1. Introduction

There is increasing evidence that language sounds which appear to be ‘the same sound’ are in some cases actually distinct from each other, with consequences for phonological analysis. The classification of sound categories is of great importance to understanding the phonological organization in a language, and close attention to small phonetic differences has contributed to the development of both Lexical Phonology (Mohanan, 1982; Kiparsky, 1982) and Articulatory Phonology (Browman & Goldstein, 1986, 1992).

The effect of sameness may arise from categorical perception (Liberman et al., 1957; Harnad, 2003); the fact remains that native speakers do not necessarily attend to all distinctions in speech sounds. For example, sometimes segments with different phonetic properties are classed together as a single sound, such as the different articulations of American English /ɹ/ (Delattre & Freeman, 1968; Mielke et al., 2010; Archangeli et al., 2011; Mielke et al., 2016) and the different acoustics of American English /s/ (Baker et al., 2011). Another class of relevant examples is neutralization, both incomplete and complete. Most striking are instances of incomplete neutralization, where two sounds from different sources were considered to be the same but were later revealed to be slightly different under close phonetic examination (see Port, 1996 and Yu, 2007 for summaries of the issues; final devoicing examples are found in Port & O’Dell, 1985, Warner et al., 2004; Winter & Röttger, 2011 among others; English [l] in Lee-Kim et al., 2013; tonal near neutralization in Myers & Tsay, 2008; Cheng et al., 2013; incomplete nasal place assimilation in Stephenson & Harrington, 2002; coronal-velar nasal-obstruent heteromorphemic sequences in English in Barry, 1991, and Korean heteromorphemic palatalization in Sung, 2015). Incomplete neutralizations contrast with complete neutralization, for example complete neutralization of manner for coronals in Korean codas (Kim & Jongman, 1996) and of pre-velar nasals in Italian (Celata et al., 2013). Sometimes in the same language both complete and incomplete neutralization are found, depending on the context: Nasal-obstruent place assimilation in Spanish is complete with a following stop, but it is partial with a following fricative (Kochetov & Colantoni, 2011); /s/+/j/ in English varies depending on intervening boundary type (Zsiga, 1995).

Such examples raise a question about ‘exceptions’ to otherwise general phonological patterns when a sound appears to have anomalous behavior: Is this truly an exception, inconsistent with the general pattern, or does closer phonetic examination suggest that in fact the sound was misperceived and there is a systematic pattern? To illustrate, the earliest description of Okpẹ vowels (Hoffmann, 1973) is used as an example of absolute neutralization (Kenstowicz & Kisseberth, 1979): It appears that /ɪ/ and /e/ neutralize to [e], /ʊ/ and /o/ neutralize to [o]. However, Omamor (1973) includes a pilot study suggesting that the high retracted and mid advanced vowel pairs have slightly different formant values—in which case this is not absolute neutralization. Similarly, Mutaka (1995) assumes that Kinande short low vowels are exempt from an otherwise general tongue root advancement harmony, being retracted even in advanced environments; ultrasound examination (Gick et al., 2006) reveals that low vowels have advanced tongue root in advanced contexts. In short, all vowels participate in tongue root harmony and the Kinande pattern is completely symmetric.

Another potential example comes in the phenomenon called nasal substitution, occurring in Austronesian languages, including the Malayo-Polynesian languages Sasak and Javanese. Nasal substitution refers to morphological pairing of obstruent-initial and homorganic nasal-initial forms—except that [s] pairs with a sound described as [ɲ] in both Sasak and Javanese. Our question is whether closer inspection reveals that [s] and the nasal morphologically related to [s] are in fact homorganic sounds, despite the description of them as heterorganic sounds.

Nasal substitution occurs in many Austronesian languages, with similar correspondences across languages. In certain morphological contexts, words with initial voiceless obstruents appear with a homorganic nasal instead of the obstruent—labial with labial, dental/alveolar with dental/alveolar, velar with velar— so-called nasal substitution (De Guzman, 1978; Pater, 1999, 2001; Blust, 2004), as in Table 1a. For words with initial voiced obstruents, a homorganic nasal surfaces along with the obstruent, Table 1b. Our focus is on the Table 1a pattern, the voiceless obstruents and the corresponding homorganic nasals.¹

What is less straightforward—yet familiar across different languages in this family—is the behavior of word-initial orthographic ‘s.’ Since ‘s’ is typically classed with the other dental/alveolar consonants, we would expect it to pair with [n] in this paradigm. However, it pairs with orthographic ‘ny’ instead of with ‘n,’ illustrated in Table 2 where the nasal correspondent of [s] is represented as [N_s].²

The contrast between the behavior of [s] and the behavior of other voiceless obstruents appears to break the ‘homorganic nasal’ pattern. Our question is whether this is indeed the case, arguing in favor of an abstract pattern, i.e., a relation between two sounds which is not grounded completely in their phonetic properties. The alternative is that the homorganic nasal pattern is concrete, i.e., the relation between the two sounds is fully grounded in their phonetic properties. In an abstract relation, the places of articulation of [s] and of [N_s] would be quite different from each other while if the relation is concrete, the articulation of [s] and [N_s] would be relatively similar to each other. In either case, there remains the question of what the place of articulation is for each of these sounds; possibilities are shown in Table 3.

Under the abstract hypothesis, the two sounds are related morphologically, but the homorganic relation found with other segments does not hold with [s] and its corresponding nasal [N_s]. We expect that the tongue positions of [s] and [N_s] would be quite different from each other, and comparable to the way that heterorganic tongue positions differ from each other. The place of the two sounds might correspond to the perceived place, with [s] homorganic to [t, n] (an dental/alveolar [s]; Dart, 1991) and [N_s] homorganic to [ʨ, ɲ] (Table 3a). Alternatively, [s] might be distinct from [t, n] (e.g., [s] is postalveolar in the phonological analysis of Mester, 1986) or [N_s] might be distinct from [ʨ, ɲ] (Table 3b, c respectively).

Under the concrete hypothesis, articulatory similarity between [s] and [N_s] is driving the alternation. Thus, we expect that [s], like other voiceless obstruents, would be homorganic with its nasal counterpart and their tongue positions quite similar to each other. If [s] and [N_s] are homorganic, they could class with [t, n], with [ʨ, ɲ], or with a third place of articulation (Table 3d, e, f respectively). The abstract and concrete hypotheses are summarized in Table 4.

We set out to answer the “Abstract or concrete?” question and to address the related place of articulation issues based on ultrasound data of speakers of both Sasak and Javanese.

2. Language background

Sasak is the primary local language of Lombok, Indonesia, with speakers estimated at 2 million (Clynes, 1995) and 2.5 million (Marli, 2015). Sasak, along with Balinese, Sumbawa, Malayic, and Chamic, is within the Malayo-Polynesian sub-group Malayo-Sumbawan (Adelaar, 2005). Sasak is described as having four (Jacq, 1998) or five (Austin, 2003) major dialects. (Austin, 2003 reports that the informal names for the dialects relate to how each group pronounces the deictic words for ‘like this’ and ‘like that’: Ngenó-Ngené (central northeast, central east, and central west coasts of Lombok), Menó-Mené (central Lombok), Ngotó-Ngeté (northeastern Lombok), Ngenó-Mené, also known as Kutó-Kuté (north Lombok), and Meriaq-Meriku (south central Lombok). Jacq, 1998 does not include Ngenó-Mené as a dialect.) The dialects with the widest geographical distribution are Ngenó-Ngené and Menó-Mené, which are the only varieties used by Sasak speakers in this study.

Javanese is the most-spoken regional language of Indonesia and the most-spoken language of the Austronesian language family with approximately 75 million speakers. It is found along the northwest coast of Java (Banten, Krawang, Cirebon) and in the central and eastern areas of this island. Outside of Java, it is used in diasporic communities in neighboring provinces of Sumatra, Kalimantan, and Sulawesi, as well as in Suriname and New Caledonia. Three dialects are usually distinguished (western, central, and eastern) (Ras, 1985), and the western dialect is further divided into seven subdialects (Nothofer, 1980). Our participants are all from the central and eastern dialects, which have not yet been studied in much detail (Nothofer, 2006).

Nasal substitution in Sasak appears on verbs “used when the Patient-like argument is non-referential” according to Austin (2013, p. 41). There are many other factors determining the distribution of oral- or nasal-initial verb forms; see Austin (2013). Similarly, in Javanese, nasal substitution appears on verbs and relates to argument structure: Sato (2008, p. 53) calls nasal substitution the ‘active voice morphology’ and shows that it is necessary in basic transitive clauses, but does not occur in Wh-questions or passives. See also Sato (2015); see Herawati et al. (2016) for discussion of nasal substitution and denominal verbs.

As for the sounds, nasal substitution refers to related pairs of words, typically one which begins with a voiceless oral obstruent and the other with a nasal homorganic to that obstruent. (Voiced obstruents, sonorants, and vowel-initial words have their own patterns; see Clynes, 1995 and Austin, 2013 for Sasak; Dudas, 1976; Robson, 1992; and Lee, 2001 for Javanese, and Pater, 1999, 2001 for the Austronesian pattern in general).

To put nasal substitution in context, the Sasak and Javanese consonant inventories are shown in Table 5, based on Clynes (1995); Archangeli et al. (2016) for Sasak³ and Dudas (1976) for Javanese. In these tables, we describe sounds c [ʨ], j [ʥ], ny [ɲ], and y [j] as ‘postaveolar/palatal’ due to the lack of agreement in the literature as to the precise location of constriction described for these consonantal sounds. Both languages distinguish bilabial, postalveolar, and velar consonants. Sasak has a single dental/alveolar category. Javanese has both dental and alveolar consonants (Dudas, 1976 [citing Horne, 1961; Hayward & Mulijono, 1991]), also described as a dental/retroflex contrast (Suharno, 1982; Robson, 1992; Adisasmito-Smith, 2004; Graff & Jaeger, 2009); ‘s’ is classed with dentals by all sources. Javanese nasal substitution is described as resulting in a dental nasal [n̪] regardless of whether the corresponding sounds is a dental [t̪] or an alveolar (or retroflex) [ṯ/ʈ]. Because of the challenges of imaging the tip of the tongue with ultrasound, we did not use stimuli with initial alveolar/retroflex stops in the Javanese study.⁴

Consonant inventories for Sasak (above) & Javanese (below). The consonants that are our focus here are boxed in these tables.

Sasak:	Bilabial		Dental/Alveolar		Postalveolar/Palatal		Velar		Glottal
Plosive	p	b		d			k	ɡ	ʔ
Affricate						ʥ
Nasal		m						ŋ
Trill/Tap				r
Fricative									h
Approximant						j		w
Lateral approximant				l

Javanese:	Bilabial		Dental/Alveolar				Postalveolar/Palatal		Velar		Glottal
Plosive	p	b		d̪	ṯ	ḏ			k	ɡ	ʔ
Affricate								ʥ
Nasal		m								ŋ
Trill/Tap						r
Fricative											h
Approximant								j		w
Lateral approximant						l

The languages are similar in that each has only one sibilant, which is one of the sounds targeted in this study. It is possible that there is more variety of articulation for the sibilant because there is no sibilant contrast to be maintained—e.g., there is no [∫] alongside the [s]. Clynes (1995) classes Sasak [s] together with [ʨ, ʥ]. Mester (1986) views Javanese /s/ as a postalveolar consonant, and Robson (1992) states that the Javanese ‘s’ is similar to that of English, but “sometimes is heard as approaching sh” (p. 12).⁵ We did not perceive this fluctuation ourselves, in either language. These different classifications, along with nasal substitution apparently relating ‘s’ and a palatal nasal, raise questions about the phonetic nature of the sibilant in both languages: Could it be articulated somewhere between an dental/alveolar sound and a postalveolar/palatal sound, or is it indeed postalveolar/palatal? On the other hand, because Sasak has only one contrast in the dental/alveolar region while Javanese has two contrasts for the stops, we might expect concomitant differences between the two languages in the nasal counterparts to [s].

4. Results

In order to determine the significance of the above observations, we carried out LMERs on RMSD differences for various classes of sounds: The RMSD between two tongue splines serves as a measure of similarity of articulatory tongue positiontion. We divided the relevant sound pairs into six categories, shown in Table 11. ‘Homorganic’ refers to sounds with the same place of articulation, dental/alveolar or postalveolar, while ‘heterorganic’ is a cross between these two. These comparisons give a measure for RMSD for homorganic and heterorganic sounds. The ‘ambiguous’ category contains the sounds tested by this study, [s] and [N_s]. ‘Nasality-same’ (nasality_s) means either both sounds are oral or both sounds are nasal; ‘nasality-contrastive’ (nasality_c) means that the two sounds in a pair disagree for nasal/oral articulation.¹⁰

Using the categories from Table 11, we are able to make our predictions explicit. Our first focus is on the categories homorganic and heterorganic, whether oral or nasal. We use the homorganic class to establish reasonable RMSDs for sounds made with the same place of articulation (same or similar articulatory position of the tongue). RMSDs are predicted to be small in this case because homorganic sounds are made with the same place of articulation by definition. In contrast, we expect large RMSDs when the two sounds have different places of articulation, the heterorganic condition. Putting these together, we expect that the RMSD_homorganic is smaller than the RMSD_heterorganic.

When nasality is added in, we expect to find that homorganic sounds with contrastive nasality still have a small RMSD, but it is slightly larger than when the two sounds are truly identical due to differences introduced by the nasal/oral contrast because of the different manners of articulation. Our four expectations are summarized in Table 12.¹¹

The box plot in Figure 4 shows the distribution of RMSDs for both the unambiguous sounds and the ambiguous sounds. Focusing on the unambiguous sounds, we see that the RMSDs for homorganic sounds are small, well below 5 mm, with a lower mean when sounds are identical (i.e., the nasality_s case; Sasak: 2.5 mm, Javanese: 1.6 mm) than when nasality differs (nasality_c; Sasak: 3.4 mm, Javanese: 3.9 mm), exactly as expected: RMSD_Homorganic-s < RMSD_Homorganic-c. (This difference is significant, as seen in Table 14.) In contrast, the means for heterorganic sounds are above 5 mm for both Sasak and Javanese, whether there is a nasality contrast or not, again as expected: RMSD_{Homorganic-s,c} << RMSD_Heterorganic. RMSDs pattern as expected; we now have a measure to use in quantifying comparisons involving ambiguous sounds.

Figure 4

Box plots showing the distribution of RMSD values for unambiguous homorganic and heterorganic pairs and for the ambiguous sounds, whether they have the same or contrasting nasality (same, contrastive respectively). Homorganic sounds with the same oral/nasal value are identical in this table, [t]–[t], [n]–[n], etc.

In particular, we now can understand the abstract/concrete hypotheses’ predictions in terms of RMSD. Under the abstract hypothesis, [s] is heterorganic to [N_s], shown by a relatively large RMSD. Under the concrete hypothesis, [s] is homorganic with [N_s], shown by a RMSD similar to that of homorganic-contrastive pairs since [s] and [N_s] have different nasality values; see Table 13. Under both hypotheses, the self-comparison values (RMSD_Ambiguous-s)—i.e., [s] compared with [s] and [N_s] compared with [N_s]—are expected to be small.

Table 14 evaluates the predictions from Table 13 in terms of estimated RMSD values for different comparisons, using LMERs to make those comparisons. The Place effects show that homorganic sounds have a significantly smaller estimated RMSD than do heterorganic sounds (Sasak same nasality: 2.5 mm < 6.4 mm, p < 0.0001; Sasak contrastive nasality: 3.4 mm < 6.5 mm, p < 0.0001; Javanese same nasality: 1.6 mm < 4.3 mm, p < 0.0001; Javanese contrastive nasality: 3.9 mm < 4.5 mm, p < 0.0001), with a general difference of approximately 3 mm. This is consistent with the prediction for place differences. In contrast, according to the LMER results for both languages, estimated RMSD values for homorganic sounds with same nasality (i.e., [t] compared with [t], [n] with [n], [ʨ] with [ʨ], [ɲ] with [ɲ]) and for ambiguous sounds with same nasality (i.e., [s] with [s], [N_s] with [N_s]) differ by a much smaller margin (Sasak: homorganic_s 2.5 mm > ambiguous_s 2.2 mm, p < 0.0001; Javanese: homorganic_s 1.6 mm = ambiguous_s 1.6 mm, p = 0.354), consistent with the predictions pertaining to ambiguous_same sounds.

LMER estimates of RMSD values (in mm) for unambiguous and ambiguous sound classes in Sasak (top) and Javanese (bottom). “Est. 1” shows RMSD estimates for the lefthand side of each prediction; “Est. 2” shows RMSD estimates for the righthand side of each comparison. The box highlights the p-value that is not significant. Sounds are categorized by place and nasality as in Table 11.

Javanese
	Prediction	Est. 1	Est. 2	S.E.	t-value	p-value
Place	homorganics << heterorganics	1.63	4.29	0.03	104.43	<0.0001
	homorganicc << heterorganicc	2.97	4.54	0.03	62.38	<0.0001
	homorganics = ambiguouss	1.63	1.60	0.03	0.93
Nasality	homorganics < homorganicc	1.63	2.97	0.03	52.48	<0.0001
	heterorganics < heterorganicc	4.29	4.54	0.03	9.75	<0.0001
	ambiguouss << ambiguousc	1.60	6.91	0.04	140.05	<0.0001

Turning to the effect of nasality, we see that the RMSD estimates for homorganic comparisons with the same nasality are smaller than those for homorganic comparisons with contrastive nasality (Sasak: 2.5 mm < 3.4 mm, p < 0.0001; Javanese: 1.6 mm < 3.9 mm, p < 0.0001), although the RMSD value for homorganic_contrastive pairings is still relatively small. Heterorganic_same and heterorganic_contrastive pairings were similar to each other in RMSD estimates but still differed significantly (Sasak: 6.4 mm < 6.5 mm, p = 0.0082; Javanese: 4.3 mm < 4.5 mm, p < 0.0001), and corresponding RMSD values in these conditions were relatively large. Importantly, RMSD estimates for ambiguous sounds with contrastive nasality (ambiguous_c) were large (Sasak: 9.5 mm; Javanese: 6.9 mm) and differed drastically from RMSD esimates for ambiguous sounds with matching nasality (Sasak: 9.5 mm >> 2.2 mm, p < 0.0001; Javanese: 6.9 mm >> 1.6 mm, p < 0.0001). We conclude that [s] and [N_s] exhibit the greatest distinctness in lingual contour shape and place of articulation in both languages, exactly as predicted under the abstract hypothesis.

The answer to the abstract/concrete question raises the issue of whether [s] is dental/alveolar sound and [N_s] is postalveolar, or whether one or the other is something else. In order to test whether [s] and [N_s] are homorganic with other dental/alveolar and postalveolar sounds respectively, we revised our earlier LMER models to target these two ambiguous sounds, including pairwise comparisons between each of the ambiguous sounds [s, N_s] and each of the unambiguous sounds [t, n, ʨ, ɲ] (a separate model was generated for each ambiguous sound, with only relevant sound comparisons included in the data set). The revised models provide RMSD estimates for each sound-sound pair as well as p-values for comparisons with corresponding unambiguous homorganic and unambiguous heterorganic categories given in Table 11, homorganic_s, homorganic_c, heterorganic_s, and heterorganic_c. RMSD estimates and p-values from the revised LMER models are reported in Table 15. The closer the RMSD estimate for a given sound pair is to the RMSD of one of the unambiguous categories, the more likely that that pair is a member of that category. If a p-value indicates that the RMSD comparison for the ambiguous sound does not differ from the RMSD for the corresponding unambiguous homorganic comparison, then the place-ambiguous sound in the pair is homorganic with the other sound in the pair.

Table 15

RMSD estimates in mm (values highlighted in gray) and p-values for comparisons of ambiguous sounds [s, N_s] with unambiguous dental/alveolar and postalveolar sounds. Boxed p-values indicate RMSD differences that are not significant.

			Homorganic comparison			Heterorganic comparison
	Pair	RMSD	Pair	RMSD	p-value	Pair	RMSD	p-value
Sasak	[s]–[t]	2.95	[t]–[t]	2.62	<0.0001	[t]–[ʨ]	6.02	<0.0001
	[s]–[n]	3.64	[t]–[n]	3.25	<0.0001	[t]–[ɲ]	8.13	<0.0001
	[Ns]–[ɲ]	2.55	[ɲ]–[ɲ]	2.52		[ɲ]–[n]	6.70	<0.0001
	[Ns]–[ʨ]	3.86	[ɲ]–[ʨ]	3.59	<0.0001	[ɲ]–[t]	8.13	<0.0001
	[s]–[Ns]	9.49	[t]–[n]	3.31	<0.0001	[t]–[ɲ]	8.13	<0.0001
Javanese	[s]–[t]	1.89	[t]–[t]	1.48	<0.0001	[t]–[ʨ]	3.77	<0.0001
	[s]–[n]	2.93	[t]–[n]	2.53	<0.0001	[t]–[ɲ]	6.30	<0.0001
	[Ns]–[ɲ]	1.90	[ɲ]–[ɲ]	1.97	0.0468	[ɲ]–[n]	4.81	<0.0001
	[Ns]–[ʨ]	3.45	[ɲ]–[ʨ]	3.41		[ɲ]–[t]	6.30	<0.0001
	[s]–[Ns]	6.91	[t]–[n]	2.52	<0.0001	[t]–[ɲ]	6.30	<0.0001

In all comparisons shown in Table 15, the RMSD estimates for [s] compared with either [t] or [n], and for [N_s] compared with either [ʨ] or [ɲ] are similar to the RMSD estimates for corresponding homorganic comparisons (columns 4–6, Table 15) and much smaller than the estimates for corresponding heterorganic comparisons (columns 7–9, Table 15). In general, RMSD estimates for comparisons of [s] to both [t] and [n] and of [N_s] to both [ɲ] and [ʨ] are within the range of homorganic contrasts (a RMSD near 3-mm), rather than in the range of heterorganic contrasts (a RMSD at or above 6-mm). In two cases, comparisons between Sasak [N_s]–[ɲ] and Javanese [N_s]–[ʨ] with their corresponding homorganic pairs [ɲ]–[ɲ] and [ɲ]–[ʨ] result in large p-values (p = 0.618 and p = 0.190, respectively), indicating no significant difference between RMSDs for these specific sound pairs and their unambiguous homorganic analogues. In Javanese, RMSDs for [N_s]–[ɲ] differ significantly from those for the known homorganic pair [ɲ]–[ɲ] (p = 0.0468), though to a lesser extent than for other presumably homorganic comparisons, and the RMSD estimate (1.9 mm) is even smaller than most other homorganic RMSDs. These relations are shown visually in Figure 5, in which presumed homorganic pairings, [s]–[t], [s]–[n], [N_s]–[ɲ], and [N_s]–[ʨ] (middle and leftmost orange shapes in each plot), are more similar to corresponding homorganic-same and -contrastive groups (gray shapes) than their heterorganic-same or -contrastive counterparts (green shapes) in terms of mean RMSD between contours. In each case for both languages, the comparison between [s] and [N_s] (rightmost orange shapes) has a larger mean RMSD value that any other homorganic or heterorganic comparison.

Figure 5

Violin plots with overlaid box plots for RMSD values (in mm) for each group in the revised LMER models in Table 15. RMSDs for [s]- and [N_s]-containing pairs (column 2 in Table 15) are highlighted in orange, whereas homorganic pairs (column 5, Table 15) are indicated in gray and heterorganic pairs (column 8, Table 15) are shown in green. In each plot, probability density of a given RMSD is indicated by the cross-sectional width of the outer shape at that value, interquartile ranges are indicated with box plots within each shape, and median values are indicated by the horizontal line in each box plot.

These results are consistent with the dental/alveolar/postalveolar hypothesis, that, in both languages, [s] is a member of the known dental/alveolar class along with [t] and [n] and that [N_s] is a member of the postalveolar/palatal class along with [ʨ] and [ɲ].

5. Discussion

Comparison of lingual contours in ultrasound images for the relevant sounds shows that in these languages, the nasal substitution pattern relating a voiceless obstruent with its homorganic nasal stop breaks down with [s] and [N_s]. As illustrated by the contour plots and Smoothing Spline ANOVAs (SS-ANOVAs, Davidson 2006)¹² for S2 in Figure 6, these two sounds have different articulations: [s] is an anterior, dental/alveolar sound in both Sasak and Javanese, with an articulation similar to that of [t] and [n], while [ɲ]—whether related to [s] or to [ʨ]—is a postalveolar sound like [ʨ]. This pattern is borne out across all talkers in both languages. Given the morphological pairing of [s] with [ɲ] and the attested variation among possible articulations for [s] sounds (Dart, 1991), we would not have been surprised to find a postalveolar [s] in these languages, with an articulation more similar to [ɲ]. However, this is not the case, nor is it the case that [s] and [N_s] share a single articulatory configuration that contrasts with both dental/alveolar and postalveolar consonants. Instead, there is an abstract morphophonological relation between an dental/alveolar [s] and derived postalveolar/palatal nasal [ɲ], just as impressionistic accounts lead us to expect.

Figure 6

Aggregated tongue splines (left) and SS-ANOVA by sound (right) for Sasak participant S2. The width of lines in the SS-ANOVA plot corresponds to a 95% Bayesian confidence interval for radius r at each value of θ for each sound’s lingual contours. In the upper figures, unambiguous dental/alveolar splines are black; in the lower figure, unambiguous postalveolar/palatal splines are orange. In all figures, ambiguous splines are blue for [s] and green for [N_s]. Note that the SS-ANOVA contour for [ɲ] for this speaker lies completely underneath the contour for ambiguous nasal [N_s].

Further examination of the splines and SS-ANOVAs provides a better understanding of the articulation of these consonants in the two languages. Reviewing these images shows that nearly all talkers (10 out of 11 Sasak, 8 out of 8 Javanese) articulated postalveolar sounds [ʨ] and [ɲ] as seen in Figure 6—with somewhat dissimilar articulatory positions: [ʨ] was articulated with a tongue-blade constriction posterior to dental/alveolar [t, s, n] but without full raising of the tongue body to the hard palate, whereas [ɲ], whether derived from [ʨ] or [s], was articulated similarly with the tongue blade but with a complete palatal occlusion between the tongue body and hard palate, at or slightly anterior to the constriction locations for palatal sounds [j] and [i] in the two languages. Thus, [ɲ] in Sasak and in Javanese is characterized as having a longer region of palatal constriction than [ʨ], and this articulation is consistent with that observed in electropalatalographic data for Peninsular Spanish alveolo-palatal ñ [ɲ] (Martínez Celdrán & Fernández Planas, 2007; Fernández Planas, 2009; Shosted et al., 2012).

These articulator relations align most closely with the first abstract, heterorganic hypothesis in Table 3a, and are summarized as in Table 16. Furthermore, we see that not only is the relation between [s] and ‘N_s’ abstract, so too is the relation between [ʨ] and [ɲ]: They are not entirely homorganic sounds.

That these articulatory patterns obtain in a pair of related languages suggests that the anomalous pairing of [s] and [ɲ] with respect to nasal substitution is stable, despite being an abstract linguistic relation. The pairing appears to have resisted pressure to move towards a concrete relation that would, over time, serve to regularize the pattern. Archangeli et al. (2012) find the same sort of stability in Bantu vowel harmony: Bantu height harmony occurs primarily in verbs, where sequences of mid vowels are preferred to mid-high sequences, with the exception of the permitted sequence [e…u]. The same pattern is found in nouns to a lesser degree—with the exception that even [e…u] occurs less often than expected. The difference is that in verbs, the [e…u] sequence arises across a morpheme boundary, and so any changes in this sequence disrupt an entire morphological paradigm while with the nouns, gradual item-by-item change is possible. To recast Archangeli et al. (2012) in terms of the current discussion, every nasal substitution form relating [s] and [ɲ] constitutes pressure against reanalyzing any single instance relating [s] and [ɲ]. Such pressure predicts that anomalous patterns that enter a morphophonological relation (through whatever means) are likely to remain in a language.

In addition to finding a lack of within-paradigm regularity in our study (the concrete-homorganic hypothesis in Table 3d–f), we also find little evidence of even partial assimilation. Although [s] is clearly articulated in the dental/alveolar region with the tongue tip/blade, we do not observe articulations of its nasal counterpart ([N_s]) that are more similar to that of [s] than would be expected from a palatal nasal sound. Comparisons between [N_s] and [ɲ] result in similar RMSD values (or smaller, in the case of Javanese) than comparisons within [ɲ] contours alone, indicating that [N_s] is no different from [ɲ] than other productions of [ɲ]. Thus, it is not the case that [s] as a derivational source of [N_s] influences that articulation of its nasal substitution counterpart with its anterior, apical/laminal articulation, and in fact the RMSD values between [s] and its nasal counterpart [N_s] are among the largest values observed in the entire data set for each language.

This work uses RMSD calculations to determine whether two sounds are homorganic or heterorganic in articulatory place, giving a quantified comparison of tongue-contour data from ultrasound images. RMSDs provide individual numerical values to represent the magnitudes of spatial difference within each contour comparison, and these values can be used for further comparison. Moreover, when coupled with a mixed-effects linear regression model, RSMD values from multiple talkers can be compared within a single analysis by treating Speaker as a random effect. This kind of comparison enables us to identify patterns that hold generally across speakers of a given language. Statistical comparisons of RMSD values across test conditions of interest allow for an evaluation of similarity or difference between those conditions, adding to the similarity tools proposed in Mielke (2012).

6. Conclusion

To conclude, this study has shown that there is an abstract morphophonological relation in the nasal substitution paradigm in both Sasak and Javanese. Our analysis of ultrasound images supports [s/ɲ] nasal substitution as an abstract relation within what appeared to be an otherwise general and concrete homorganic pattern: We show that in both languages, [s] is articulated quite similarly to the dental/alveolar sounds and that the morphologically-related [N_s] is indistinguishable from [ɲ]. Further examination of the data shows that the voiceless affricate is alveolo-palatal [ʨ], which corresponds to palatal [ɲ] in the same paradigm, again an abstract relation. Thus, the pattern is not as homorganic as impressionistic analysis suggests. We suggest that the pattern has resisted regularization because it is a robust morphophonological relation, held in place by morphological paradigm pressure.

Finally, we introduce the RMSD/LMER method for comparing tongue contours, pooling comparisons from multiple subjects in order to better understand general patterns within each language.

Competing Interests

The authors have no competing interests to declare.