Regional Distribution of the /el/-/æl/ Merger in A ustralian E nglish (2025)

Abstract: Prelateral merger of /e/ and /æ/ is a salient acoustic feature of speech from Melbourne and the state of Victoria in Australia, but little is known about its presence in other parts of the country. In this study, automated methods of data collection, forced alignment, and formant extraction are used to analyze the regional distribution of the vowel merger within all of Australia, in 4.3 million vowel tokens from naturalistic speech in 252 locations. The extent of the merger is quantified using the difference in Bhattacharyya’s distance scores based on phonetic context, and the regional distribution is assessed using spatial autocorrelation. The principal findings are that the merger is most prominent in Victoria and least prominent in Sydney and New South Wales. We also find preliminary indications that it may be present in other parts of the country.

## introduction the past 20 years have seen an increased interest in the analysis of regional phonetic variation in australian english. prelateral merger of /e/ and /ae/ (where words like celery and salary are both pronounced with @xcite in the first syllable) is a salient feature of the speech of southern victoria (vic), particularly in the city of melbourne, and has been researched in a number of studies (see e.g. @xcite , including some more recent work on perception of the merger @xcite . in locations where it does occur, it is reported to be completely entrenched for some speakers, but still in progress or almost absent for others @xcite . this vowel merger is important because (1) it is one of the few documented features that appears to distinguish the accent of (southern) victorians from the accent of speakers from other states; and in recent years, the rise of automated methods of acoustic analysis and the availability of vast amounts of naturalistic speech data have opened up new opportunities for (socio-)phonetic research. automated formant analysis of naturalistic speech (e.g., @xcite @xcite has been made possible by tools for vowel and formant extraction (e.g., @xcite , which are increasingly incorporated into data extraction and processing pipelines (e.g., @xcite , allowing researchers to work with large samples of real-world, "ecologically valid" speech. although word list data offers a valuable point of comparison, formant values derived from these contexts may not fully align with those obtained from more natural speech, which, although it exhibits variability due to phonological, lexical, and syntactic influences, as well as various situational and social factors, is generally more representative of everyday communication than is data collected in controlled settings @xcite , in addition to providing results that can be more statistically robust and generalizable. this paper demonstrates the feasibility of working with a recent large naturalistic speech dataset from australia @xcite to investigate prelateral merger of /e/ and /ae/. in addition, the study provides an overview of the phenomenon as it occurs across the whole country, providing further evidence for regional phonetic variation for australian english, a variety that although long considered regionally homogeneous, has "begun to exhibit more widespread social and regional variation than has previously been acknowledged" @xcite . ## previous work realization of /el/ as @xcite in melbourne/victoria was first observed at the end of the 1980s (see, e.g., @xcite , yet phonetic research was not carried out until @xcite recorded teenage girls in three towns in new south wales (nsw) and in wangaratta, vic. that study found that /e/ before /l/ was lowered and retracted among the vic as compared to the nsw speakers, and effectively realized as @xcite . however, no such phenomenon was observed among either of the groups when /e/ occurred before the consonant /d/: in those cases, it was pronounced as /e/, suggesting that the merger was exclusively in prelateral contexts. since then, studies into production and perception have shown a high degree of variability in speakerlistener behavior, with research showing a complete merger of /el/-/ael/ for certain speakers in melbourne/vic, while others exhibit a broader range of phonetic behavior. for example, the merger seems to be more common for middle-aged and older speakers @xcite , but this is also dependent on the community @xcite . additionally, older speakers might "hypocorrect" and produce /ael/ as [el] @xcite . in a previous study of variable merger behavior, @xcite analyzed the speech of 12 melbourne speakers in their thirties reading words containing the short front vowels /i, e, ae/. prelateral merger behavior of /e/ and /ae/ was found for 9 speakers, but there were individual differences in both their acoustics and their articulation, which was also measured via ultrasound tongue imaging. @xcite extended the dataset from @xcite to compare wordlist and naturalistic speech, and again found individual variation, where some speakers had the merger only in the wordlist, but not in their naturalistic speech, whereas for other speakers, it was only in their naturalistic speech and not in their wordlist. @xcite examined 628 reading list tokens from 13 older speakers aged 51-80 from ocean grove, vic. they found no merger of /e/ and /ae/ before the /d/ consonant, but significant merger in prelateral pairs such as palate and pellet. in one of the few studies outside of vic, and the only known study in queensland (qld), @xcite found evidence for the merger for some speakers in a study of word list recordings of 17 speakers from northern qld. perception studies (investigating whether people hear the /el/ and /ael/ as the same or different) have shown further support for the merger in melbourne/victoria, especially in the state's southernmost locations, and with lexical frequency playing a small but crucial role in some of the differences between older and younger listeners. for example, younger listeners are biased toward hearing the first name mel when presented with a choice between mel and mal because of an increase in popularity (and thus frequency) of the name mel over time @xcite . based on the prior research, which has primarily centered on vic speakers and word list data, we propose two research questions which guide our paper: ## results overall, the bhattacharyya difference at the 252 locations had a mean value of 0.258, with a standard deviation of 0.132; the range of values was -0.469 to 0.529. the distribution of values is depicted in fig. 1 . difference is highest for vic, followed by wa, the act, qld, tas, sa, nsw, and the nt (fig. 2 ). victorian speakers tend to have substantially lowered (more [ae]-like) vowels for /e/ in prelateral position. fig. 3 shows a subset of the data: eight of the most frequent words of 5 characters or fewer, with the targeted prelateral and non-prelateral contexts, in the nsw and vic subcorpora. for each word, the location corresponds to the nearey-transformed and z-scaled mean formant values for the targeted phone, and the subscript indicates the number of extracted tokens of that word. as can be seen, for prelateral contexts (on the left-hand side), vic speakers have substantially lower /e/ values than do nsw speakers in the words dealt, held, sell, else, tell, help, and well. for value, on the other hand, /ae/ is much lower for nsw-located tokens, suggesting that it remains distinct from /e/ in prelateral contexts for these speakers. for non-prelateral contexts (on the right-hand side), mean nearey-z values for frequent words are quite close for vic and nsw tokens, and no clear regional tendency prevails. to investigate the possibility that the merger is affected by word frequency, we correlated frequency with f1, with f2, and with the euclidean f1/f2 distance. this was done for the 9,838 word types in the dataset (4,297,259 word tokens) as well as for all combinations of vowel and context. no correlations resulted in an @xmath0.07| or a significant p-value. ## discussion spatial distribution of bhattacharyya difference values provides preliminary confirmation that the /el/-/ael/ merger is primarily a victorian phenomenon, and particularly in southern victoria. the regional pattern is evident in the mapped raw values (fig. 4 ), and becomes clearer when the difference value for each location is converted to a g * i statistic (fig. 5 ). raw difference values in the 252 sampled locations are heterogeneous: although the highest values are found in melbourne, and the merger is evident to a lesser degree in other parts of vic, consistent with previous research @xcite , some high values can also be found in, for example, wa, qld, and tas. the lowest values are found in nsw and sa, and locations with low values can be found throughout australia. this heterogeneity likely reflects variability at several levels: firstly, in terms of the sample size and demographic characteristics of the recorded tokens at each location, secondly, in terms of the audio quality for the recordings, which vary between channels and also among the different videos uploaded by a single channel, and finally, in terms of the presence or absence of the merger for individual speakers. this last point aligns with research findings in fine-grained phonetic studies and perception studies, as noted in the introduction. despite the inherent variability in the data, the large sample size tends to reduce the impact of this variability on the analysis. according to the central limit theorem, the sample mean approaches the population mean as sample size increases, leading to more reliable aggregate characteristics. as a result, a geographical pattern emerges more clearly in the difference value map in fig. 4 , and especially in the spatial autocorrelation map in fig. 5 , even if some of underlying data points contain errors (see section 5.1, below). one unexpected finding is that the wa localities sampled in the corpus exhibit relatively high bhattacharyya difference values (and thus also high g * i values), in some cases almost as high as those in the greater melbourne area. although it is possible that the merger is present among some wa speakers, it has not previously been noted in the literature (or remarked upon as a salient feature of perth speech), as far as we know. docherty et al. (2018, fig. 4 ) note that the distance between mean values for the /e/ and /ae/ vowels in conversational speech from perth is smaller than when read aloud, which is typical for english varieties, but they do not mention presence of /el/-[ael]. while our results for wa may reflect the presence of melburnians who have relocated to perth, given the large number of sampled videos in 28 different wa locations, this possibility seems unlikely for all individuals. further investigation of these wa data are also warranted, and will form the basis of a future study. the prospect that the vowel merger may be mediated by word frequency, an idea which has been proposed in several studies of historical vowel shifts @xcite @xcite , is not corroborated in this data. while we find no evidence for broad-based frequency effects, a more fine-grained analysis of particular locations or lexical items may reveal frequency associations. ## summary and future outlook this study has considered prelateral merger of /e/ and /ae/ in a large dataset of geolocated naturalistic speech. we used bhattacharrya diference, a measure of overlap for multidimensional distributions, to characterize the f1 and f2 values for the two vowels in prelateral and non-prelateral contexts. we find that the merger is most evident in southern vic and melbourne, largely confirming previous findings based mostly on word-and reading-list data, but it can also be identified in other state/territory locations, including wa. while this study demonstrates the feasibility of using large, naturalistic speech datasets for phonetic analysis, the results are to be interpreted with caution due to the inherent heterogeneity of the underlying data. several possibilities for further investigation of the merger using this data present themselves, including 1) semi-automatic (or manual) annotation of a curated subset of the data in order to investigate the interaction of the merger with demographic parameters; 2) a focus on particular phonological contexts and/or lexical items; 3) a focus on particular discourse content (for example, is the merger more evident when topics pertaining to melbourne are under discussion in the council meetings that comprise the majority of the underlying data?); and 4) a focus on specific locations or regions which exhibit variability in this data but which have not previously been considered as exhibiting the merger, most notably perth, but also tas, as well as qld, where the merger has already been remarked upon in previous studies. in addition, future work could also explore regional differentiation in other vowel contrasts. one example is the prenasal raising of /ae/ (where words like hand sound like [he:nd]), which is known to vary along various sociophonetic dimensions such as gender, level of linguistic diversity in the community and age @xcite , but has not yet been investigated from the perspective of regional variation. finally, we propose that continued work with this data may help to bridge the "sociophonetic gap" by integrating small-scale analysis of carefully collected word-list tokens with large-scale studies of naturalistic speech. as pointed out by @xcite , "the deployment of socially marked phonetic features in speech performance is [...] considered to be fundamentally driven by an individual's construction and expression of identity". naturalistic speech datasets, such as the one used in this study, could potentially contribute to our understanding of how complex configurations of situational contexts and sociostylistic factors shape particular phonetic realizations -provided they have been carefully filtered and annotated for discourse contexts and personal identity parameters. future work along these lines, we hope, will be able not only to shed light on the /el/-/ael/ merger in australia more generally, but also to explore whether this merger may be moving from being below the level of consciousness in melbourne/vic @xcite to a potential indexical marker of melbourne/vic identity.