Formant frequencies of vowels in 13 accents of the British Isles

34 Pages·2010·1.1 MB·English

Formant frequencies of vowels in 13 accents of
the British Isles
EmmanuelFerragne
&Franc¸oisPellegrino
LaboratoireDynamiqueduLangage,
UMR5596CNRS,Universite´Lyon2
[email protected]
[email protected]
Thisstudyisaformant-basedinvestigationofthevowelsofmalespeakersin13accentsof
theBritishIsles.ItprovidesF1/F2graphs(obtainedwithasemi-automaticmethod)which
could be used as starting points for more thorough analyses. The article focuses on both
phonetic realization and systemic phenomena, and it also provides detailed information
onautomaticformantmeasurements.Theaimistoobtainanup-to-datepictureofwithin-
andbetween-accentvowelvariationintheBritishIsles.F1/F2graphsplotz-scoredBark-
transformed formant frequencies, and values in Hertz are also provided. Along with the
findings,anumberofmethodologicalissuesareaddressed.
1 Introduction
In the linguistic literature, so much attention has already been paid to the phonetics and
phonologyofthemodernaccentsoftheBritishIslesthatonemaywonderwhymoreresearch
isneededinthisfield.Partoftheanswerliesintheconstantlyevolvingnatureofphonological
systemsandphoneticrealizations:whatusedtobetruewhenJohnWellswrotehisAccents
of English some 25 yearsago (Wells 1982) may not entirely apply to currentpronunciation
trends.Recentbooks(Foulkes&Docherty1999,Schneideretal.2004)haveendeavouredto
updateourknowledgeofaccentvariation,oftenfocusingonurbanaccents,intheBritishIsles
(andbeyond),andawholehostofarticleshavebeenpublished.However,asfarasweknow,
norecentpublicationhasprovidedacousticdataforvowelsonalargenumberofaccentswith
thesamemethodology.
Thus, here, we set out to investigate the vowel systems of 13 accents of the British
Isles through acoustic measurements. For the sake of brevity, we will not delve into every
phonetic phenomenon (a more detailed analysis is available in Ferragne 2008); however,
enough information will be given in order to provide as accurate as possible an overview
of present-day acoustic variation. This, we hope, might prove useful as a basis for further
researchoneachaccent(someoftheaccentsbeing,asfarasweknow,notwidelymentioned
intheacousticphoneticliterature,e.g.ScottishHighlands),andcouldalsobecomparedboth
with other contemporary acoustic descriptions of vowel systems and earlier descriptions,
the latter potentially leading to a better understanding of phonetic changes. We believe that
such an endeavour could be useful for linguists and phoneticians looking for a compact
JournaloftheInternationalPhoneticAssociation(2010)40/1 (cid:2)C InternationalPhoneticAssociation
doi:10.1017/S0025100309990247
2 EmmanuelFerragne&Franc¸oisPellegrino
Table1 AccentsoftheABIcorpusandnumberofsubjectsandvowels.
Subjectsin Subjectsin
monophthong diphthong Numberof
Abbreviation Accent Place analysis analysis voweltokens
brm Birmingham Birmingham 7 6 517
crn Cornwall Truro 2 2 161
ean EastAnglia Lowestoft 7 5 473
eyk EastYorkshire Hull 8 6 588
gla Glasgow Glasgow 7 7 523
ilo InnerLondon London notincluded(seesection2.2)
lan Lancashire Burnley 10 9 763
lvp Liverpool Liverpool 8 5 561
ncl Newcastle Newcastle 2 2 147
nwa NorthWales Denbigh 7 7 544
roi RepublicofIreland Dublin 7 6 528
shl ScottishHighlands Elgin 11 11 865
sse StandardSouthernEnglish London 6 6 472
uls Ulster Belfast 6 5 482
Total 88 77 6624
overview of geographically-induced phonetic and phonological variation in the British
Isles. The article can also serve as a basis for more sophisticated pronunciation modelling
for speech technology purposes (speaker indexing, automatic accent classification – see
Ferragne&Pellegrino2007).
2 Material and method
2.1 Corpus
TheAccentsoftheBritishIsles(ABI;D’Arcyetal.2004)corpusincludesrecordingsfrom
14 areas covering the British Isles. On average, 20 subjects (equally divided into men and
women) took part for each region. The speakers had lived all of their lives in the region
in question, and their parents had lived there, too. The target age range was from 18 to
50yearsoldbut,insomeareas,theactualrangeis16–79.Therecordingstookplaceatthe
beginningof2003.Table1showstheabbreviationsthatwillbeusedthroughouttodesignate
theaccents,themeaningoftheseabbreviations,wheretherecordingstookplace,thenumber
of subjects whose vowels will be actually graphed, and the number of vowel tokens per
accent.Thenumberofsubjectsissplitintotwocolumns:theleftmostcolumncontains, for
each accent, the number of subjects whose data contribute to monophthong plots, and the
numberofsubjectsusedinthediphthongplotsappearsintheothercolumn.Thefiguresinthe
columnsdifferasaresultofthescreeningprocedure(seesection2.2).Itisworthmentioning
that no information on the participants is available, which de facto precludes the study of
phonetic variation caused by sociological (in a broad sense) factors. In particular, it would
have been desirable to know the age of the participants because many studies (e.g. Labov
1994,Foulkes&Docherty1999,Hawkins&Midgley2005)haveshownthataspeaker’sage
isacentralfactorinexplainingphoneticandphonologicalvariation.Nevertheless,although
theseimportantfactorscannotbecontrolledforaposteriori,standardspeakernormalization
techniqueswillbeappliedtothedata(seesection2.2).
VowelsinBritishIslesaccents 3
Table2 Test-words, (assumed) corresponding lexical sets,
andconventionalvowelcategory.
Test-word Lexicalset Conventionallabel
heed FLEECE monophthong
hid KIT monophthong
head DRESS monophthong
had TRAP monophthong
hard START monophthong
hod LOT monophthong
hoard FORCE monophthong
hood FOOT monophthong
who’d GOOSE monophthong
Hudd STRUT monophthong
heard NURSE monophthong
hade FACE diphthong
hide PRICE diphthong
hoid CHOICE diphthong
hoed GOAT diphthong
howd MOUTH diphthong
hared SQUARE diphthong
heered NEAR diphthong
hured CURE diphthong
The speech material we are concerned with here is a list of 19 /hVd/ words that the
subjectswereaskedtoreadfivetimes:heed,hid,head,had,hard,hod,hoard,hood,who’d,
Hudd,heard,hade,hide,hoid,hoed,howd,hared,heered,hured.Theuseofsuchstimuliis
meant to factor out both the effects of coarticulation and the acoustic variation determined
by information-related phenomena such as linguistic redundancy (Wright 2003, Aylett &
Turk 2006). One obvious drawback of this approach lies in the questionable suitability of
non-words or rare words (we return to this point, and other disadvantages, below, in the
Discussion section). However, D’Arcy and colleagues, who recorded the data, provided the
subjectswithcommonwordsthatthe‘difficult’/hVd/targetsweresupposedtorhymewith.For
instance,thesubjectswereinstructedthathoidwastorhymewith(cid:3)void(cid:4),hoed,with(cid:3)showed(cid:4),
howd,with(cid:3)loud(cid:4),etc.(D’Arcyetal.2004:116).Intheremainderofthepresentarticle,both
test-wordsandstandardlexicalsets(Wells1982)willbeused,ofteninterchangeably.Forthe
correspondence to be explicit from the start, test-words and standard lexical sets have been
matchedintable2;thismakescomparisonswithotheraccentstudieseasier.Thetableshows
whichlexicalsetofStandardSouthernBritishEnglishis–sotheauthorsthink–exemplified
by each test-word; but it does not go so far as to imply that all speakers phonologically
interpretedeachtest-wordasamemberofthelexicalsetitisassociatedwithinthetable(see
the Discussion for a more thorough treatment of the bias induced by reasoning in terms of
the lexical sets of Standard Southern British English). For the sake of legibility, the vowels
were split between monophthongs, closing diphthongs, and centring diphthongs, following
thephonologicallabelstheyaregiveninclassicdescriptionsofReceivedPronunciation(RP;
Jones2003,Wells2008).Ofcourse,thisconventionaldivisiondoesnottellusanythingabout
theactualphoneticrealizationofavowelinagivenaccent.Theconventionallabelsforvowels
arelistedintable2.
In this paper, we only report male data on the grounds that gender is known to be an
important factor of phonetic variation; thus, including data from two genders would have
necessitated separate graphs and comments, which would have considerably increased the
4 EmmanuelFerragne&Franc¸oisPellegrino
lengthofthispaper.Thechoiceofmaleratherthanfemaledatawasdeterminedbythefact
thattypicalityscores(seebelow)wereonlyavailableforthemaleparticipants.
2.2 Method
Giventhelackofinformationonindividualsubjects,aphonetician,nativespeakerofEnglish,
wasaskedtolistentoallspeechsamplesrecordedbythe145malespeakersandtocomeup
withscores(onafive-pointscale)reflectingthetypicalityofthespeaker’saccentaswellas
intra-accenthomogeneity.Theexpertphoneticianwastoldtolistentothefirstpartoftheread
passage(theABIcorpuscontainsareadpassageofabout300words)andcouldstopplaying
asoundassoonashehadformedanopinionastothetypicalityofthesampleunderscrutiny.
Thisassessmentledustoleaveoutthesamplelabellediloonaccountofsubstantialwithin-
samplephoneticvariability(mainlybroughtaboutbydifferencesinethnicbackgrounds).A
more thorough assessment with more listeners and some measure of listeners’ agreement
constitutesapotentialfollow-upstudy.
Formantshavelongbeenheldtobewell-suitedparametersfordescribingvowelquality,
mainlybecausetheF1/F2planecorrelateswithtraditionalarticulatory–auditorytrapezoidal
representationsofvowels.However,DeWetetal.(2004)emphasizethat,todate,noautomatic
tool can reliably extract formants. As a consequence, the reproducibility of measurements
is not guaranteed and the processing of very large speech corpora may prove a very time-
consumingtask.Weoptedforacompromisethatwouldminimizehumaninterventionwhile
preservingthebenefitsoftheF1/F2representation.
Theremainderofthissectionexplainshowformantmeasurementswerecalculated.The
methodologyincludestherejection,aftervisualassessment,ofvoweltokenswithanobvious
mismatch between spectrogram and estimated formant tracks, the automatic determination
ofvowelboundariesbasedonF0detection,theconversionofHertzvaluestotheBarkscale,
thesmoothingofformantcontourswithregressiontechniquesinordertoruleoutremaining
formanttrackingerrors,andthecomputingofLobanov-transformedvalues(seebelow).
Abroad-bandspectrogramwithsuperimposedformanttrackingwasobtainedwithPraat
(Boersma & Weenink 2008) – and the Burg algorithm set to default parameters – for each
of the 26,408 vowels. Each such representation was visually inspected: when a complete
mismatch was observed between formant tracking and spectrogram, the vowel in question
was rejected; otherwise – and even if there was a slight mismatch – the vowel was kept for
furtheranalysis.Thescreeningprocedureleftuswith22,331vowels.
The ABI corpus comes complete with word-level segmentation, so that the boundaries
of each /hVd/ word are clearly identified. In order to extract the vocalic nuclei, automatic
F0 detection was run using the Snack Sound Toolkit (Sjo¨lander 2004) and the voiced part
was kept. It should be borne in mind here that in such test-words as hard, heard, etc., a /r/
followsthevowelsinrhoticaccents(crn,gla,lan,roi,shl,uls).Inthoseaccentswhere/r/is
realizedasanapproximant,F0detectiondidnotallowforseparationbetweenthevoweland
the/r/(besides,somevowelswerer-colouredthroughout),whichledus–forwantofabetter
method–tokeepthewholespeechportion.Asaconsequence,wehaveincludedcomments
onrhoticityandthephoneticrealizationof/r/whererelevant.
Priortoacousticmeasurements,formantvalueswerere-sampledusinglinearinterpolation
inorderforeachvoweltohavethesamenumberofvalues,namely13,whateveritsduration.
This was done for the sake of convenience: for instance, for numerical techniques such
as regression, numbers were more easily handled when stored in vectors of constant size.
However,itmustbenotedthatthedurationratiobetweenformantsteadystatesandformant
transitionsvariesacrossvowelsandspeechrates(Gay1968,1978),soourmethodcausesa
slightlossofinformation.
Beyond our conventional split of the vowels into monophthongs and diphthongs, we
still had to decide if a vowel would be represented, in terms of phonetic realization, as one
or the other type. After listening to each vowel token and visualizing the corresponding
VowelsinBritishIslesaccents 5
Figure1 F2fromthevowelofhadebyspeakerPDKfromlan:originalformanttrack(circles),classicregressionline(solidline),
androbustregressionline(dashedline).
spectrogram, it was decided that all the vowels that had been labelled as monophthongs a
prioriwouldbetreatedassuch.Althoughsomeofthemareslightlydiphthongizedinsome
accents (see e.g. ean below), the rule was applied systematically. Similarly, all the vowel
tokensconventionallycalleddiphthongswerevisuallyandauditorilyinspected,and,ineach
accent,thepatternfoundmostoften(which,inpractice,alwaysprovedfarmorefrequentthan
alternativevariants)determinedhowavoweltypewouldbeanalyzedinthisparticularaccent.
Given the small number of alternative variants in each accent, we reckoned that computing
medians and interquartile ranges for all vowel types would guarantee insensitivity to those
variantsandthereforespareusanadditionalsortingofspeakers.
F1 and F2 values were then Bark-transformed (Traunmu¨ller 1990), and robust and
polynomial regression techniques were applied to smooth formant trajectories and rule out
outlying values. The specific kind of regression to be employed was decided for each type
of vowel and depended on the accent. For instance, the vowel of FACE in most accents of
the north of England is a monophthong, so robust linear regression was deemed sufficient
to characterizethe formant. Figure 1 shows the second vocalic formant of hade after linear
interpolation‘re-sampling’(circles)producedbyspeakerPDKfromlanwithregressionlines
obtainedwithclassic–ordinaryleastsquares–regression(solidline)androbust–weighted
least squares – regression (dashed line). The figure makes it clear that the latter technique
(whichweadoptinthepaperformonophthongs)provessuperiorinthat,intuitively,itmatches
themonophthongpatternmoreclosely,whereastheclassicregressionline,mostlybecauseof
thefinalformantvalues,leadstoanoverestimationofstartingvaluesandanunderestimation
ofmostvaluesinthesecondhalfofthevowel.
AsfarasthePRICEvowelisconcerned,acubicpolynomialmodelwasadoptedsothatthe
S-shapedtrajectoriesofF1andF2inmanyaccentswouldbeaccuratelyrendered.Infigure2,
thecirclesrepresentthesecondformantofthehidevowelspokenbyspeakerCTSfromlvp;
thesolidlinewasobtainedthankstocubicpolynomialregression,whichallowsacurvilinear
trajectorywithatmostoneinflectionpoint.
The so-called Lobanov (z-score) transform was applied to each formant separately and
for each speaker independently in order to erase physiologically-induced acoustic variation
(Lobanov 1971, Adank et al. 2004). In practice, for example, all F1 values measured at
temporal mid-point on the regression line in the monophthongs of one single speaker were
z-scored, and the same was applied to F2. Such a normalization procedure implies that a
speakerproducesatleastonetokenofeachvoweltype,whichwasnotalwaysthecase(asa
6 EmmanuelFerragne&Franc¸oisPellegrino
Figure2 F2fromthevowelofhidebyspeakerCTSfromlvp:originalformanttrack(circles)andcubicregressioncurve(solidline).
consequence of the screening procedure described above). Speakers with incomplete vowel
sets were therefore removed for the remainder of the acoustic analysis, hence the variable
numberofremainingspeakers(table1)acrossaccentsandvowelcategory(i.e.monophthongs
vs.diphthongs)andthereductionofvoweltokensfrom22,331to6,624.Incidentally,thelow
number of crn and ncl speakers warns us against being too confident about the acoustic
resultsforthesetwoaccents.However,alongwiththeacousticdata,anauditoryanalysisof
allspeakers–includingthosewhowereremovedduringthescreening–wascarriedoutby
theauthors.
In addition to F1/F2 plots, probability density estimates based on kernel smoothing
(Everitt, Landau & Leese 2001: 16–20) will be presented for some pairs of vowels
necessitating finer-grained comparison (see e.g. figure 16 below). The resulting figures can
be interpreted as smoothed histograms, and they are particularly helpful when it comes to
decidingtowhatextenttwovowelscanbesaidtobelongtoasinglephoneme.
Durationvalueswillonlyoccasionallybereported(e.g.infigure16),whenspectralquality
alonewasnotenoughtodetermineiftwovowelswereidentical.But,althoughdurationplays
a crucial role in the phonological system of many accents, we chose not to include this
parametersystematically.Thereasonisthat,toamuchlargerextentthanformants,duration
is influenced by the specific type of speech material analyzed here. In other words, the fact
thatmonosyllabicwordsappearedinalistresultedinhugeinter-individualvariationand,on
average,durationvaluesweremuchhigherthanonewouldexpectinnaturalspeech.
TheresultingF1/F2plotsarepresentedbelowforeachaccent.Sseappearsfirst,andthen
allremainingaccentsarepresentedinalphabeticalorder.Giventhatonlytwospeakerscould
beanalyzedacousticallyincrnandncl,itwasdecidedthatoneplotforeachspeakerwould
be provided in these accents. The z-scored Bark-transformed F1/F2 values plotted for the
monophthongsweremeasuredatthetemporalmidpoint.Onaccountoflargewithin-dialect
differences in phonetic realization, the median and the interquartile ranges were used as
estimatorsofcentraltendencyandspread,respectively,ratherthanthearithmeticmeanand
thestandarddeviation. Fortheclosing diphthongs, thearrowsrepresenttheinitialandfinal
(arrowhead)medianF1andF2valueswitherrorbarsspanningtheinterquartilerange.The
actualmeasurementsweremadeat2/13and11/13ofthedurationofthevowelinanattemptto
minimizetheimpactofcoarticulation.CentringdiphthongsarenotplottedintheF1/F2plane,
mainly because of their within-dialect variability and especially due to the inconsistencies
elicited by the ill-suited test-word hured (see Discussion). Nevertheless, some of them will
beillustratedwithspectrograms.
VowelsinBritishIslesaccents 7
Figure3 Medianandinterquartilerangeforthe11monophthongsproducedbysixmalespeakersofsse.
A complete description of each and every vowel for all 13 accents would indeed be
extremelytedious.Instead,wewillfocusonarestrictedset–varyingfromonedialecttothe
next–ofthemostnotablephenomena.
3 Results
3.1 StandardSouthernEnglish(sse)
The accent sse serves as a reference against which the remaining accents are compared. It
has been described in detail in many publications (Nolan 1998, Jones 2003, Upton 2004,
Hawkins & Midgley 2005, Wells 2008, etc.). As figure 3 shows, the vowels of who’d and
hood (which are supposed to instantiate the GOOSE and FOOT sets, respectively) are more
frontthanrecentpronunciationdictionariessuggest(Jones2003,Wells2008).Thisfindingis
howeverinaccordancewithup-to-dateacoustic–phoneticdescriptions(Hawkins&Midgley
2005,McDougall&Nolan2007).
Asfarasclosingdiphthongsareconcerned,figure4showsthatthevowelofPRICEhasa
ratherbackstartingelementwhilethatofMOUTHisratherfront,thedifferencebeingaudibly
perceptible. In earlier descriptions, O’Connor (1973) and Gimson (1980) used the symbols
/a/ and /ɑ/ for the starting element of PRICE and MOUTH, respectively. Nowadays, although
Jones(2003)andWells(2008)useasinglesymbolforthefirstvowelofPRICEandMOUTH,
thevowelplotsprovidedinthesedictionaries(Jones2003:viii;Wells2008:xxiii)explicitly
show that the authors keep considering that the first element in MOUTH is slightly more
back than that of PRICE. In contrast to the latter, other recent publications have symbols for
PRICE and MOUTH that are much more in line with our findings. Upton (2004) records two
variants for PRICE: [ai] in traditional RP and [Øi] in contemporary RP. He, however, notes
justonepossibilityforMOUTH:[aυ].Olausson&Sangster(2006)alsouse[Øi](PRICE)and
[aυ] (MOUTH). In a review of vowel symbols in dictionaries, Windsor Lewis (2003: 147)
comments on the use of [Øi] instead of [ai]: according to the author, ‘[t]he apparent Upton
suggestionthat/ai/and/aυ/havenowreversedtheirrelativestartingpositionsinmainstream
usage is not supported by my observations and I know of no-one else of such an opinion’.
WindsorLewisgoessofarastoclaimthatthesymbols[ai]and[ɑυ](forPRICEandMOUTH)
8 EmmanuelFerragne&Franc¸oisPellegrino
Figure4 Medianstartingandendpointforthe5closingdiphthongsproducedbysixmalespeakersofsse.
would still be totally defensible. In others words, he seems to reject any possible phonetic
developmentinthepronunciationofthesetwovowels.Healsoremindsthereaderthatwhen
Gimson(inthefourteentheditionoftheEnglishpronouncingdictionary,in1977)departed
fromearlierversionsofJones’sdictionarybydropping[ɑυ]infavourof[aυ],itwasforthe
sakeofsimplicity,anditcertainlydidnotreflectanyphoneticchange.
Now,focusingonthequestionofapotentialreversalbetweenthestartingpointsofPRICE
andMOUTH(andnotontheprecisephoneticqualityoftheformer),ouranalyses,bothacoustic
andauditory,suggestthatthespeakersinoursampledohavesuchareversal.Whetheritis
theresultofanevolutionaryprocessisstilldebatableandwouldneedmorethoroughresearch
(e.g.withagreatersample),butotherfactorscomeintoplayinthiscontroversy.Firstly,the
answer can be influenced by how conservative the definition of the accent is. For instance,
Upton(2004:219)aimsatdescribinga‘kindofmodern,“diluted”ReceivedPronunciation’,
Jones (2003: v) describes the pronunciation of BBC newsreaders, and Wells (2008: xix)
provides transcriptions that ‘cover very much more than a narrowly defined RP’. As far as
ourssesampleisconcerned,theassessmentbyaBritishphonetician(seesection2.2)yielded
typicalityandhomogeneityscoresof3/5;whichsuggeststhatourdefinitionofsse(whichwe
equatewithwhatotherslabelRP)isindeedquitelax.
Secondly, most of the references (especially dictionaries) quoted here target learners of
English as a second language and non-specialist native speakers. As a consequence, the
transcriptionsreflectacompromisebetweenphoneticaccuracyandsimplicity.Insuchbooks,
distinguishingonlybetween[ai]and[aυ]makesperfectsenseintermsofparsimony;besides,
symbolsaremereconventions.Sothisisanotherreasonwhywewillguardagainstinferring
potentialphoneticchangesfromsymbolsusedinbroadtranscriptions.
So,fromourssesample,wehavenomeansofknowingwhethertheratherbackposition
ofthefirstelementofPRICE(relativetothatofMOUTH)istheresultofahistorical process,
and we cannot tell to what extent our sample matches the population whose pronunciation
is described in dictionaries. Wells (1982: 310) recorded this phenomenon (which he calls
PRICE–MOUTHCrossover)inthePopularLondonaccent;giventhatoursubjectshaveallbeen
recordedinLondon,itmaywellbethattheirtypeofStandardEnglishisinfluencedbylocal
featuressuchasthePRICE–MOUTHCrossover.
Inoursample,thevowelofharedismostoftenamonophthong(figure5),andmorerarely
amonophthongfollowedbyashortoffglidetowardsthecentreoftheF1/F2space.Thisagain
supports the transcription used by Upton (2004) and Olausson & Sangster (2006) (i.e. [ε…])
VowelsinBritishIslesaccents 9
Figure5 SpectrogramofharedproducedbythespeakerDMEfromsse.
Figure6 SpectrogramofheeredproducedbythespeakerHAKfromsse.
and somewhat contradicts Jones 2003 and Wells 2008, who suggest that the SQUARE vowel
isacentringdiphthong(Upton2004:226claimsthatthediphthongcharacterizestraditional
RP).
Unlike the SQUARE vowel, the most frequent variant for the heered vowel is a centring
diphthong(figure6);butmonophthongsarenotuncommon.Thediphthongalnotationcanbe
found unanimously in Jones (2003), Upton (2004), Olausson & Sangster (2006) and Wells
(2008).
The test-word hured was quite problematic: it very frequently yielded, within the same
accent,between-andalsowithin-speakervariation.Giventheapparentlackofagreementas
tohowthespeakersphonologicallyinterpretedthisword,wedecidedtoexcludeitfromthe
restofouranalysis.
3.2 Birmingham(brm)
The accent of Birmingham (brm) is generally thought to pattern with the northern English
accents,partlybecauseneithertheFOOT–STRUTsplitnortheTRAP–BATHsplitissaidtohave
occurredintypicalbrm(Clark2004).But,accordingtoWells(1982:354),‘manyeducated
northerners ... wouldnotbecaughtdeaddoingsomethingsovulgarastopronounceSTRUT
words with [υ]’; thus, sociolinguistic variation must be expected. This suggests that, since
sociolinguisticfactorshavenotbeencontrolledinthecorpus,theaverageformantvaluesfor
FOOTandSTRUTmaybemisleadinginthattheypotentiallyreflectthepronunciationofboth
speakerswithandspeakerswithouttheFOOT–STRUTsplit.
10 EmmanuelFerragne&Franc¸oisPellegrino
Figure7 Medianandinterquartilerangeforthe11monophthongsproducedbysixmalespeakersofbrm.
Figure 7 displays the monophthongs of the male speakers of brm. Given that the
distributions of hood and Hudd only slightly overlap, it can be thought that the majority
of speakers likely have two phonemes here. An auditory analysis actually reveals that only
half of the 20 (male and female) speakers from the brm sample have a perfect homophony
betweenhoodandHudd,whichexemplifieswhycomputingaveragesonformantvaluesmay
provemisleading.InsomespeakerswhosesystemhasseparatevowelsforFOOTandSTRUT,
theSTRUTvowelisveryclosetothatofNURSE(heard),totheextentthatdurationseemsto
betheonlyreliablecuetodistinguish them.Relativetosse,whereSTRUThasaratheropen
quality, the brm vowel is closer to the centre of the vowel space. This central quality for
STRUT is typical of educated and mobile northerners, as evidenced in a perceptual study by
Evans & Iverson (2004): when asked to find best exemplars of STRUT words in a carrier
sentence spoken in southern English, northern subjects living in London adjust their
representationwhilenorthernersstilllivinginthenorthdonotnormalizeforaccent.However,
theperceptualadjustmentperformedbymobilenorthernersdoesnotmatchvowelsactually
producedbysoutherners;itonlycomesclosetoaschwa-likequality.
Now, turning to the diphthongs of brm (figure 8), the starting quality of PRICE appears
slightlylessopenthaninsse.Actually,anauditoryinspectionincludingallspeakersreveals
thatitisnoticeablybackandclose.Wehavefoundnoevidencesupportingapotentialmerger
involvingPRICEandCHOICE(thispossibilityismentionedbyWells1982:363–364),although
in some speakers the two vowels are perceptually very close to each other. The test-word
haredhasalongmonophthongforallspeakers;heered,acentringdiphthong.
3.3 Cornwall(crn)
According to Wells (Wells 1982), the accent of Cornwall (crn) clusters with the accents of
the south-west of England, although it has a different linguistic tradition from surrounding
counties. Crn is rhotic, which means that the graphic (cid:3)r(cid:4) in the test-words has a phonetic
equivalent.Theinfluenceofarealized/r/ontheprecedingvowelmanifestsitselfindifferent
ways: for instance, in some realizations of heard, F3 collapses abruptly towards the middle
oftheautomaticallyextractedsignalportion,whichindicatesthatthevowelandthe/r/occur
in succession, while other vowel tokens display astable low F3throughout, suggesting that
thevowelisr-colouredthroughout.
Figure9andfigure10showthemonophthongsproducedbyeachofthetwocrnspeakers.
Auditorily,theGOOSEvowelisparticularlyvariable;backvowels(figure11),comparatively
frontqualities(figure12)anddiphthongizedvariantsareattested.