2.1. Velar nasal plus

It should be pointed out that post-nasal [ɡ] was once present across all varieties of English, before it began to undergo deletion in the Late Modern English period. Bermúdez-Otero and Trousdale (2012), drawing upon reports by eighteenth-century orthoepist James Elphinston as discussed by Garrett and Blevins (2009), provide a particularly enlightening account of this change. They show how the phonological /ɡ/-deletion rule progressed through the grammar such that in varieties of Present Day English, [ŋɡ] clusters are only ever present pre-vocalically in monomorphemic or root-based items such as finger or elongate, in addition to a small set of lexically-listed exceptions (the comparative and superlative forms of strong, long, and young).

Although this coda-targeting deletion rule ran to completion in most varieties of English, the non-coalesced [ŋɡ] form was not lost everywhere; variation in (ng) still exists today in these varieties spoken in the North West and West Midlands of England. Although we know very little about the synchronic variation of (ng) in these communities, the presence of post-nasal [ɡ] is well-documented in the dialectological literature (e.g., Hughes et al., 2012; Trudgill, 1999; Wakelin, 1984). It has been documented in Birmingham (Thorne, 2003), Cannock (Heath, 1980), Liverpool (Knowles, 1973), West Wirral (Newbrook, 1999), Manchester (Bailey, 2015; Schleef, Flynn, & Ramsammy, 2015), and in Sandwell and the surrounding Black Country (Asprey, 2015; Mathisen, 1999). These areas all fall within the North West or West Midlands of England, corresponding with the Survey of English Dialects isogloss (Orton, Sanderson, & Widdowson, 1978) as well as more recent dialectological surveys (MacKenzie, Bailey, & Turton, 2017). However, these studies do not go beyond pointing out the presence of this form, and many in fact do not acknowledge that its presence is variable in those communities in which it is attested, let alone explore the factors that condition such variation. With many of them also relying on impressionistic and auditory analysis, variation in (ng) has simply not been subject to the same sociophonetic scrutiny as other variables.

While variation in (ng) does historically stem from a deletion rule, it is possible that at this point in time the synchronic system does not work that way, and that some tokens of post-nasal [ɡ] surface instead from an insertion process. Determining whether or not this is the case is beyond the scope of this paper, and as such the subsequent discussion of (ng) variation will remain theory neutral, referring only to presence or absence of [ɡ] and not to the process assumed to underpin this variation.

The observation that [ɡ]-presence is favoured before pause, with which this paper is primarily concerned, has not been discussed explicitly in other studies. However, the observation that (ng) shows strong stylistic stratification could provide supportive evidence for this effect; both Mathisen (1999) and Bailey (2015) report high rates of [ɡ]-presence in word-list elicitations. The conventional and most immediate interpretation of this is of course that [ɡ]-presence is considered the ‘prestige’ form and that this style-shifting simply reflects adherence to this norm in more conscious speech styles. However, it should be noted that these word-list elicitation tasks conflate two things: formality, and phonological environment. In other words, do we find more [ɡ]-presence in word-list elicitations because this form is considered the standard and is therefore more frequent in formal discourse styles, or is it actually because in this style the tokens of (ng) are elicited with clear pauses and prosodic breaks between each item? It is of course possible that the high rate of word-list [ɡ]-presence is in fact attributable to both. The former explanation presupposes that forms with the post-nasal [ɡ] are indeed considered prestigious, but the only study to investigate the evaluation of [ŋɡ] shows no evidence that this is the case (Newbrook, 1999).

A number of studies seem to suggest that the local non-coalesced form, in which post-nasal [ɡ] is present, is increasing in popularity with younger speakers, though few actually provide quantitative evidence in support of such claims. Asprey (2007, p. 90) reports that the presence of [ɡ] is “linked to the younger generations” in the Black Country, and this association between [ŋɡ] and youth speech is echoed by others (see Chinn & Thorne, 2001; Wakelin, 1984). Mathisen’s (1999) work in Sandwell in the West Midlands does, however, provide an empirical grounding to such claims; this increase, described as a ‘revitalization’ of this local form, is being led by young women and the working classes in particular. A preference for velar nasal plus among the working classes is corroborated by Thorne (2003, p. 121), and an increase in its use in apparent time is also found in the speech community of Wilmslow, Cheshire (Watts, 2005, p. 173).

2.2. Boundary effects on other external sandhi processes

Since very little work has been carried out on the language-internal factors influencing (ng), specifically its sensitivity to phonological and prosodic environment and its behaviour pre-pausally, we can instead turn to comparable external sandhi processes that have been subject to more extensive variationist study. One such example is /t,d/-deletion in varieties of English: the reduction of word-final consonant clusters ending with a coronal stop e.g., just [dʒʌst]∼[dʒʌs], proved [pɹuːvd]∼[pɹuːv]. This is remarkably well-studied, having been attested across the world’s varieties of English, and its variation shows similar patterning to (ng). Both involve segmental presence/absence in word-final consonant clusters, and both are sensitive to morphological and syntactic structure in ways consistent with a cyclic analysis. Guy (1991) adopts a Lexical Phonology framework in accounting for the morphological effect on /t,d/-deletion, whereby deletion is less likely for past tense items due to the targeted /t,d/ segment appearing later in the derivation, while diachronic and synchronic accounts of (ng) have been combined under the life cycle of phonological processes (see Bermúdez-Otero & Trousdale, 2012 on the diachronic process of /ɡ/-deletion, and Bailey, 2016b on the synchronic implications that follow from this analysis).

Most importantly for the present study, both processes show sensitivity to the immediate phonological context and do so in an identical manner: [ɡ]-presence is more likely pre-vocalically than pre-consonantally (Knowles, 1973; Upton, Sanderson, & Widdowson, 1987; Watts, 2005), and the same pattern of variation has been shown for /t,d/-deletion in countless studies (e.g., Tamminga, 2016 on Philadelphia English, Baranowski & Turton, 2015 on Manchester English). In fact, Tagliamonte and Temple (2005) claim that this is consistently the strongest predictor of /t,d/-deletion in all varieties of English in which it has been studied. What is not so consistent, however, is how coronal stop deletion behaves pre-pausally. In some varieties, following pauses are said to inhibit deletion even more so than following vowels, e.g., York (Tagliamonte & Temple, 2005), Philadelphia (Guy, 1980), and Chicano English (Santa Ana, 1996), while in others the deletion rate pre-pausally is higher (see Bayley, 1994 on Tejano English and Hazen, 2011 on Appalachian English). For some speakers, particularly those of African American Vernacular English, deletion in pre-pausal environments can be even as high, and sometimes higher, than in pre-consonantal position (e.g., Fasold, 1972 in Washington D.C. and Guy, 1980 in New York).

More recent studies have done away with a categorical coding of pause presence/absence altogether, and instead incorporated pause duration as a gradient factor; Tanner, Sonderegger, and Wagner (2017) show how pause duration, used as a proxy of boundary strength, modulates the effect of following segments such that the influence of a following vowel or consonant on the application of /t,d/-deletion is neutralized when a long pause (100 ms or greater) separates them from the preceding /t,d/ cluster. They argue that this behaviour lends empirical support to the production planning hypothesis (Wagner, 2012): The stronger the prosodic or syntactic boundary between constituents, the less likely it is that the following segmental material has been planned, and as such it can have no effect on the realization of the preceding coronal stop. This has also been recently explored by Tamminga (2018), who finds a similar interaction between the magnitude of the following segment effect and the strength of the syntactic juncture between the target and trigger.

Formal accounts of external sandhi conditioning, specifically the mechanisms that trigger this sensitivity to phonological environment, have also often focused on /t,d/-deletion. A number of explanations of the ‘following segment effect’ have been proposed, with the goal of capturing not just the consistent observation that deletion is more likely pre-consonantally than pre-vocalically, but also the variability of deletion pre-pausally. It has been argued (e.g., Guy, 1980) that the effect stems from the possibility of phrase-level resyllabification, where word-final pre-vocalic /t,d/ variably attaches as an onset to the following word and thus avoids deletion; however, this has been disputed on the grounds that the phonetic realization of word-final pre-vocalic /t,d/ when present on the surface is not comparable to that of a canonical word-initial /t,d/ even though the former is argued to be in onset position (Labov, 1997).

Alternative explanations make reference to the Obligatory Contour Principle (J. J. McCarthy, 1986; Yip, 1988) by highlighting differences in feature similarity between the /t,d/ and a following consonant, liquid, glide, or vowel. Crucially, the inter-dialectal variation in how /t,d/-deletion behaves pre-pausally stems from the fact that the pre-pausal environment by its very nature does not fit into the above hiearchy and is therefore “susceptible to differing analyses by different speakers or dialects” (Guy, 1980, p. 27).

Coetzee (2004) offers yet another proposal, instead relying on licensing by cue (Steriade, 1997) and how these perceptual cues for identifying the place and manner of articulation of stops (namely, their release and also the formant transitions into a following vowel) are realized before consonants, vowels, and pauses. Such an account simply has to stipulate inter-dialectal differences in the ranking of constraints, or alternatively in the phonetic realization of pre-pausal consonants, to capture the difference between varieties in how pre-pausal /t,d/ behaves. Whatever the nature of this sensitivity to the phonological environment, there is ample evidence to suggest that the effect of a following pause on /t,d/-deletion is open to differing analyses between speech communities. We find similar inter-dialectal variation in /s/-weakening across varieties of Spanish; this rule is yet another example of a coda-targeting lenition process, in this case debuccalization from /s/ to [h], where the effect of a following pause is not universal. In standard varieties of Argentinian Spanish, /s/-weakening is blocked pre-pausally (see Kaisse, 1996), contrasting with Caribbean varieties where weakening shows no such sensitivity to pause (see Harris, 1983).

These processes are uncontroversially leniting and therefore any comparison with (ng), which as discussed earlier could conceivably be a case of synchronic [ɡ]-insertion, should be taken with some degree of caution. However, it remains the case that there are clear parallels between these three processes with respect to their phrase-level conditioning: The varying segments ([ɡ], [t]/[d], and [s]) are present before vowel-initial words, absent before consonant-initial words, and show unusual and inconsistent behaviour pre-pausally. In the case of (td)-deletion and (s)-weakening, this registers itself as differences in pausal effects between different varieties, and in the case of (ng) as diachronic instability, as will be illustrated in Section 4.1.

2.3. Pre-boundary lengthening

One often over-looked aspect of how pauses influence variable linguistic phenomena is the way in which they affect suprasegmental features, specifically phonetic duration. It has been observed cross-linguistically that segments in pre-boundary position are longer in duration than those not adjacent to a prosodic boundary. Many reports focus on Indo-European languages (see Lehiste, Olive, & Streeter, 1976 on English; Lindblom, 1968 on Swedish; Delattre, 1966 on French, Spanish, and German), but Hockey and Fagyal (1998) also report it for Hungarian of the Finno-Ugric family, despite this language having phonemic length distinctions.

It is generally considered that pre-boundary lengthening is triggered directly by finality in a prosodic constituent, with the magnitude of lengthening correlated with the size of the constituent in the phonological hierarchy (Gussenhoven & Rietveld, 1992; Wightman, Shattuck-Hufnagel, Ostendorf, & Price, 1992). However, this has recently been disputed by Feldscher and Durvasula (2017), who instead propose that lengthening is triggered directly by pause. There is also evidence indicating language-specific implementations of lengthening, possibly influenced by the role of duration in other areas of the grammar, which suggests that the magnitude of pre-boundary lengthening is sensitive to factors other than just the prosodic hierarchy (Cho, 2016; Turk, 2012). The exact typology of constituents within this hierarchy is also subject to debate, but there is widespread agreement on the ‘major’ categories above the word-level, as well as their relative ordering: The Utterance (U) is higher than the Intonational Phrase (IP), which in turn is higher than the Phonological Phrase (PPH) (Gussenhoven, 2002; Selkirk, 1978).

Given that stronger boundaries elicit longer pauses and greater segmental lengthening, the collinearity between these three factors raises questions regarding the nature of these reported ‘pre-pausal’ effects. What if the effects of a following pause sometimes reflect something more granular, i.e., sensitivity to duration? This was explored by Sproat and Fujimura (1993) in their study of /l/-darkening; they argue that contrary to earlier claims, /l/-darkening is gradient in nature and triggered by a purely durational mechanism in which the darkness of the /l/ is positively correlated with the duration of the rime. Although more recently it has been shown that this is an oversimplification, with ultrasound tongue imaging revealing both a categorical and gradient process of darkening (see Turton, 2014, 2017), it is nevertheless the case that the gradient process of darkening is correlated with duration.

Much like with the parallels drawn between (ng) and (td) in the preceding section, I do not mean to suggest that (ng) and /l/-darkening are comparable variables; this is particularly important in the case of /l/ given that it is not only uncontroversially leniting but also of a non-deleting type. However, regardless of the similarities and differences between these processes, it is possible that the same durational mechanism applies in the case of (ng), even if it is interpreted as insertion. Given that such an insertion process only requires a slight change in gestural timing, where the velum is raised before rather than after cessation of the oral gesture, it would hardly be surprising to find it showing sensitivity to the preceding nasal duration.

2.4. Research questions

In light of the current knowledge summarized in the previous section, this study aims to accomplish two things: to provide evidence of a hitherto-unreported change in progress towards increasing [ɡ]-presence among young speakers, restricted to pre-pausal contexts, and then to solve the collinearity between various boundary phenomena by investigating three related prosodic factors that potentially condition this change.

Solving this collinearity issue has wide implications for a number of theoretical approaches that make predictions with respect to what should condition such an effect. A classical Prosodic Phonology approach to external sandhi processes (Nespor & Vogel, 1986) predicts that the conditioning environment is defined by the categories of the prosodic hierarchy itself, e.g., when final in the intonational phrase (IP) or utterance (U). If this were the case, we should find a stark contrast in [ɡ]-presence between domain-medial and domain-final positions, and a result in which this dichotomy provides the best fit to the observed variation would lend support to this theory.

On the other hand, there are theories of lenition (e.g., Lavoie, 2001) that highlight the importance of durational factors over the abstract categories proposed by Prosodic Phonology. These accounts claim that the primary phonetic manifestation of weakening is shorter segmental duration; as such, they would predict that it is phonetic duration that directly influences [ŋɡ] variation, such that the probability of [ɡ]-presence is correlated with the duration of the syllable coda or rime.

Finally, recent years have seen a rise in theories that emphasize the psycholinguistic processing of language, such as the Production Planning Hypothesis (Wagner, 2012); under these accounts, the most important factor in conditioning external sandhi processes is the temporal relationship between target (in this case, word-final [ŋɡ]), and trigger (the following consonant-initial word), thus motivating the inclusion of intervening pause duration in this analysis. It may be the case that this plays the biggest role in conditioning this case of external sandhi, whereby the presence (and possibly duration) of a pause following the (ng) token has a direct impact upon the probability that the [ɡ] is present on the surface, independent of prosodic position or phonetic duration.

It is important to consider these three factors separately at both the conceptual and empirical level, despite the strong collinear relationship between them. Although it has been shown that pause is the most important acoustic cue to the perception of intonational phrasing (see Mo, 2010; Swerts, 1997; Yang, Shen, Li, & Yang, 2014; Zhang, 2012), it is not mandatory to mark a boundary with pause (Krivokapić & Byrd, 2012), which results in cases where this collinearity breaks down. In showing how the effects of pause interact with prosodic position in Japanese high-vowel devoicing, Kilbourn-Ceron (2017) highlights the importance of teasing apart such factors for variables that show apparent ‘pre-pausal’ behaviour, and there is evidence from Argentinian Spanish that (a) IP boundaries can be produced without pause and (b) pauses can occur within IPs (Kaisse, 1996).

This paper seeks to uncover the relative contributions made by these three boundary phenomena (prosodic boundary strength, segmental duration, and pause presence/duration) in boosting [ɡ]-presence in northern British English, and by doing so will contribute to our knowledge of how external sandhi processes operate in pre-boundary position.

4.1. Change in apparent time

Although there have already been reports that rates of [ɡ]-presence are increasing in a number of communities, summarized earlier in Section 2.1, the interaction between age (or date of birth) and phonological environment with respect to [ɡ]-presence has yet to be investigated. Figure 3 plots the pre-consonantal and pre-pausal rates of velar nasal plus by date of birth for this sample of speakers from the North West of England, where ‘pre-pausal’ refers to tokens followed by a period of silence lasting around 100 ms or longer. The results indicate that the increase in [ɡ]-presence over the 91-year time span covered by this sample of speakers is largely confined to the pre-pausal environment.

Figure 3

Change in apparent time of pre-pausal [ɡ]-presence, based on a sample of 32 speakers. Pre-consonantal rates given for comparison. Points reflect individual speaker means; lines reflect linear models fit to the two environments with shaded areas representing 95% confidence intervals.

It should be noted that there also seems to be a slight increase in [ɡ]-presence pre-consonantally, but this trend is much less dramatic and the correlation is not statistically significant (Spearman’s r_s = 0.23, p = 0.21); the trend in pre-pausal environments, however, is strong and highly significant (r_s = 0.70, p < 0.001).⁴ The favourable effect of a following pause on the probability of [ɡ]-presence is particularly evident for speakers born after 1975, many of whom show categorical use of the local form in this particular environment.

This apparent diachronic change affecting pre-pausal velar nasal plus finds statistical support from the results of mixed-effects logistic regression, where the interaction between phonological environment and date of birth is significant for the pre-pausal tokens but does not pass the threshold for significance pre-consonantally (see Table 2). Furthermore, conducting an ANOVA comparison between nested models confirms that adding an interaction with date of birth leads to a statistically-significant decrease in AIC (935.31, cf. 958.29; p < 0.001) and, therefore, a better fitting model.

4.2. Elicitation task

Although there are a number of benefits to analyzing the conversational data discussed in the previous section, most notably the fact that this is a naturalistic speech style and therefore more representative of the speakers’ vernaculars, it is not without fault. One particular limitation is that a dichotomy between whether or not a token of (ng) is followed by a pause actually conflates a number of prosodic environments and interactional situations; in reality, these pre-pausal tokens may encompass a wide range of contexts, e.g., turn-final, utterance-final, IP-final etc. Is there an absence of segmental material following the (ng) token because the speaker was interrupted, or was the pause just temporary, with the speaker then resuming their turn? Pauses may arise for a number of different reasons, whether they be cognitively or interactionally motivated (see Kendall, 2013 for an exploration of the factors that condition pause production).

To combat this shortcoming, the second part of this study’s analysis focuses on the follow-up elicitation task where the exact environments in which (ng) clusters appear can be carefully controlled using reading passage stimuli. In this way, efforts can be made to disentangle the collinearity between the three factors that on the surface appear to be boosting [ɡ]-presence: phonetic duration, prosodic boundary strength, and pause presence/duration.

Figure 4 illustrates an interaction between boundary strength and following segment with respect to rates of [ɡ]-presence. When the (ng) cluster is pre-vocalic, rates of [ɡ]-presence remain high irrespective of the type of boundary; however, in pre-consonantal position the variation clearly shows sensitivity to boundary strength in a much more striking manner, such that the rate of [ɡ]-presence in the weakest boundary context is as low as 4%.

Figure 4

Rate of [ɡ]-presence by boundary strength and following segment.

The relative lack of variation pre-vocalically is no great surprise, and is likely due to the fact that there are two competing forces promoting the presence of [ɡ] in this environment: one that favours [ɡ]-presence before stronger boundaries, as we can see with the pre-consonantal tokens, but also one that favours [ɡ]-presence in weaker boundary contexts; crucially, this latter effect is confined to the pre-vocalic environment. If we assume that variation in (ng) is derived from a coda-targeting deletion rule, and that the promoting effect of following vowels on the probability of [ɡ]-presence stems from phrase-level resyllabification of the [ɡ] into onset position, it logically follows that this effect is more likely when the juncture between the words is weaker.⁵ Because weaker boundaries favour resyllabification, they consequently also favour [ɡ]-presence, but crucially this applies only in pre-vocalic environments. These two antagonistic effects cancel each other out pre-vocalically, where rates of [ɡ]-presence are high across the board, whereas in pre-consonantal environments only the former, more general effect is present. Given then that (ng) only shows sensitivity to boundary strength in pre-consonantal environments, the subsequent analysis will focus on this subset of the data, discarding the pre-vocalic tokens that are largely invariable.

In the pre-consonantal environment, we do clearly see a monotonic increase in [ɡ]-presence correlated with the strength of the following juncture. However, the rates of [ɡ] do not increase in a gradual manner parallel to the phonetically-gradient relationship between boundary strength and segmental duration; instead, we see a stark contrast between boundaries 1–3 and 4–5, suggesting that the meaningful contrast is between IP-medial and IP-final position. However, sensitivity to IP boundaries alone would not account for the contrasting behaviour of (ng) clusters between boundaries 4 and 5; in the former (utterance-medial IP boundary) we see 53% [ɡ]-presence, whereas in the latter (utterance-final IP boundary) we find rates almost at ceiling level (96%).

Pause presence/duration provides a possible explanation for this contrast, in addition to showing the strongest correlation with the presence of post-nasal [ɡ]. The use of [ŋɡ] is more variable at the utterance-medial IP boundary (i.e., boundary 4) because here the prosodic phrasing and, in particular, presence of pause is also variable (cf. the utterance-final IP boundary which is always pre-pausal). This is shown in Figure 5, which illustrates the relationship between pause duration, pre-boundary lengthening, IP position, and the realization of (ng).

Figure 5

The relationship between sonorant duration, following pause duration, and [ɡ]-presence for pre-consonantal (ng) tokens. Tokens with no period of silence before the following word are excluded. Ellipses represent 95% confidence intervals for tokens with and without surface [ɡ]-presence.

What is perhaps most interesting to note from Figure 5 is that there is much clearer separation along the x-axis than along the y-axis with respect to [ɡ]-presence. In other words, following pause duration is a much stronger predictor than sonorant duration, with a cut-off point around 4.6 (∼100 ms) on the x-axis, where any pause longer than this is enough to result in [ɡ]-presence. Reassuringly, this is the same value as the cut-off point used to identify pre-pausal tokens in the conversational data, when establishing the change in progress as described in Section 4.1.

To investigate the effects of pause and IP position independently, there need to exist tokens of (ng) where the pausal cue to major prosodic boundaries is absent on the surface. Figure 5 highlights an overlap between the IP-medial and IP-final tokens with respect to the following pause duration, suggesting that this is the case. In total, 65 of 120 tokens in the IP-final context surface without a pause. However, it is entirely possible that the intonational phrasing this stimuli intended to elicit was not actually produced, and these cases of IP-final tokens without pause are in fact medial in the IP. To combat this, we need independent evidence, specifically based on the pitch contour, of the presence of IP boundaries. Intonational analysis, combining visual inspection of the pitch contours with manual ToBI annotation, reveals that none of these 65 tokens show convincing evidence of a prosodic boundary after the (ng) word.

However, the ability to tease apart these two collinear effects does not rest solely on the presence of such tokens, where IP boundaries are not marked by pause. If there are cases of IP-medial tokens that are followed by pause, and crucially exhibit [ɡ]-presence, this would provide strong evidence that the variation is conditioned most strongly by pause as apposed to the presence of a prosodic boundary. Twenty-five of the 360 tokens (∼7%) elicited in the IP-medial context are produced in such a way. Based on the intonational analysis, 14 of these 25 (56%) are genuinely in IP-medial position with no evidence of pitch reset or boundary tone, i.e., there is a brief juncture before resumption of the same pitch movement. An example of this is given in Figure 6a. It is also important to note that in this example, the hiatus in the pitch contour does not reflect devoicing of the /ɡ, b/ sequence in Spring began but rather a genuine period of silence, as shown in the waveform and spectrogram. A counter-example is presented alongside this in Figure 6b, where the pause is clearly a phonetic cue to an IP boundary tonally marked with a fall-rise phrase accent and boundary tone combination. Crucially, post-nasal [ɡ] is present in all of these 14 genuine cases where (ng) occurs before an IP-medial pause.

Figure 6

Pitch contours and ToBI annotation for two pre-pausal tokens in the IP-medial context: one genuinely IP-medial in (a) and one produced with phrase-final intonation in (b).

Mixed-effects logistic regression lends further support to the idea that the presence and duration of pause is the primary conditioning factor of (ng). Three individual models were initially fit, including a main predictor of either: (1) sonorant duration, (2) IP position (based on what was actually produced, rather than what was intended by the stimulus), or (3) following pause duration, in addition to random intercepts of speaker and word. These models were compared for ‘goodness of fit’ based on their AIC values to determine which predictor explains most of the variation in (ng), where lower values correspond to a better model. These comparisons, summarized in Table 3, indicate that sonorant duration explains the least amount of variation (AIC: 562), and that IP position fares a little better (359). Pause duration (273) is by far the strongest predictor.

Models were then fit with a combination of these predictors to investigate the possibility of additive effects, which could be the case if (ng) is conditioned by multiple phonetic cues to boundary strength. ANOVA comparisons between nested models were conducted to quantify whether or not the increase in the amount of variation explained by these additional predictors offsets the cost of a more complex model. In doing this, it became apparent that the strong predictive power of pause duration does not mean that the other collinear variables play no role; adding IP position to a model with pause duration leads to a decrease in AIC that, although small, is statistically significant (267.44, cf. 272.69; p = 0.007). The fact that IP position explains a significant portion of the remaining variation suggests that (ng) is not only sensitive to pause but also to the prosodic phrasing. That is, although the probability of [ɡ]-presence is most strongly influenced by pause, it is also boosted when final in an intonational phrase. This best-fitting model is given in full in Table 4.

5.1. Mechanisms of innovation

Having successfully ‘disentangled’ the collinearity between what on the surface appeared to be effects of nasal duration (with increasing [ɡ]-presence after longer nasals), prosodic position (with more [ɡ]-presence IP-finally), and following pause (with higher rates of [ɡ]-presence pre-pausally), the results indicate that this innovation in (ng) is conditioned most strongly by the presence/duration of a following pause. This would of course suggest that the apparent relationship between post-nasal [ɡ]-presence and sonorant duration is indirect and stems only from the fact that segmental duration is increased pre-pausally. There is limited evidence to suggest that (ng) is also directly sensitive to prosodic boundary strength; IP position explains a small amount of variation independently of pause, but comparisons between these two predictors suggests that this effect is much smaller in magnitude.

The important role of pause is perhaps best visualized abstractly, as in Figure 7. There is naturally a great deal of overlap between pre-pausal tokens and IP-final tokens, given that the presence of a following pause is one of the major phonetic cues to prosodic boundaries; these tokens that are both IP-final and pre-pausal exhibit post-nasal [ɡ] almost without fail. The non-overlapping portion of Figure 7 reflects the existence of tokens that are pre-pausal but actually medial in the IP; the fact that in these cases [ɡ] is still ever-present provides strong evidence to suggest that only pause is necessary for [ɡ] to surface in these environments, regardless of the prosodic structure.

Figure 7

Visualization of the distribution of pauses and IP boundaries in this study’s dataset, and the effect they have upon [ɡ]-presence.

That this innovation seems to be conditioned most strongly by the presence/absence of pause, rather than by segmental duration or prosodic boundary strength, is rather interesting in light of previous studies that have also attempted to tease apart these factors for other external sandhi processes, e.g., /s/-debuccalization in Spanish. Kaisse (1996) shows how in the Buenos Aires variety of Argentinian Spanish, word-final coda /s/ does not weaken to [h] when the following segment is ‘temporally distant,’ i.e., /s/ is saved from weakening when in pre-pausal position. Much like the argument presented here for (ng) variation, Kaisse claims that this blocking of debuccalization is triggered on the temporal domain, and is independent of prosodic position; this claim is based on the fact that IP-final tokens in fast speech, where the speaker does not pause, still undergo weakening, and that IP-medial tokens where the speaker pauses before resuming with the same intonational contour do not undergo weakening. Comparisons are also drawn with final /r/-devoicing in Turkish, which shows similar behaviour in that devoicing only occurs IP-finally if the IP boundary is marked by a pause (Kaisse, 1990).

More recently, it has been shown that other processes exhibit rather more complex behaviour in pre-boundary environments. Kilbourn-Ceron (2017) investigates the conditioning of high vowel devoicing (HVD) in Japanese and addresses the same collinearity issue highlighted in this paper; the results indicate that all three boundary phenomena play a joint role in conditioning HVD, with an interaction between prosodic position and pause presence such that pauses inhibit HVD phrase-medially but promote it phrase-finally. These results paint a much more complex picture relative to earlier claims that suggest the pre-boundary effect is triggered in utterance-final position (Kondo, 1997).

No other putative pre-pausal effects have, to this author’s knowledge, been investigated from this perspective; however, this interplay between prosody, pause, and segmental duration does raise questions about the nature of similar effects that have been reported for other external sandhi processes (most notably /t,d/-deletion, as discussed in Section 2.2), which could form a fruitful avenue of further research.

5.2. Motivations of innovation

While the quantitative analysis discussed in this paper has made it possible to determine the mechanisms of this innovation, the motivations behind pre-pausal [ɡ]-presence have thus far been neglected.

This relatively recent pre-pausal innovation could have been triggered by language-internal factors, specifically by the very nature of how synchronic ‘following segment effects’ are stored and processed in speakers’ grammars. As discussed in Section 2.2, the effect of following consonants in promoting /t,d/-deletion, and of following vowels in inhibiting it, has been analyzed under the Obligatory Contour Principle (Guy, 1980); the same framework can apply here with (ng) variation. Under this analysis, the effect stems from the avoidance of similar adjacent segments, with following consonants sharing more features with the post-nasal [ɡ] than following vowels. This also accounts for the intermediate effect of following liquids on /t,d/-deletion, which share more features with the preceding /t,d/ than a following vowel but fewer than a following consonant. Crucially, pauses by their very nature do not fit into this typology and could therefore be left open to interpretation with respect to their effect on probabilistic external sandhi processes such as these. The possible consequences of this ‘instability’ could be registered synchronically through inter-dialectal differences (e.g., how the behaviour of pre-pausal /t,d/-deletion differs between speech communities), but also diachronically, as reported here for (ng) in Section 4.1, with changes in pre-pausal behaviour over successive generations of speakers.

We can also turn to an entirely different process, of voiceless stop ejectivization, in search for possible explanations. Ejectivization of the English voiceless plosive set /p, t, k/ has been attested by many scholars (Fabricius, 2000; Gordeeva & Scobbie, 2013; Ogden, 2009) and has been said to be increasing over time for /k/, for which it is most frequent (O. McCarthy & Stuart-Smith, 2013). In the same paper, O. McCarthy and Stuart-Smith explore the factors conditioning /k/-ejectivization in speakers of Glasgow English, and find that it is favoured not only phrase-finally but also when preceded by a nasal consonant. That is, the words most susceptible to ejectivization are sink, rank, hunk etc.; these phrase-final /ŋk/ clusters that are frequently ejectivized are essentially the voiceless counterparts to the (ng) clusters that so frequently exhibit post-nasal stop presence in phrase-final position, e.g., sing, rang, hung. These conditioning factors would need to be independently attested in the North West of England, but assuming ejectivization shows comparable behaviour for the speakers recorded here, these two processes could conceivably be seen as part of the same wider phenomenon: a boundary-marking ‘velar fortition rule,’ with parallel changes involved in strengthening voiceless velar nasal + stop clusters through ejectivization and voiced velar nasal + stop clusters through presence of [ɡ].

This innovation could also be driven by external factors; that is, it could be socially-motivated. Utterance/phrase-final position is highly salient,⁶ and as such we may expect the influence of social evaluation to be registered most strongly in this environment. This explanation presupposes two things, however: that (ng) variation is sufficiently above the level of awareness such that it is subject to social evaluation, and if so, that the presence of [ɡ] carries local prestige in these north western communities. If this is indeed the case, perhaps this diachronic change in production, with increasing rates of [ɡ]-presence in highly salient pre-pausal and phrase-final environments, actually reflects a perceptual shift within these communities. Younger speakers may well be attaching local prestige to this post-nasal [ɡ], and actively using this vernacular feature to project a northern identity and align themselves with this dialect region (similar to the use of centralized diphthongs by Martha’s Vineyard residents in Labov, 1963, or the realization of GOAT vowels as [ɵː] by speakers of Tyneside English, in Watt, 2002). The results from Newbrook’s 1999 perception task, discussed briefly in Section 2.1, potentially reflect such a change in evaluation. However, a more recent matched-guise experiment reveals the absence of a community-wide norm with respect to the evaluation of [ɡ]-presence, suggesting that this is not a case of evaluation-driven change (Bailey, to appear).