §4.2.3). Whenever the object is not in its
original post-verbal position, there is no M-lowering. This is the case, for example,
when the object is understood or elided, as with the verb jāg ‘eat’ in (25) (see also
(16)).

(25) ò sór nàr biàár ò jāg
you find little tilapia you eat
‘You find a little tilapia and you eat [it].’ (121120-09-OK1: 164)

It is also the case when the object is topicalised, as with * jāg* ‘eat’ in (26) (also *jīrā*
‘know’ in (28a)), or relativised, as *juāŋ* ‘to buy’ in (27).<fnref n="17" />

(26) tuààr ↗ sárú ↗ mōŋ ↗ [jí dāŋ]TOP jí **pāg** wó
chicken **LIST** tortoise **LIST** crocodile **LIST** CON.A ANAPH I.F eat NEG
‘Chicken, tortoise, crocodile, [all that]TOP, I don’t eat.’ (120322-FN1)

(27) já jìrà ound mīrā yá à juāŋ
I.M know(M>L) head:CSTR cattle:PL CON:N.PL he buy
‘I know how many head of cattle he bought.’ (lit. ‘I know the heads of cattle
that he bought’; 140402-028-HN1)

An adverb or prepositional phrase does not trigger M-lowering on the immediately
preceding transitive verb with an elided object, as shown with jīrā ‘know’ in (28a) and
jāg ‘pour’ in (29a). Compare with similar clauses with an in-situ object in (28b) and
(29b).

(28) a. jèw cán nūŋ jí jīrā tál wó
language Sar TOP I.F know well NEG
‘The Sar language, I don’t speak [it] well.’ (120405-04-AK3: 70)

b. já jìrà máánà nìrí
I.M know(M>L) history their
‘I know their history.’ (170703-KN2: 278)

(29) a. wógàd jí àn míin gàná ò suám ò **jāg** jà té
time **CON** it be.dry then you.SG take you.SG pour/put **LOC** on.ground
‘When it [the salt loaf] is dry, you take [it] and you put [it] down on the
ground.’ (120322-FN1: 02)

b. ßà jó dā ò jàg tílá jà té
for what firstly you pour(M>L) sand LOC on.ground
‘Why do you put sand on the ground?’ (120322-FN1: 60)

<footnote n="17">¹⁷The symbol ↗ represents a pitch rise used as a list coordination marker.</footnote>
The post-verbal noun phrase must be the syntactic object of the verb in order to
trigger M-lowering. This can clearly be seen when comparing post-verbal objects with
locative nouns used as adjuncts, e.g. *jààn*, which translates as ‘bush’, as in (22) above,
or ‘in the bush’, as in (30a). In the latter case, it does not trigger M-lowering on the pre-
ceding verb. The same verb does undergo M-lowering, however, when the following
noun is its object, as in (30b).

(30) a. *já tāār* *jààn*
I hunt bush
‘I hunt in the bush.’

b. *já tààr* *juánpá*
I hunt(M>L) elephants
‘I hunt elephants.’

Finally, M-lowering is not triggered by a dative pronoun immediately following a verb whose object is elided or extracted. For example, the third person neuter singular *nàná* ‘to it’ in (31) does not trigger M-lowering on the immediately preceding verb *pīg* ‘to tie’.

(31) [Context: Lion, a folktale character, decides to attach a shell filled with ashes to Hare's tail in order to be able to follow Hare's tracks; the storyteller addresses Lion in the second person, as is frequent in folktales.]

... ò **pīg** nàná jà tìmàn
you tie to.it **LOC** its.tail

‘... you tie [it] (=the shell) to its (=Hare’s) tale.’ (lit. ‘you tie [it] to it (=Hare) at its (=Hare’s) tail’; 120322-AK3: 74)

To summarise, M-lowering targets M-toned transitive verbs whose syntactic object is present *in situ*.

4.2.2. M-lowering in genitive constructions

Morphosyntactic M-lowering is not limited to the verb phrase. It also applies in the noun phrase, specifically to the M-toned head of a genitive construction. What I call ‘genitive construction’ is the direct modification of a noun by a noun or noun phrase in apposition, expressing a form of intrinsic relation between the two entities referred to by the modified and modifying elements, including but not limited to inalienable possession (cf. Boyeldieu 1987 for more detail). The genitive construction is head-initial and, as we will see, head-marked (at least for M-toned head nouns). The marking of the genitive relation on the head noun is what Creissels (2009, 2018: 724–733) calls ‘construct form’. In Laal, only M-toned nouns have a dedicated construct form, marked by M-lowering, as shown in (32).

(32) a. *dōrūm* ‘rope’
**dòrùm** hól
rope(M>L) plant.sp
‘rope made of plant sp.’
b. mīlā ‘eye, point’

mìlà sōōl
point(M>L) spear

‘spear point’

c. pūm ‘oil, fat’

pùm mèrìm
fat(M>L) animal

‘animal fat’

The examples in (33) show that only M-toned nouns undergo any tone change when heading a genitive construction. In other words, non-M-toned nouns do not have a dedicated construct form.

(33) a. *H*: hóy ‘shells’

hóy jūūrū
shells peanuts

‘peanut shells’

b. *L*: jàw ‘house’

pàw ndíí
house bird

‘bird’s nest’

c. *LH*: gàáw ‘wing’

gàáw ndíí
wing bird

‘bird’s wing’

There are three pieces of evidence showing that the genitive construction has syntactic status and is not simply a case of noun compounding. First, the genitive complement may be pronominalised, as in (34).<fnref n="18" />

(34) a. *jàw* ndíí
*house bird*
‘*bird’s nest*’

→

*nàw* nàná
*house its*
‘*its nest*’

b. wán mòl
boule pearl.millet
‘boule made of pearl millet’

→

wán nàná
boule its
‘boule made of it’

The genitive complement may also be a syntactically complex noun phrase, as in (35), where *jēn* (lowered to *jèn*) ‘body’ is the head and *căn nīīnī kán wùrù* ‘the girl’s family’ the complement.

<footnote n="18">¹⁸In (34b), wàn is a dough-like food made from millet or sorghum flour. It is served in a hemispheric shape, hence its local French name, boule (lit. ‘ball’).</footnote>
(35) kí jèn [[[ cǎn nīnī ] kán ] wùr-ù ]_NP

to body(M>L) child+CON woman DEF family-her

‘to the young woman’s family’ (110612-AK1: 18)

(lit. ‘to (kí jèn) the young woman (cǎn nīnī kán) her family (wùrù)’)

Finally, as shown in (36), there is no M-lowering in Noun-Noun compounds, which are not frequent in Laal, and are often fossilised and opaque (the symbol + is used to separate the individual stems making up each compound; see §5.2 for further discussion and (56) for more examples).

(36) mōō+gà+díígí ‘hippopotamus’ (hippopotamus+?+?)
wār+biig ‘bat’ (?+shellfish?)
ŋā+píírá ‘skink (PL)’ (?+?)

Exactly as we observed in the case of M-toned verbs, M-lowering on nouns is not attested in any other context. A M-toned noun keeps its M tone when modified by a connective construction, as seen in (37). The connective construction (noun + connective + modifier) is used to modify nouns with any type of modifier: noun (phrase), adverb, relative clause, etc.

(37) miān má dōŋ
road CON be.long
‘long road’

M-lowering is not triggered by a modifying numeral, as shown in (38).

(38) dōrūm bìdíl / wūrā māā
rope one men three
‘one rope’ / ‘three men’

Determiners (all post-nominal) do not trigger M-lowering either, as can be seen with the definite, indefinite, and partitive indefinite (‘one of…’) markers in (39).

(39) a. nīnī kán jíní
woman DET come
‘The woman came.’

b. nō jàn jíní cuàr-á
person INDF.M.SG come look.for-you(SG)
‘Someone came looking for you.’ (140329-34-HN1)

c. nō jánàn jíní cuàr-á
person INDF.PART.M.SG come look.for-you(SG)
‘One of the people came looking for you.’ (140329-36-HN1)

Focus and topic markers do not cause M-lowering on a preceding M-toned noun, as shown in 40 with the focus marker jì (40a), the topic marker muǎŋ (40b), and the contrastive topic marker lē (40c).
(40) a. **wūrā** jì mí tēé kí oundī jinān jì mí tēé kí
men FOC.PL QUOT.EV IPFV do.PL or women FOC.PL QUOT.EV IPFV do.PL
'[He is asking:] was it the men who used to do [this job], or the women.'
(120409-AK3[HN1]: 152)

b. ngiāāl muāŋ èènón ná jíní ná pìr-ì nā gòò
hyena TOP.N.SG (at)night PROS come PROS catch-GER.TR DAT:you(SG) goat
'(As for) the hyena, at night it will come and snatch a goat from you.'
(121120-OK1: 33)

c. nīnī lē íny óá miàdál
woman TOP.CONTR sit on tree
'The woman, on the other hand, sits on the tree.' (120322-HN1: 88)

Finally, M-lowering is not triggered by a following adverb, e.g. bìlà ‘only’ in (41a),
kàw ‘too, also’ in (41b), or the negative marker wó in (41c).<fnref n="19" />

(41) a. [in] tāá tùù siāāg bìlà
she IPFV suck:GER.TR milk only
'She was still only suckling.' (120405-4-AK3: 59)

b. mālā ków diààn
mala too there
'There is also (a tradition called) mālā.' (120331-DK4-160)

c. àn ná sèè nō wó
it PROS kill:GER.TR person NEG
'It will not kill anyone.' (lit. 'it will not kill a person'; 120321-02-AK3: 11)

In sum, M-lowering affects the M-toned head of a genitive construction.

4.2.3. M-lowering as inflectional morphology

Morphophonological M-lowering seems at first sight to be analysable as a syntactically
conditioned phonological alternation: in certain specific syntactic contexts – transitive
verb followed by its object, genitive head followed by its complement – M is changed
to L. I show in this section that this is not the correct analysis. I argue that these two
cases of morphosyntactic M-lowering are best analysed as head-marking inflectional
morphology, i.e. specific forms of verbs and nouns exponing a specific morphosyntac-
tic feature – in this case, the presence of a complement *in situ*: object of the transitive
verb, genitive complement in a genitive construction, i.e. a form of non-extraction
marking (cf. Lionnet 2015).<fnref n="20" />

<footnote n="19">¹⁹Locative predication, as in (41b), is direct in Laal, and requires neither a verb not an overt copula: /mālā ków Ø diààn/
= mālā also [is] there.</footnote>

<footnote n="20">²⁰A detailed syntactic analysis of the genitive construction is beyond the scope of the present paper. The noteworthy
parallel with transitive verb + object constructions, already noted by Boyeldieu (1987: 84), suggests parallel structures,
which is what underlies my choice of treating them both as head + complement structures. If a more thorough study of the
syntactic properties of the genitive construction were to show otherwise, it would not radically change the analysis proposed
here: the inflectional category expressed by M-lowering on a genitive head would simply be different from that expressed
by the same M-lowering on a transitive verb.</footnote>
Two arguments can be put forth in favour of an inflectional analysis of M-lowering on transitive verbs: adjacency, and morphological systematicity.<fnref n="21" />

Surface adjacency is not required between the verb and its object for M-lowering to occur. Indeed, the dative complement or adjunct frequently occurs before the object (this is its preferred position, if it is not too long), as shown in (42b). When it is pronominal, it obligatorily follows the verb, i.e. intervenes between the verb and its object, as in (43).

(42) a. à juàŋ/*juāŋ [sààb bìdíl]_{OBJ} [kí nīīnī]_{DAT}
he buy(M>L) cloth one for woman

‘He buys/bought one piece of fabric for the woman.’ (Boyeldieu 1982: 153)

b. à juàŋ/*juāŋ [kí nīīnī]_{DAT} [sààb bìdíl]_{OBJ}
he buy(M>L) for woman cloth one

‘He buys/bought the woman one piece of fabric.’ (Boyeldieu 1982: 153)

(43) a. à juàŋ/*juāŋ [nùg]_{DAT} [sààb bìdíl]_{OBJ}
he buy(M>L) DAT:3F.SG cloth one

‘He buys/bought her one piece of fabric.’

b. kùnú jàg/*jāg [nàná]_{DAT} [jámdéd]_{OBJ}
leopard pour(M>L) DAT:3N.SG bit

‘The leopard put the bit in its mouth. (lit. “leopard poured to.it the bit”; 121120-OK1: 159)

The second argument is paradigmatic systematicity: M-lowering is indeed only one of two morphological exponents of this inflectional category, the second one being found with the gerund form. The gerund is a nominalised form of the verb which can be used as an argument as in (44a). It is required after certain aspectual and modal markers: imperfective tāá/tíí~tēé, prospective ná/ní, itive wáā/wíí, prospective-itive náā/níí, injunctive-itive màá/míí, counterfactual mìná/mìní, and intentional mìnà/mínì (all are number-sensitive: SG/PL). This use is illustrated with the prospective marker ná in (44b). The gerund has two forms: one that is homophonous with the simple form of the verb, used when there is no overt object in *situ*, as in (44a-i) and (44b-i), and one which is marked with a suffix and used only with transitive verbs followed by an *in-situ* object as in (44a-ii) and (44b-ii). The marked form of the gerund is used in exactly the same context as M-lowering: this parallelism is briefly illustrated in (44b) and (44c), repeated from (16b).

(44) a. i. jāg pāj
eat(:GER) be.difficult
‘Eating is difficult.’

ii. jàg-à tāā pāj
eat-GER.TR fish be.difficult
‘Eating fish is difficult.’

<footnote n="21">²¹ Cf. Crysmann 2004, 2005, 2011 for similar arguments in favor of an inflectional analysis of similar facts in Hausa.</footnote>
b. i. **já** ná **nāg**
I PROS eat(:GER)
'I will eat (it).'

ii. **já** ná **ŋàg-à** tāā
I PROS eat-GER.TR fish
'I will eat fish.'

c. i. **já** **nāg**
I eat
'I eat (it).'

ii. **já** **nàg** tāā
I eat(M>L) fish
'I eat fish.'

This form is derived by the addition of the suffix /-V<sup>L</sup>/, which consists of an under-
specified vowel realised as a copy of the verb root’s final vowel, and a replacive L
tone that overwrites the underlying tone of the verb – i.e. all verb roots, irrespective
of their underlying tone, are realised with a L tone when combining with this suffix
(see §6.2 for more detail). Lexical tonal contrasts are thus completely neutralised in
the marked gerund form, as shown in the bottom-right quadrant of Table 3 (cf. §6 for
more detail).<sup>22</sup>

The marked form of the gerund is used with exactly the same function as M-
lowering: on transitive verbs with an overt object *in situ*. Just like M-lowering, it does
not occur when the object is topicalised (45) or relativised (46).

(45) [jí dāŋ]top mālā tēé cār/*càrà wó pār.
CON.A ANAPH mala IPFV want:GER/GER.TR NEG all

'Those things [I've just mentioned], the *mala* does not like any of them.'
(120331-DK4: 176)

(46) jí rāāg ná **ká**/*kàrà** nǔŋ
CON.A God PROS do:GER/GER.TR DAT:you(PL)

'what God will do to you (pl.)' (110612-AK1: 116)

It is not used when the verb is followed by an adjunct locative noun, as in (47a);
compare with the effect of an *in situ* object in (47b).

(47) a. já náá **tāār**/*tààr-à** jààn
I PROS.IT hunt:GER/-GER.TR bush

'I will go hunt in the bush.'

b. já náá **tààr-à**/*tāār** né
I PROS.IT hunt-GER.TR/GER elephant

'I will go hunt an elephant.'

Finally, like with M-lowering, the marked form of the gerund is used when a dative
complement or adjunct intervenes between the verb and the object, as shown in (48),
repeated from (40).

<footnote n="22"><sup>22</sup>With a subset of Ca(a) verbs, an [r] is epenthised between the root and the following suffix, e.g. 'já 'take', 'jà-r-à 'take (GER)'. This epenthesis occurs with all suffixes for this set of verbs – the only exception is ká 'do', for which r-epenthesis is not found with pronominal suffixes, e.g. kà-r-à 'do (GER), but ká-àn 'do it'.</footnote>
(48) ... ná jíní ná **pìr-ì/*pír** nā gòò
PROS come PROS catch-GER.TR/GER DAT:you(SG) goat
‘... [it] will come and snatch a goat from you.’ (121120-OK1: 33)

Both M-lowering and the /-V<sup>L</sup>/ suffix are thus exponents of the same inflectional category, in morphosyntactic complementary distribution: M-lowering on simple finite verbs (i.e. non-derived and not otherwise inflected), the suffix /-V<sup>L</sup>/ on gerunds. This is summarised in Table 3.

<table><caption>Table 3: Simple and gerund forms</caption><thead><tr><th></th><th>No object in situ</th><th>Object in situ</th></tr></thead><tbody><tr><td>Simple form:</td><td>Ø</td><td>M-lowering</td></tr><tr><td>H</td><td>kár 'put'</td><td>kár 'put +OBJ'</td></tr><tr><td>M</td><td>ŋāg 'eat'</td><td>ŋāg 'eat +OBJ'</td></tr><tr><td>L</td><td>jàr 'sacrifice'</td><td>jàr 'sacrifice +OBJ'</td></tr><tr><td>Gerund form:</td><td>Ø</td><td>/-V<sup>L</sup>/ suffix</td></tr><tr><td>H</td><td>kár 'put:GER'</td><td>kàr-à 'put:GER +OBJ'</td></tr><tr><td>M</td><td>ŋāg 'eat:GER'</td><td>ŋàg-à 'eat:GER +OBJ'</td></tr><tr><td>L</td><td>jàr 'sacrifice:GER'</td><td>jàr-à 'sacrifice:GER +OBJ'</td></tr></tbody></table>

As for M-lowering in the genitive construction, the same argument of paradigmatic systematicity can be used as evidence of its status as inflectional morphology. Indeed, there are ten nouns in Laal which have a specific construct form, usually obtained through truncation of the number marking suffix, and used in exactly the same context as M-lowering:

<table><thead><tr><th>(49)</th><th>Regular form</th><th>Construct form</th><th></th></tr></thead><tbody><tr><td></td><td>bír-ál</td><td>bír (~ bírál)</td><td>'pit (of fruit)'</td></tr><tr><td></td><td>bìn.mìn-án</td><td>bìn.mìn</td><td>'forehead'</td></tr><tr><td></td><td>jìn-án</td><td>jìn</td><td>'belly'</td></tr><tr><td></td><td>bàg-ál</td><td>bà (~ bàgál)</td><td>'head'</td></tr><tr><td></td><td>jāw-āl</td><td>jàw</td><td>'mouth, language'</td></tr><tr><td></td><td>mēē-l</td><td>mèè (~ mèèl)</td><td>'name'</td></tr><tr><td></td><td>jē-n</td><td>jèè (~ jèn)</td><td>'bottom'</td></tr><tr><td></td><td>jē-n</td><td>jèè (~ jèn)</td><td>'body'</td></tr><tr><td></td><td>nīnīnī</td><td>nīn</td><td>'woman, wife'</td></tr><tr><td></td><td>wúrá</td><td>wúr</td><td>'thing (PL)'</td></tr></tbody></table>

Consequently, M-lowering, both in the verb phrase and in the genitive construction, must be analysed as the morphological exponent of a morphosyntactic category. This category can be defined as “non-extraction marking” (or “presence of complement in situ”).
### 4.3. Interim summary

The three-tone system of Laal displays a number of distributional restrictions on the M tone that the H and L tones are exempt from. The M tone is exclusive, i.e. there is a strong constraint against stem-level tone patterns involving a M tone (*MX/XM, with a few exceptions among function words and recent loanwords). To avoid creating this banned structure, M tones followed by H- or L-toned suffixes are systematically changed to L. Additionally, generalised M-lowering is observed as the exponent of a morphosyntactic category (presence of a complement *in situ*) in two specific morphosyntactic environments, in the absence of any violation of *MX/XM. This raises at least the following five questions:

(50) a. Static distribution: why is there no MX or XM pattern?

b. Target: Why is only M affected by lowering, and not H?

c. Trigger: Why is M changed to L when followed by both L and H?

d. Alternation: Why is M changed to L and not to H?

e. Finally, is a unified account of all this possible?

I show in the next section that a subtonal analysis of the Laal tone system offers a unified, straightforward account of all these phenomena.

## 5. Subtonal analysis

### 5.1. Subtonal features

Using Pulleyblank's (1986: 125) version of Yip's (1980) two-feature model, I propose the following analysis of the Laal tone system:

(51) *Tone features*

<table><thead><tr><th></th><th>[upper]</th><th>[raised]</th></tr></thead><tbody><tr><th>H</th><td>+</td><td>-</td></tr><tr><th>M</th><td>-</td><td>+</td></tr><tr><th>L</th><td>-</td><td>-</td></tr></tbody></table>

Specifically, M is analysed as the higher tone within the lower register, i.e. [–upper, +raised], while the [+upper] register is limited to H, analysed as [+upper, –raised]. Missing from this system is the subtonal specification [+upper, +raised]. This gap is reminiscent of similar segmental gaps (i.e. unattested featural combinations) in phone-mic inventories, e.g. cross-linguistically frequent lack of a voiceless bilabial plosive or absence of front rounded vowels (cf. §5.6 for further discussion). This subtonal analysis will be justified in the following sections – in particular (i) the treatment of M as [–upper] and as the only [+raised] tone in the system, and (ii) the analysis of H as [–raised].

I further assume the tone geometry in (52), borrowed from Snider's (1999; 2020) Register Tier Theory.
(52) *Tone geometry* (after Snider 2020: 23)

<figure><img src="image_4.png" /></figure>

The two subtonal features [upper] and [raised] are on two separate tiers. They are linked to a Tonal Root Node (TRN), which is a representation of a ‘full’ tone, i.e. H, M or L. The TRN is in turn associated with the TBU, i.e., the mora in Laal. This representation allows for both feature spreading and ‘full tone’ (i.e. TRN) spreading, both of which are necessary to account for the tonology of Laal, as I show in this and the next section.

I do not adopt Snider’s features H, L, *h*, and *l* here. Indeed, while his two “tone features” H(igh) and L(ow) can be considered to be the exact equivalent of Pulleyblank’s (1986) [+raised] and [–raised] respectively (and Yip’s (1980) [+high] and [–high]), his two register features *h*(igh) and *l*(ow) are not equivalent to Yip and Pulleyblank’s register feature [±upper]. The latter is defined on purely paradigmatic grounds: [+upper] tones are realised within a higher register than [–upper] tones. In contrast, Snider’s *h* and *l* register features are defined in both paradigmatic and syntagmatic terms: they ‘effect a register shift *h* = higher and *l* = lower *relative to the preceding register setting*’ (Snider 2020: 25, emphasis mine; see also pp. 151–153). This definition allows Snider to account for downstep and upstep phenomena with register features. Since downstep is not at issue here, I prefer to adopt a purely paradigmatic definition of the register feature.

## 5.2. Morphophonological M-lowering as [–raised] assimilation

Within the subtonal feature system proposed in (51) above, I propose to analyse M-lowering as the result of one simple process: [–raised] agreement/assimilation, which applies in response to a stem-internal constraint against sequences of disagreeing [raised] features: *[*α* raised][*β* raised]$_{STEM}$. This straightforwardly accounts for morphophonological M-lowering, and explains (i) why only M is targeted – it is the only [+raised] tone, i.e., the only possible target of [–raised] assimilation – and (ii) why both H and L trigger it – they both carry the assimilating feature [–raised]. This is illustrated in (53) below, with assimilation/agreement formalised as [–raised] spreading. H- and L-toned suffixes are represented together, the only featural difference between them being the value of the [upper] feature, which plays no role in [–raised] assimilation. The features [upper] and [raised] are shortened to [u] and [r] respectively in autosegmental representations, for lack of space.
(53) /dāg-àn~-án/ → dàgàn ~ dàgán ‘drag it~him’

<figure><img src="image_5.png" /></figure>

This analysis also naturally accounts for the fact that neither L nor H is targeted by any tonal changes in the same context: they are both already [–raised] and therefore (i) they do not violate the *[α raised] [β raised]_STEM constraint when followed by a suffix carrying a [–raised] feature, and (ii) they are never targeted by [–raised] assimilation. This is shown in (54) and (55), where the root and suffix [–raised] features either stay as they are, or merge (depending on whether one wants to enforce an OCP-[RAISED] constraint within stems, which is not necessary in the present analysis).

(54) /kár-àn~-án/ → káràn ~ kárán ‘put it~him’

<figure><img src="image_6.png" /></figure>

(55) /jàr-àn~-án/ → jàràn ~ jàrán ‘sacrifice it~him’

<figure><img src="image_7.png" /></figure>

Evidence that the domain of application of this constraint is the stem rather than the phonological word comes from frozen nominal compounds. Compounding is not productive in present-day Laal, but 95 words in the lexicon can be identified as frozen compounds. In most cases, the elements of the compounds are not attested on their own, and cannot be ascribed a meaning anymore. They can only be identified as members of a compound because they occur in several words, and/or are marked for number separately (e.g. /mōō+gà+díígí/, PL /mùù-rí+gà+díígí/ ‘hippopotamus’, /gà+jàw/, PL /gà+jàw-ó/ ‘fish trap’, where the plural suffix /-o/ attaches to and triggers [±low] harmony on the second element of the compound only). If these frozen compounds were to be analysed as one-stem words, most would violate one or more stem-level phonotactic constraints, e.g. words longer than two syllables, long vowels in non-initial syllables, violations of vowel harmony, etc.<fnref n="23" /> Importantly for our discussion, many of

<footnote n="23">²³Conversely, if the phonotactic constraints of Laal were to hold over the domain of the phonological word rather than the stem, these constraints would be violated by most compounds, i.e. compounds would have to be seen as exceptions.</footnote>
these compounds violate stem-level tonotactic constraints as well in that they display complex tone patterns unattested on uncontroversial one-stem words, in particular ones involving M, as shown in (56) (see also the examples in (36) above). Once analysed as multi-stem words, these fall back into the realm of regular phonotactics, since each one of the stems they are made up of abides by all stem-level phonotactic constraints.

<table><tr><td>(56)</td><td>mùn+gēl</td><td>'Dichrostachys cinerea, tree sp.'</td></tr><tr><td></td><td>mùn+gōw</td><td>'ant sp.'</td></tr><tr><td></td><td>màn+dū</td><td>'dragonfly'</td></tr><tr><td></td><td>màn+gūrmān</td><td>'fish sp. (PL)'</td></tr><tr><td></td><td>màn+mbīlā</td><td>'insect sp.'</td></tr><tr><td></td><td>tuāg+gà+mbīlā</td><td>'bird sp.'</td></tr><tr><td></td><td>mōō+gà+díígí</td><td>'hippopotamus'</td></tr></table>

### 5.3. Morphosyntactic M-lowering: floating [-raised] suffix

The same mechanism accounts for morphosyntactic M-lowering, analysed as the effect of a floating [-raised] suffix flagging the presence of an *in-situ* complement (on a par with the gerund suffix /-V<sup>L</sup>/, or truncating morphology on the irregular nouns mentioned above).<sup>24</sup> This is shown in (57) with the verb /dāg/ ‘drag’ and the noun /nāw/ both followed by a floating [-raised] suffix.

<table><tr><td>(57) /dāg-[raised]/ → [dàg] /nāw-[raised]/ → [nàw]</td><td>‘drag (+OBJECT)’ ‘house (construct form)’</td></tr><tr><td>[-u]</td><td>[-u]</td></tr><tr><td>[+r] / [r]</td><td>→</td><td>[+r] / [r]</td></tr><tr><td>dāg /nāw</td><td>dàg /nàw</td></tr></table>

With H- and L-toned roots, the [-raised] suffix is either stray-erased or fused with the root [-raised], as seen in (58), where L- and H-toned verb roots are represented together.

<table><tr><td>(58) /jàr ~ kár-[raised]/ →</td><td>jàr ~ kár 'sacrifice ~ put (+OBJECT)'</td></tr><tr><td>[-~+u] / [r]</td><td>[-~+u] / [r]</td></tr><tr><td>→</td><td>(or fusion)</td></tr><tr><td>jàr~kár</td><td>jàr~kár</td></tr></table>

<footnote n="24"><sup>24</sup>The analysis of this floating element as a suffix rather than a prefix is justified by the fact that all segmental morphology is suffixal in Laal, which lacks segmental prefixes altogether.</footnote>
## 5.4. Distributional constraint *MX/XM: bidirectional [–raised] assimilation

So far all examples illustrate leftward spreading. This is accidental and due only to the fact that there are no M-toned suffixes that would show rightward spreading of [–raised] from the root (the only M-toned suffix has a replacive tone, as we will see in §6). But the absence of LM and HM patterns in the lexicon (*modulo* the exceptions mentioned at the end of §3) proves that the structure the language seeks to avoid is not only stem-internal [+raised] [–raised], but also [–raised] [+raised], i.e. the constraint is bidirectional: *([a raised] [β raised]$_{STEM}$*. In a constraint-based approach with parallel evaluation, ill-formed inputs with a stem-level LM or HM pattern would violate this constraint. Given the preponderance of M-lowering in the language and the absence of L-raising ([–raised] → [+raised]) or H-lowering ([+upper] → [–upper]), the only possible repair to posit in such cases is progressive [–raised] assimilation/spreading. All potentially ill-formed tone patterns are thus repaired in the same way, as schematised in (59).<fnref n="25" />

<figure><img src="image_8.png" /></figure>

Potential underlying tritonal patterns with one or more M tones would likewise surface with no M tone. This would involve leftward spreading (e.g. *MHL* → *LHL*), rightward spreading (e.g. *LHM* → *LHL*), or both (e.g. *MHM* → *LHL*), as well as indistinct cases (e.g. *HML* → *HL* → *HL*, with [–raised] spreading either from H or from L).

All cases of M-lowering (M instability), as well as the static constraint against complex stem-level patterns involving M (M exclusivity) are thus straightforwardly accounted for by one simple general phonological process ([–raised] assimilation) applying to comply with one simple phonotactic constraint (that against disagreeing [raised] feature sequences within a stem). M-lowering is thus a phonological phenomenon: morpheme concatenation simply creates the phonotactic context triggering [–raised] assimilation. In that sense, the root tone change in this case is no different from the root vowel changes involved in the anticipatory vowel harmony patterns described in (6) and (7) above. I come back to this parallel behavior in the conclusion.

## 5.5. The case of the ventive suffix

The ventive morphology on verbs can be used as another argument in favor of the subtonal approach defended in this paper. The ventive suffix on verbs is segmentally identical to the gerund seen in §4.2.3 above: it consists of a copy of the root vowel. It differs in its tonal behavior. It carries the same tone as the root with H- and L-toned roots. With M-toned roots, on the other hand, the entire ventive form is realised with a L tone – another case of M-lowering. This is shown in (60).

<footnote n="25">²⁵For an Optimality-Theoretic account of M-lowering in Laal, see Lionnet 2022.</footnote>
<table><tr><td>(60)</td><td>H</td><td>kár</td><td>'put'</td><td>kár-á</td><td>'put-VEN'</td></tr><tr><td></td><td>M</td><td>dāg</td><td>'drag'</td><td>dàg-à</td><td>'drag-VEN'</td></tr><tr><td></td><td>L</td><td>jàr</td><td>'sacrifice'</td><td>jàr-à</td><td>'sacrifice-VEN'</td></tr></table>

The fact that this suffix is realised with a L tone in two cases out of three makes it tempting to analyse it as underlyingly L-toned. The H-toned realisation in combination with a H-toned root would then have to be analysed as a case of High tone spread: /kár-V/ → kárá. The problem with this analysis is that this specific High tone spread rule is unique to this suffix: it is not found with any other stratum-2 L-toned suffix following a H-toned root, e.g. /kár-àn/ → káràn 'put-it'. While high tone spread is attested with L-toned inalienable possessive suffixes, as discussed in §6.3, the two processes are not identical. Indeed, in the case of possessive suffixes, the initial H tone of the root spreads only one mora to the right: /tím-àr/ → tímár 'his hand', but /wúúr-àr/ → wúúràr 'his thigh' (cf. examples (71)-(72)). With the ventive suffix, on the other hand, spreading would have to be analysed as unbounded, as evidenced by the trimoraic form /máár-V/ → máárá 'knead-VEN'.

The featural representations proposed above to account for the behavior of the M tone offer a better alternative. I propose to analyse the ventive suffix as consisting of a copy vowel associated with a TRN specified as [-raised], but underspecified for [upper]. Specification of the upper feature comes from the root, which explains the H realisation after H-toned (i.e. [+upper]) roots, and the L realisation after M- and L-toned (i.e. [-upper]) roots, as illustrated in (61), (62), and (63). Additionally, the [-raised] feature of the suffix triggers [-raised] assimilation, thus causing M-toned roots to lower to L, as shown in (63).

(61) /kár-V[-raised]/ → kárá 'put-VEN'

<figure><img src="image_9.png" /></figure>

(62) /jàr-V[-raised]/ → jàrà 'put-VEN'

<figure><img src="image_10.png" /></figure>
(63) /dāg-V[–raised]/ → dàgà ‘drag-VEN’

<figure><img src="image_11.png" /></figure>

The advantage of this representational approach over the high-tone-spread analysis is that it does not posit a morpheme-specific tone rule, and does not treat the ventive suffix as exceptional in its tonal behavior. Rather, this behavior simply results from [–raised] assimilation, which is a general, independently attested tonological rule of the language, and spreading of features to unspecified elements, which is a general mechanism built into the theory of autosegmental phonology (Leben 1973; Goldsmith 1976), which I use here to account for the tonology of Laal.

## 5.6. The emergence of subtonal features and the ambiguity of *M*

I assume that subtonal features, just like segmental distinctive features, are emergent (Boersma 1998; Mielke 2008), i.e. they are ‘created by learners in response to a phonological pattern’ (Mielke 2008: 101). The subtonal specification associated with a tone is not determined *a priori* by the theory. A featural analysis is thus necessarily a bottom-up approach, guided by empirical facts. Consequently, it is not expected that all featural combinations should necessarily be used in a language. Only the ones that are justified by the data are likely to emerge. Subtonal features are not even expected to be necessary in the analysis of all tonal systems. In the absence of any phonological pattern that would benefit from a featural analysis (e.g. tonal patterns showing natural class behavior that cannot be captured by tonal units alone), subtonal features are simply unnecessary to both the learner and the analyst.

The emergent nature of features allows us to address the third argument put forth against subtonal features, that is, the fact that the specification of the Mid tone in a three-tone system is necessarily ambiguous (cf. Hyman 2010; Clements et al. 2010; and references therein). A system with two binary features allows for four combinations, which is perfect for the characterisation of a four-tone system. In a three-tone system, one of these combinations is unattested. In principle, the missing category could be any one of the four possible combinations. There are thus four possible analyses of a three-tone system, as shown in Table 4, and the problem lies in determining which combination is missing.

Yip (2001) rules out options A and D on the basis of the dispersion principle and the pressures it places on inventories: in order for contrastive tones to be maximally distinct phonetically, the two ends of the pitch range must be as far as possible from each other. Consequently, H is always encoded as the highest possible value on the featural scale, i.e. [+upper, +raised], and L as the lowest value, i.e. [–upper, –raised]. The M tone is necessarily one of the two intermediate values – in Yip’s (2001: 162) terms, ‘the gap [is] a missing mid tone, not a missing H or L’.
<table><caption>Table 4: Four possible three-tone systems</caption><thead><tr><th></th><th>A</th><th>B</th><th>C</th><th>D</th></tr></thead><tbody><tr><th>*</th><td>[+u, +r]</td><td>H</td><td>[+u, +r]</td><td>H</td><td>[+u, +r]</td></tr><tr><th>H</th><td>[+u, -r]</td><td>*</td><td>[+u, -r]</td><td>M</td><td>[+u, -r]</td></tr><tr><th>M</th><td>[-u, +r]</td><td>M</td><td>[-u, +r]</td><td>*</td><td>[-u, +r]</td></tr><tr><th>L</th><td>[-u, -r]</td><td>L</td><td>[-u, -r]</td><td>L</td><td>[-u, +r]</td></tr><tr><th></th><td></td><td></td><td></td><td>*</td><td>[-u, -r]</td></tr></tbody></table>

I contend that dispersion is active in phonetic implementation (i.e. in translating the featural specifications into actual sounds), but not in determining feature specifications in the first place. In general, there need not be a one-to-one correspondence between specific featural specifications and specific pitch ranges. A system with three different subtonal feature combinations is expected to be interpreted as a partition of the total pitch range into three equidistant pitch targets, irrespective of the exact featural specifications of the three combinations. In other words, the highest tone does not have to be [+upper, +raised] in order to be interpreted as a pitch target located toward the higher end of the pitch range, maximally different from the pitch target corresponding to the lowest tone in the system.<fnref n="26" />

In an emergent approach, all four options in (4) are in principle possible, as long as they are evidenced by phonological patterns. The only (trivial) restriction needed is a form of paradigmatic phonetic naturalness: the relative position of the different featural combinations on the featural scale should correspond to the relative position of the corresponding pitch targets within the pitch range (i.e. H corresponds to the highest feature combination irrespective of its actual featural content, L to the lowest one, M to a combination intermediate between that of H and that of L). The choice of the missing combination is entirely determined by the phonological pattern under analysis.

Whether all four types in (4) are indeed attested or not cannot be confirmed at this point, given the very limited number of three-tone systems that have been given a featural analysis so far. Laal is a system of type A, as clearly shown by the behavior of the Mid tone: *MX/XM and M-lowering both characterise M as [–upper, +raised] ([+raised] because it is targeted by [–raised] assimilation, [–upper] because it merges with L under assimilation) and H as [+upper, –raised] ([–raised] because it triggers [–raised] assimilation, just like L, and [+upper] because it is higher than both M and L and in contrast with L which is also [–raised]). The feature combination [+upper, +raised] has no use in the system, and is thus naturally absent from the tonal inventory.

<footnote n="26">²⁶A possible alternative to Yip's (2001) proposal would be to rule out B and C by restricting the theory to allow only for adjacent (non-gapped) combinations, as a phonological representation of the equidistance between pitch targets. In this case, the missing combination would always be a high or a low tone, never a mid tone. The indeterminacy is about whether the mid tone is part of the upper or lower register.</footnote>
Snider (2020: 101) analyses Acatlán Mixtec as a language of type B,<fnref n="27" /> while Gjersøe et al. (2019) propose to view Limbum as instantiating type C.<fnref n="28" /> I don’t know of any language or analysis corresponding to type D, where the missing combination is the lowest on the featural scale, but in the emergent approach to subtonal features taken here, there is no reason to exclude it a priori.

To conclude, the subtonal specification of the mid tone in a three-tone system is not necessarily ambiguous. In the three languages mentioned above, the featural content of the mid tone can clearly be established by the analyst on the basis of its behavior with respect to the other tones. Systems in which the subtonal specification of the mid tone cannot be established might simply be cases where evidence for subtonal features is lacking, i.e. systems whose learning is unlikely to lead to the creation of something like a feature system in the learner’s grammar, and whose analysis does not require it.

**6. Evidence for the tonal root node: full tone spread and deletion**

Tonal interaction in Laal is not limited to subtonal processes: some tonal alternations do involve interaction between full tones. Tones are thus not just the emerging result of combinations of subtonal features, but may also act as units, i.e. be referred to as units by the phonological grammar. This is made possible by the Tonal Root Node (TRN) in the tone geometry in (52) above. Three such processes are attested in the morphotonology of Laal: base pattern reduction under suffixation (§6.1), replacive grammatical tone (§6.2), and High tone spread in inalienable possessive morphology (§6.3).

**6.1. Base pattern reduction under suffixation**

Stratum-2 suffixes require their base of affixation to bear only one tone, which has been the case in all the examples presented until now. If the base of suffixation bears a complex tone pattern, this pattern is simplified by deletion of all but its first tone: /T₁T₂-sfx/ → /T₁-sfx/ (only the bitonal patterns LH and HL are ever attested in the relevant contexts). This reduction is observed irrespective of the nature of the base (noun or verb) or affix (inflectional, derivational), and irrespective of the base and suffix tones. This is shown in the examples below, where the LH (64) and HL (65) root patterns are systematically changed to L and H respectively upon suffixation, whether

<footnote n="27">²⁷Snider’s analysis is complex and resorts to underspecification and default feature specifications. The register feature *l* (≈ [–upper]) is analysed as default, and the tonal features H and L ([+raised] and [–raised] respectively) are considered to correlate by default with the higher and lower register features respectively. The low tone is analysed as underlyingly Ø; it receives default *l*, then the register feature L, by default associated with *l*. Its surface specification is thus L/l (≈ [–upper, +raised]). The mid tone is underlying specified as H (≈ [+raised]), but underspecified for register; it thus receives default *l* and is on the surface specified as H/l (≈ [–upper, +raised]). This specification of the mid tone is necessary to account for a pervasive alternation between mid and low in disyllabic mid-toned words: both must share the same register feature *l*. Finally, the high tone is underlyingly specified for the register feature *h*, but underspecified for tone; it thus receives the H tone feature that correlates by default with *h*, and ends up being specified as H/h (≈ [+upper, +raised]). The combination L/h (≈ [+upper, –raised]) is unattested.</footnote>

<footnote n="28">²⁸Using Snider’s (1999; 2020)’s register and tone features, the authors show that the M tone has to be specified as L/h (≈ [+upper, –raised]) because it forms a natural class with H (defined by the register feature *h*≈[+upper]). They consider that the other “mid” combination, i.e. H/l (≈ [–upper, +raised]), is unnecessary in the analysis of the tonal system of the language and thus “not part of the tonal lexicon.”</footnote>
the suffix is L, as in (64a) and (65a), H, as in (64b) and (65b), or LH, as in as in (64c) and (65c).<fnref n="29" />

(64) LH bases

a. *With L suffixes*

<table><tr><td>/duàgál-àr/ → duàglàl</td><td>'his upper arm'</td></tr><tr><td>/gààw-àr/ → gààwàr</td><td>'his armpit'</td></tr><tr><td>/sèègé-àn/ → siààgàn</td><td>'shake it'</td></tr><tr><td>/sǒn-àn/ → sàŋàn</td><td>'fight it'</td></tr></table>

b. *With H suffixes*

<table><tr><td>/duàgál-rú/ → dòglú</td><td>'our (EX) upper arm'</td></tr><tr><td>/sèègé-án/ → siààgán</td><td>'shake him'</td></tr><tr><td>/sǒn-án/ → sàŋán</td><td>'fight him'</td></tr></table>

c. *With a LH suffix*

<table><tr><td>/sèègé-nǐ/ → sèègnǐ</td><td>'shake them (M/F)'</td></tr><tr><td>/sǒn-nǐ/ → sòŋnǐ</td><td>'fight them (M/F)'</td></tr></table>

(65) HL bases

a. *With a L suffix*

<table><tr><td>/págár-àn/ → págràn</td><td>'think about it'</td></tr><tr><td>/táàb-àn/ → táábàn</td><td>'cause distress to it'</td></tr></table>

b. *With a H suffix*

<table><tr><td>/págár-án/ → págrán</td><td>'think about him'</td></tr><tr><td>/táàb-án/ → táábán/</td><td>'cause distress to him'</td></tr></table>

c. *With a LH suffix*

<table><tr><td>/págár-nǐ/ → págórňi ~ págrňi</td><td>'think about them (M/F)'</td></tr><tr><td>/táàb-nǐ/ → táóbnňi</td><td>'cause distress to them (M/F)'</td></tr></table>

Forms like /duàgál-àr/ → duàglàl or /sèègé-àn/ → siààgàn in (64a) may suggest that the tone reduction on the base is due to V2 deletion, applying to avoid creating a trisyllabic stem. However, the forms /gààw-àr/ → gààw-àr or /sǒn-àn/ → sàŋ-àn clearly show that tone pattern reduction is independent of V2 deletion, and is only caused by the presence of the suffix. Furthermore, the existence of stem-level LHL and HLH patterns shows that reduction is not caused by the necessity to avoid tritonal stem patterns.

<footnote n="29">²⁹The only complex pattern attested in the 65 nouns compatible with inalienable possessive suffixes is LH, and the only tones attested on possessive suffixes are L and H.</footnote>

<footnote n="30">³⁰In the case of *dòglù*, the initial /r/ of the suffix is deleted to avoid creating a triconsonantal cluster.</footnote>

<footnote n="31">³¹CV(V).CVC verbs combining with C-initial suffixes pose a number of phonotactic problems: V2 deletion is expected to apply in order to avoid creating a trisyllabic form, but it creates a new phonotactic problem by yielding a triconsonantal cluster, impossible in the language. One solution to the latter problem is the deletion of one of the consonants: either the last consonant of the root, or the first consonant of the suffix, which is not seen anywhere else in the language and seems to be a last-resort solution, with much intra- and inter-speaker variation. The two variants presented here are the trisyllabic variant *págárňi*, where the non-application of V2 deletion avoids the triconsonantal cluster /grn/, and the version with V2 and consonant deletion: *págri*.</footnote>
The examples above all involve pronominal suffixes. The following examples further show that pattern reduction occurs with the ventive, associative, and medio-passive suffixes, i.e. all stratum-2 suffixes except the gerund /-V<sup>L</sup>/ and passive /-Vl<sup>M</sup>/ suffixes, whose tones are replacive, as discussed in §6.2.

(66) a. /yùgár-V<sub>[-r]</sub>/ yùgrà ‘shake-ven’

b. /yùgár-V̄/ yùgrá ‘shake-ass’

c. /yùgár-íŋ/ yùgríŋ ‘shake-mp’

We saw that the ventive suffix is tonally deficient: it is specified as [–raised] and gets its [upper] feature value from the last tone of the base of affixation. When following a LH root, as in (66a) /yùgár-V<sub>[-r]</sub>/, the [upper] specification inherited by the suffix is not the [+upper] of the final H tone of the root (*yùgr-à), but the [–upper] of the initial L tone (yùgr-à), after deletion of the H tone, i.e. after base reduction. This indicates that the spreading of the root [upper] feature to the underspecified vowel of the suffix occurs after V2 deletion – very likely postlexically, as do most default structure-filling rules.

Base pattern reduction can be represented as the deletion of all but the initial TRNs of the base of affixation (in effect, deletion of the second of two TRNs, since no tritonal pattern is attested in the relevant contexts). This is illustrated in (67).

(67) /sðp-àn/ → sàpàn ‘fight it’

<figure><img src="image_12.png" /></figure>

## 6.2. Full-tone spread in replacive tone patterns

Two suffixes display “replacive” tone (Welmers 1973: 132–133), i.e. they impose a single tone pattern to their stem, wiping out the underlying tone of the root to which they attach. These two suffixes are gerund /-V<sup>L</sup>/ seen in §4.2.3 and Table 3, and passive /-Vl<sup>M</sup>/). Both are illustrated in (68) with H-, M-, and L-toned verbs. In both cases, the vowel of the suffix is realised as a copy of the root vowel.

(68) a. *H verb stems* Gerund /-V<sup>L</sup>/ Passive /-Vl<sup>M</sup>/

<table><tr><td>kár</td><td>‘put’</td><td>kàr-à</td><td>kār-āl</td></tr><tr><td>siáág</td><td>‘close’</td><td>siààg-à</td><td>siāāg-āl</td></tr><tr><td>síráŋ</td><td>‘take out’</td><td>sìrŋ-à</td><td>sīrŋ-āl</td></tr></table>

b. *M verb stems* Gerund /-V<sup>L</sup>/ Passive /-Vl<sup>M</sup>/

<table><tr><td>dāg</td><td>‘drag’</td><td>dàg-à</td><td>dāg-āl</td></tr><tr><td>juāŋ</td><td>‘buy’</td><td>juàŋ-à</td><td>juāŋ-āl</td></tr><tr><td>tūrūg</td><td>‘sew’</td><td>tùrg-ù</td><td>tūrg-ūl</td></tr></table>
<table><thead><tr><th>c. L verb stems</th><th>Gerund /-V<sup>L</sup>/</th><th>Passive /-Vl<sup>M</sup>/</th></tr></thead><tbody><tr><td>jär 'sacrifice'</td><td>jär-à</td><td>jār-āl</td></tr><tr><td>lòb 'wet'</td><td>lòb-ò</td><td>lōb-ōl</td></tr><tr><td>lùrùg 'shorten'</td><td>lùrg-ù</td><td>lūrg-ūl</td></tr></tbody></table>

These two suffixes contrast with all other segmental suffixes, whose tones are never replacive, e.g. /kár-àn/ → [káràn] (*[káràn]) ‘put-it’, /jàr-án/ → [jàrán] (*[járán]) ‘sacrifice-him’. This replacive pattern corresponds to what Rolle (2018: 47) calls “replacive-dominant grammatical tone”, defined as a tone pattern associated with a specific morpheme or morphological construction which deletes and replaces the underlying tone of its target. It is beyond the scope of this paper to offer an analysis of dominance and replacive grammatical tone. The reader is referred to Rolle (2018); Sande et al. (2020); Trommer (in press) for recent proposals (and references therein for previous accounts). For now, I simply represent the dominance of the tone pattern imposed by the gerund and passive suffixes with a diacritic mark on the TRN (‘d’ for ‘dominant’). The main point here is that these patterns involve spreading and deletion of entire TRNs, justifying the tone geometry in (52), as illustrated in (69) and (70).

(69) /kár-V<sup>L</sup>/ → kàrà ‘put-GER (+OBJECT)’

<figure><img src="image_13.png" /></figure>

(70) /kár-Vl<sup>M</sup>/ → kārāl ‘put-PAS’

<figure><img src="image_14.png" /></figure>

Neither the replacive L of the gerund nor the replacive M of the passive can be analysed as involving subtonal interaction alone. The universal change to L observed with the gerund requires both [–raised] (M→L) and [–upper] (H→L) assimilation/spreading, i.e. full assimilation, better represented as TRN spreading. As for the passive suffix, the systematic change to M that it triggers could be viewed as a case of regressive [+raised] assimilation/spreading.<fnref n="32" /> This would straightforwardly account for the L-to-M change observed with L-toned roots. With H-toned roots, one additional step would be required: spreading the suffixal [+raised] to the root would create a [+upper, +raised] combination, unattested in the language. The [+upper]

<footnote n="32">³²The suffix could even be said to carry only a [+raised] feature, the [–upper] feature being redundant in this case.</footnote>
feature of the root would then have to be changed to [-upper] to comply with the con-
straints of the inventory. This abstract extra-step is unnecessary in the TRN-spreading
analysis in (70) above. Furthermore, this would be the only case of [+raised] assimila-
tion/spreading, all the more suspicious that it goes against the otherwise exceptionless
[-raised] assimilation/spreading at work in the language.

The fact that there are no non-replacive M-toned suffixes is intriguing. One could hypothesise that the replaciveness of suffixal M is a last-resort solution to preserve the grammatical information conveyed by the suffix. Indeed, in order to comply with the unviolable *MX/XM constraint, there are two solutions: either change the suffixal M (e.g. to L, as in other cases of M-lowering), or change the lexical tone of the root to M, in order to keep the suffix intact – which appears to be what Laal does. The problem is that such an explanation is not available for the replacive L tone of the gerund, which has no need to be replacive. Like the other L-toned suffixes (e.g. third person neuter object /-än/ seen in (10), (11) and (53)–(55)), it could indeed in theory be kept without violating any tonotactic constraint (other than *MX/XM when attaching to a M-toned root, in which case M-lowering of the root M would apply, as it does elsewhere). In other words, the last-resort analysis does not generalise to all cases of replacive tone. Replaciveness thus has to be accounted for in its own terms.

6.3. *High Tone Spread in inalienable possessive morphophonology*

When a H-toned noun root combines with a L-toned inalienable possessive suffix, the H tone of the root spreads one (and only one) mora to the right. If the first syllable of the resulting stem is monomoraic, the H spreads onto the suffix, deleting its L tone, as in (71) (all examples in this section take the third person singular suffix -àr for illustration).<fnref n="33" />

<table>
  <tr>
    <td>(71)</td>
    <td>/tím-àr/</td>
    <td>tímár</td>
    <td>(*tímàr)</td>
    <td>'his hand'</td>
  </tr>
  <tr>
    <td></td>
    <td>/kúrá-àr/</td>
    <td>kúrár</td>
    <td>(*kúràr)</td>
    <td>'his leg'<sup>34</sup></td>
  </tr>
  <tr>
    <td></td>
    <td>/ság-àr/</td>
    <td>ságár</td>
    <td>(*ságàr)</td>
    <td>'his brother-in-law'</td>
  </tr>
</table>

If the first syllable is bimoraic, on the other hand, the H does not spread onto the suffix, which keeps its low tone, as in (72).

<table>
  <tr>
    <td>(72)</td>
    <td>/wúúr-àr/ wúúràr</td>
    <td>(*wúúrár)</td>
    <td>'his thigh'</td>
  </tr>
  <tr>
    <td></td>
    <td>/ndáár-àr/ ndáárár</td>
    <td>(*ndáárár)</td>
    <td>'his skull'</td>
  </tr>
  <tr>
    <td></td>
    <td>/piáár-àr/ piáárár</td>
    <td>(*piáárár)</td>
    <td>'his lower leg'</td>
  </tr>
</table>

This H tone spread can easily be analysed as the spreading of the initial H tone’s
TRN one mora to the right, as shown in (73) and (74).

<footnote n="33"><sup>33</sup>Inalienable possessive suffixes are either L-toned (/-àr/ ‘my’, -à/ ‘your’, -àr/ ‘his/, -ò(g)/ ‘her’, -àn/ ‘its’ and /-uàn/ ‘their (n)’) or H-toned (/-rù/ ‘our (ex)’, -rán/ ‘our (in)’, -rùn/ ‘your (pl)’ and /-ri/ ‘their (M/F)’).</footnote>

<footnote n="34"><sup>34</sup>This form involves V2 deletionn: /kúrá-àr/ → kúr-àr → kúrár.</footnote>
<figure><img src="image_15.png" /></figure>

<figure><img src="image_16.png" /></figure>

High Tone Spread is regular within the closed class of nouns compatible with inalienable possessive suffixes,<fnref n="35" /> and provides additional evidence for the TRN. Indeed, a subtonal feature analysis offers no advantage. One featural analysis that would capture the data consists in analysing this pattern as involving rightward [+upper] spread from the initial mora onto the following mora. Indeed, replacing the [–upper] feature of the L-toned suffix with a [+upper] specification changes it to a H tone, since both H and L are [–raised]. Both analyses are descriptively adequate, and it is impossible to find definitive evidence in favor or against either one. The fact that the [upper] feature is not involved in any active spreading/assimilative pattern elsewhere in the language (the spreading involved in the realisation of the ventive suffix is only structure-filling), and that cases of TRN spread are independently attested militate in favor of the TRN-spread analysis of High Tone Spread.

## 7. Alternatives

In this section, I argue that the subtonal approach proposed above is stronger than two more classical alternatives: a tone-as-unit analysis (§7.1) and an analysis of M as /0/ (§7.2). Finally, I sketch a tentative analysis in terms of one gradient tone height feature (§7.3), which appears to be a promising competitor to the subtonal feature analysis, but currently lacks empirical support. Finally, a variant of the subtonal analysis proposed above where the M tone is only partially specified is developed in (§7.4).

### 7.1. Tone-as-unit analysis

A featural analysis would be unwarranted if it could be demonstrated that an analysis resorting only to the tonal primitives H, M, and L accounts for all the facts listed in (50) above. I show in this section that such an analysis is impossible without stipulating (i.e. circularly including the descriptive generalisation in the analysis) some of the points in (50).

<footnote n="35">³⁵There are only three exceptions, ignored here.</footnote>
Instead of positing subtonal features and viewing M-lowering as resulting from [–raised] assimilation, one could analyse M-lowering as involving a L assimilation rule targeting M tones within the stem. This can be represented as spreading of L onto M followed by delinking of the M tone, as shown in (75) and (76) below. This would straightforwardly account for morphophonological M-lowering before a L-toned suffix (75), as well as morphosyntactic M-lowering, analysed as involving a floating L (rather than [–raised]) suffix (76).

(75) $\begin{array}{ccc} \bar{n} \bar{a} g & - \bar{a} n & \rightarrow \\ | & | & \\ M & L & \end{array}$ $\begin{array}{ccc} \bar{n} \`a \`g & - \`a \`n & \rightarrow \\ | & | & \\ M & L & \end{array}$ 'eat it'

(76) $\begin{array}{ccc} \bar{n} \bar{a} g & | & \rightarrow \\ | & | & \\ M & \text{(.L)} & \end{array}$ $\begin{array}{ccc} \bar{n} \`a \`g & | & \rightarrow \\ | & | & \\ M & \text{(.L)} & \end{array}$ 'eat +OBJ'

There are at least three problems with this approach. First, it does not account for morphophonological M-lowering before a H-toned suffix – unless one posits a floating L before every H-toned suffix in the language, as in (77), for which there is no independent evidence.

(77) $\begin{array}{ccc} \bar{n} \bar{a} g & - \bar{a} n & \rightarrow \\ | & | & \\ M & \text{(.L)} & H \end{array}$ $\begin{array}{ccc} \bar{n} \`a \`g & - \`a n & \rightarrow \\ | & | & \\ M & \text{(.L)} & H \end{array}$ 'eat him'

Note that this floating L tone cannot be viewed as marking the presence *in situ* of the object of the verb, nominal or pronominal, as in example (75) and (77). Indeed, we saw that M-lowering does not apply solely before object suffixes, but before all stratum-2 suffixes, including suffixes unrelated to the presence of the object or even transitivity at large, e.g. medio-passive /-íp/ and instrumental /-V/, which we saw is compatible with intransitive verbs.

An alternative to explain why M changes to L before H would be to posit a M to L change satisfying the *MX/XM phonotactic constraint. This solution is far from satisfactory, as it consists solely in formalising the surface descriptive generalisation, i.e. stipulating the alternation rather than accounting for it. The featural analysis I propose does not stipulate M-lowering, but derives it from the properties of the subtonal features that make up the three tones H, M, and L, i.e. from simple representations not directly related to the surface pattern it purports to analyse. These representations, in turn, are not stipulated, but posited on the basis of evidence consisting of natural classes involved in an assimilation process and defined by common phonological behavior (H and L are both triggers, M is the only target, M and L merge under assimilation).

The second problem with the tone-as-unit analysis is that L spreads only onto a preceding M and never a preceding H, which does not follow from any property of the three tones H, M and L, and must be stipulated. In the subtonal approach, on the other hand, the featural makeup of each tone directly explains their different behaviors: H is immune to lowering because lowering is [–raised] assimilation, and H is already specified as [–raised]; M being [+raised], it is by necessity the only possible target of [–raised] assimilation.
Finally, the *MX/XM phonotactic constraint on stem-level tone patterns is not fully accounted for in the tone-as-unit analysis. While the absence of *ML and *LM patterns can be explained through bidirectional L spreading, the absence of *MH and *HM has to be stipulated – or explained by positing a floating L tone between H and M, which, again, is not independently motivated.

Note, also, that with the tone-as-unit approach, the ventive suffix would have to be analysed as carrying a full tone, e.g. a L tone subject to high tone spread, as suggested in §5.5 above. This is not impossible of course, in particular given that high tone spread is attested in possessive morphology. But, as discussed in §5.5, it is a morpheme specific tonal process that is unnecessary in the featural approach.

## 7.2. Mid as zero

The exclusivity and instability of the M tone in Laal suggests a certain weakness of the M tone compared to both H and L. This weakness is not analysed as such in the featural approach I propose, where M is weak only by virtue of being specified as [+raised], which makes it a target of [-raised] assimilation. An alternative analysis could be proposed which represents M weakness more directly, for example by analysing M as Ø within a tone-as-unit analysis. The weakness of the M tone could indeed be seen as evidence of its underlying non-existence and default status. That is, the only two underlying tones of Laal are H and L, with TBUs specified as H, L, or Ø. Ø TBUs get their tonal specification through spreading of neighboring tones, otherwise through default M insertion. This would naturally explain the static *MX/XM constraint, as well as M-lowering before a L tone, as seen in (78) and (79).<fnref n="36" />

(78) j̥ag -àn → p̥àg -àn ‘eat it’
| L |   | L |

(79) j̥ag → p̥àg ‘eat +OBJ’
| (L) |   | (L) |

However, it would pose the same problem as the preceding analysis, i.e. it would still fail to account for M-lowering before a H-toned suffix without gratuitously positing a floating L tone before all such suffixes (or giving up on accounting for it and stipulating a M to L tone change instead, to avoid a violation of *MX/XM), as shown in (80).

(80) j̥ag -án → p̥àg -án ‘eat him’
| (L) H |   | (L) H |

In general, any tone-as-unit approach runs into one fatal problem, which is that it cannot account for the fact that both H and L trigger M-lowering without stipulating all

<footnote n="36">³⁶In this analysis, the passive suffix would have to be analysed as consisting solely of subtractive morphology. The suffix deletes the tone(s) of the verb root (as it does in the featural analysis, and as it would have to do in any analysis), but since it is itself toneless, the resulting form is assigned default M tone: /kár-subVl/ → kar-al → kārāl.</footnote>
or part of the description in the analysis. That is, a tone-as-unit analysis fails to capture the natural class formed by the two non-adjacent tones H and L – which the subtonal feature approach straightforwardly accounts for, as we saw.

### 7.3. Tone height as one gradient feature

One final alternative I will consider is to view tone height, not as a combination of two features, but as one gradient feature.<fnref n="37" /> I do not have space here to go into details. I only give a brief sketch, and leave the full development and evaluation of this alternative to future research.

Let us represent tone height as one single gradient feature [*n* T-height], with *n* arbitrarily comprised between 0 (the lowest tone height) and 1 (the highest). This is the gradient equivalent of a multivalued feature (cf. Trubetzkoy 1939; Ladefoged 1971; Lindau 1978; Clements 1991, 2015). On the scale from [0 T-height] = L to [1 T-height] = H, M would occupy an intermediate position. If this position were to be defined as closer to L than to H, say [0.4 T-height], this would explain both the \*MX/XM constraint and M-lowering, as I show below.

With such representations, the \*MX/XM constraint can be restated as \*ΔT-height<1, i.e., within a stem, adjacent tones must be distant by at least 1 T-height level. Consequently, only HL [1-0] and LH [0-1] sequences are allowed. Any sequence involving a M tone violates this constraint since the distance is always less than 1: ΔT-height(H~M) = .6, and ΔT-height(L~M) = .4. The optimal repair to this violation is to change the M tone to L, because L is the closest tone in terms of T-height distance (.4, whereas the distance between M and H is .6). Changing M to L thus incurs a lesser violation of faithfulness (on the condition that violation of IDENT-T-height is defined as gradient). In this alternative, M-lowering is analysed as a M to L tone change, but the tone change does not need to be stipulated: it is motivated by the proximity of M with L on the tone-height gradient.

The main challenge with such an alternative analysis is to justify the asymmetric position of M on the T-height scale. As it currently is, the theory has to stipulate it. Instrumental data are necessary to determine whether M is indeed on average realised closer to L than to H. I have not conducted this acoustic analysis. This alternative must thus remain at a tentative stage for now. It seems worth sketching it here, however, as it appears to be a potential competitor to the subtonal analysis proposed in this paper.

### 7.4. Alternative subtonal analysis

One anonymous reviewer suggests another account of the weakness of M, couched in the featural analysis I propose in this paper. In this analysis, M is specified as [–upper] and unspecified for [raised]. This would work for all cases of M-lowering, analysed as spreading of the [–raised] feature of the suffix onto the [raised]-deficient TRN of the root M. All suffixes (except the passive) are indeed specified as [–raised]: H, L(H) and the floating [–raised] of the transitive and genitive suffixes. This is illustrated in (82)

<footnote n="37">³⁷Thanks to Stephanie Shih for suggesting gradience as an alternative.</footnote>
and (81) below with H- and L-toned verbal suffixes and the floating [–raised] suffix respectively.

(81) /dag-àn~-án/ → dàgàn ~ dàgán ‘drag it~him’

<figure><img src="image_17.png" /></figure>

(82) /dag-[–raised]/ → dàg ‘drag (+OBJECT)’

<figure><img src="image_18.png" /></figure>

One would have to posit [+raised] as the default value of [raised], assigned to
[raise]-deficient TRNs in the absence of any available (i.e. spreadable) [–raised] in the
stem, as illustrated in (83). Since [+raised] is never active in the tonology of Laal, this
does not seem to be problematic.

(83) /dag/ → dāg ‘drag’

<figure><img src="image_19.png" /></figure>

The passive suffix would have to be analysed as a replacive defective TRN: a TRN
specified only as [–upper] which spreads and deletes the TRNs of the root, and then
sees its missing [raised] feature filled in by default [+raised] insertion, as in (84).

(84) /kár-VlM/ → kārāl ‘put-PAS’

<figure><img src="image_20.png" /></figure>

This analysis is as descriptively and explanatorily adequate as the full-specification
analysis I propose in §5 above. However, I think it is slightly less satisfactory, for two
<table><caption>Table 5: TRN and subtonal features in Laal regular tonal morphophonology</caption><thead><tr><th>Tonal phenomenon</th><th>TRN (full tone)</th><th>Subtonal features</th></tr></thead><tbody><tr><td>1. M tone behavior:<br/>– Static *MX/XM<br/>– M-lowering</td><td>—</td><td>[–raised] assimilation</td></tr><tr><td>2. Ventive suffix<br/>specification</td><td>—</td><td>[–raised] specification,<br/>unspecified [upper]</td></tr><tr><td>3. Base pattern reduction</td><td>TRN deletion</td><td>—</td></tr><tr><td>4. Replacive tone</td><td>TRN spread and deletion</td><td>—</td></tr><tr><td>5. High Tone Spread</td><td>TRN spread (and deletion)</td><td>—</td></tr></tbody></table>

reasons. First, it requires default [+]raised insertion, and the definition of a default value of [raised], which is unnecessary in the full-specification analysis.<fnref n="38" />

Secondly, it offers an unnecessarily complex representation of the contrast between L and M, which is robust in the language, despite the frequency of M-lowering. Indeed, in this approach, L and M contrast underlyingly by the specification vs. non-specification of the feature [raised]. That is, they differ not only by the fact that, on the surface, one is [–raised] and the other [+raised], but also by the timing of the assignment of the [raised] feature value. This is of course an option that is made entirely possible by the theory and is not in and of itself problematic. But I don't see any necessity to resort to this level of abstraction or complexity. In any case, this analysis can be considered a variation of the one I propose, and does not question the aptness of subtonal features for the analysis of the tonology of Laal.

## 8. Conclusion

In conclusion, the subtonal analysis proposed in this paper provides a simple, unified analysis of the tone system of Laal, which involves both processes manipulating subtonal features and ones manipulating full tonal root nodes, as summarised in Table 5. This analysis is motivated by the behavior of the M tone, which constitutes evidence against the four main counter-arguments to subtonal features listed in (3), and answers all the questions listed in (50). Laal provides evidence for the existence of assimilation patterns involving subtonal features: [–raised] assimilation in this case, which offers a unified analysis of both the *MX/XM constraint and all cases of M-lowering. This, in turn, provides evidence for subtonal natural classes. First, [+raised] defines the M tone as the natural class of targets of M-lowering, which explains why only M fails to take part in complex stem-level tone patterns (question (50a)) and why only M is affected by lowering (question (50b)). Secondly, [–raised] defines the natural class of triggers: H and L; this explains why M is changed to L when followed by both L and H (question (50c)). This is particularly important in that it provides evidence that non-adjacent tones can interact, a prediction made by the two-feature model

<footnote n="38">³⁸The ventive suffix is analysed as unspecified for [upper], but this is morpheme-specific, does not require the definition of a default value of [upper], and in general does not pertain to the general phonology of the language.</footnote>
which was thought until now to lack empirical support (see in particular Clements et al. (2010)). Finally, the feature [–upper] defines the natural class consisting of M and L, which accounts for the fact that M is changed to L rather than H (question (50d)). One can interpret the M→L lowering process as a form of register simplification: for the creation of complex tone patterns and for marked forms of genitive head nouns and transitive verbs, the two registers [+upper] and [–upper] are each reduced to their [–raised] tone.

Finally, the specification of M in Laal is not ambiguous. M→L lowering unambiguously shows that M must be specified as [+raised], hence also as [–upper]. Additionally, the insensitivity of H to [–raised] assimilation demonstrates that the only possible specification for H is [+ upper, –raised]. There is no *a priori* incompatibility between tone features and three-tone systems.

Analysing tone as a feature bundle puts it on a par with segments. This similarity between tonal and segmental phonology is particularly noticeable in Laal, where [–raised] assimilation in response to the *[α raised][β raised] STEM constraint is very reminiscent of vowel harmony. It could, indeed, be described as a case of [–raised]–dominant tone harmony, similar to the many documented cases of ATR harmony with dominant [+ATR] or [–ATR] (Casali 2003, 2008, 2016; Rose 2018, among others). Additionally, just like segments, a tone (i) has the capacity to be either partially active (through one of its features) or fully active (through its root node), and (ii) may be fully or only partially specified in underlying representation, as with the ventive suffix seen in §5.5.

Laal thus joins the growing cohort of languages (e.g. Seenku, McPherson 2016; Babanki, Akumbu 2019; Limbum, Gjersøe et al. 2019; Tenyidie, Meyase 2021; Gaahmg, Trommer 2021) that have recently been shown to demonstrate the aptness of subtonal features in phonological analysis. Laal is especially interesting in showing that the validity of subtonal features is not limited to four-height tone systems.

**Competing interests.** The author declares no competing interests.

**Acknowledgements.** I am indebted to the Laal speakers who patiently taught me their language and sat with me as I was asking them the strangest questions, in particular Kalem Dakour, Adoum Kalem, and Kabo Najara. I also wish to thank Ben Eischens, Chris Geissler, Larry Hyman, Sharon Inkelas, Nicholas Rolle, Hannah Sande, Stephanie Shih, and Thom van Hugte for useful discussion and feedback, as well as audiences at the Humboldt University Linguistics Colloquium, CLS 49, and AMP 2021. An earlier description of the M-lowering data presented in §§ 3 and 4 can be found in Lionnet (2015), and a preliminary version of the featural analysis is proposed in Lionnet (2022).

**Funding statement.** This research was partly funded by the Volkswagen Foundation DoBeS (Documenta-
tion of Endangered Languages) program (grants #85538 and #89843).

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