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Dialect variation and formant frequency: The American Englishvowels revisited

Robert HagiwaraWaisman Center & Department of Communicative Disorders, University of Wisconsin-Madison, Madison,

Wisconsin 53706

Received 9 February 1996; accepted for publication 27 February 1997

Vowel production data collected from 15 southern Californian English-speaking monolinguals is

compared with data reported by Hillenbrand et al. J. Acoust. Soc. Am. 97, 30993111 1995 and

Peterson and Barney J. Acoust. Soc. Am. 24, 175184 1952. Recordings were made of ninewomen and six men producing multiple repetitions of{, (, |, }, ,, , *, , , #, [o in three consonant

contexts. The frequencies of the first three formants were measured by simultaneous comparison of

wideband spectrograms, narrow-band FFT spectral slices, and LPC spectra taken at vowel center, or

steady state where available. The Southern Californian data are seen to differ greatly from that

described by Peterson and Barney 1952 and Hillenbrand et al. 1995. 1997 Acoustical

Society of America. S0001-49669704906-0

PACS numbers: 43.70.Fq, 43.70.Hs AL

Reference to formant frequency data from a wide variety

of American English dialects is useful in forming and testing

theories of vowel features, of the relation between speech

production and perception, and the progress of sociolin-

guistic change, as well as in providing adequate information

for building speech technological applications in recognition

and synthesis, and establishing dialect-appropriate norms in

clinical speech therapy. However, there is a dearth of such

data.

The purpose of this study is to illustrate the variability

observed across American English dialects in the domain of

steady-state formant frequency, and to provide, in the ab-

sence of more extensive data from Southern Californian En-

glish, a verifiable and testable set of formant frequency

norms for adult men and women. Vowel data from college-aged southern Californian speakers will be seen to diverge

from similar data reported for northern Midwesterners Hil-

lenbrand et al., 1995, and from General American speak-

ers Peterson and Barney, 1952. This letter is also an appeal

to other researchers to produce similar, local studies of

American English, with a view to cooperatively producing

an acoustic atlas of American English dialects as indi-

cated by formant frequency.

The data in this study comprise a subset of the data

reported in Hagiwara 1995, which contains a fuller descrip-

tion of the complete corpus than will be included in this

letter. Undergraduate students at UCLA were asked to re-

spond to a Speaker Survey Form if they were willing to

participate in a phonetic study of /./ in dialects of American

English. Of the respondents to the survey, 15 were selected

for their similarity in age 1826, geographic background,

and gross socioeconomic and educational indicators. They

represent a relatively unmarked, middle-class, suburban

population. They include Anglo-Americans, African Ameri-

cans, and Asian Americans, but appear to represent as uni-

fied a speech community as can reasonably be studied with-

out imposing predetermined sociometric boundaries on a

target group of speakers. That is, to the degree that South-

ern California American English is a dialect within which a

certain amount of ethno-social variation is to be expected,

these 15 appear to represent the region. Each was compen-

sated $10 U.S. for participating in the study.

Sixty-nine monosyllabic words were selected to illus-

trate the plain nonrhoticized vowels and three allophones

of /. / in southern California English. Thirty words illustrate

plain vowels in three consonantal environments: /b_t/, /t_k/,

and /h_d/. Three exemplify syllabic /[/ in the same environ-

ments. These 33 words together form the database for the

present study. Table I lists the words used. Only real English

words and familiar proper nouns were used; where a word of

the appropriate phonological shape did not exist, a word as

close in shape as possible to the target was substituted, as

with put. The word hoed was respelled as a propernoun Hode to avoid its relatively odd-looking spelling.

Each word was presented in the frame Cite__twice.

This frame was selected to provide citation form pronun-

ciations, but in a continuous speech stream. The symmetri-

cal, nonflapping coronal environment was necessary for a

simultaneous study conducted with the same speakers. Each

word/frame was included three times in random order in a

single recording script. Each speaker was recorded reading

from the script in a sound-treated room on professional qual-

ity equipment.

The subjects speech was digitized from the audio cas-

sette tape of the recording session at 10 kHz using the Kay

Elemetrics Computerized Speech Laboratory. Frequencies

were measured for the first three formants ( F1 , F2 , F3) of

each syllabic nucleus in the words illustrating syllabic [o

and other vowels. Formant frequencies were determined by

simultaneous evaluation of several transforms of the signal.

These included wideband spectrograms and narrow-band

FFT spectra averaged over a 30-ms window through the

steady-state portion of the vowel, if there was one. If no

steady state was present, the 30-ms window was placed in

the center of the vowel. Bandwidths for spectrograms and

narrow-band spectra were varied to achieve the best formant

655 655J. Acoust. Soc. Am. 102 (1), July 1997 0001-4966/97/102(1)/655/4/$10.00 1997 Acoustical Society of America

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subtly, the / / and /* / vowels in the PB are extremely back

have extremely low F2s. While still low the HGCW F2values for // and /*/ are slightly higher than in PB.

The configuration in Fig. 3 indicates a well-established

Northern Cities Shift, such as described recently by La-

bov 1994, summarizing sources therein. The Northern Cit-

ies Shift dialects are characterized by a centralized reflex of

// more properly /~/, and a raised / , /, among other

changes, that have been observed to varying degrees in the

cities of Detroit, Chicago, and Cleveland, as well as upstate

New York. HGCW described their speakers as being raised

in southern Michigan and other areas in the upper midwest.

Thus it is fair to assume that, even if they are not speakers of

Northern Cities Shift dialects, they are from areas heavily

influenced by them. Thomas 1958 refers to the relative cen-

trality of / / in his Northern Central dialects, which in-

clude the northern midwest, the same region studied in

HGCW.

The PB study, conducted at Bell Laboratories in New

Jersey, used speakers from a variety of places, and even

some who spoke other languages than English natively.

However, the women speakers in that study are identified as

primarily from the Middle Atlantic region. Thomas 1958indicates that the Middle Atlantic region includes most of

New Jersey, and specifically excludes upstate New York and

the northern Midwest.

Comparing Figs. 1 and 3 reveals as many differences

between HGCWs vowel space and the southern Californian

space as between HGCW and PB. This clearly demonstrates

considerable variation between contemporaneous regional

variants of American English.

The purpose of this discussion is merely to demonstrate

that American English is an amorphous entity at best, and

that there are considerable regional and also social differ-

ences, particularly in urban centers Labov, 1994. In discus-

sions of vowel production, references to General Ameri-can are not as informative as references to data from

specific dialects.

Throughout this report, an effort has been made to char-

acterize the southern Californian vowel space and the spaces

reported in HGCW and PB without reference to an arbitrary

standard. In their paper, HGCW point out that the PB results

are often regarded as the definitive set of static formant fre-

quencies describing the American English vowels, serving as

a comparator with other languages and pathological speech,

target values in speech synthesis, prototype values, etc. Such

a view clearly misrepresents the intent of PB, and belies the

reality of the whole of American English, even perhaps

General American. At best, the PB results are a profile ofa specific dialect at a specific time in the history of that

dialect HGCW, p. 3108.

Implicit in HGCWs discussion is the need for more

such profiles. HGCW provide one, with the purpose not only

of replicating the PB study but also determining the how

dynamic information can be used to discriminate vowels.

The data in the present study represent another profile of a

different dialect. They were collected originally with the in-

tention of providing baseline F3 measurements against

which lowered F3 in American /./ could be compared Hagi-

wara, 1995. However, as this paper argues, the resulting

information about the form of the southern Californian

vowel space is interesting in its own right, particularly as it

provides counterpoint to the view of the PB or the HGCW

formant values as somehow representative of the state of

American English as a whole.

As HGCW point out, large studies are consuming of

time, money, and scholarly resources. Documentation of ev-

ery American dialect on such a scale is obviously beyond the

scope of any single researcher or research group, especially

considering that in the best case it would include more than

static formant frequency information. However, studies of a

dozen or so speakers are well within the scope of most re-

searchers, perhaps most students, and, in the absence of stud-

ies of large numbers of speakers, would be better than noth-ing. If the results of many such studies were combined, they

would fill a significant void in objective descriptions of

American English, and help pinpoint areas where the greater

resources of larger, or more expansive studies may most

profitably be employed.

Such investigations would not only lead to a better un-

derstanding of American English vowels, but also yield a

database of general interest to phonetics, sociolinguistics,

speech training, and speech technology.

ACKNOWLEDGMENTS

The author would like to thank Peter Ladefoged, James

Hillenbrand, and two anonymous JASA reviewers for com-

ments on earlier versions of this letter.

Hagiwara, R. 1995. Acoustic realizations of American /./ as produced by

women and men, UCLA Ph.D. dissertation. Also UCLA Working Papers

in Phonetics 90.

Hillenbrand, J., Getty, L. A., Clark, M. J., and Wheeler, K. 1995. Acous-

tic characteristics of American English vowels, J. Acoust. Soc. Am. 97,30993111.

Labov, W. 1994. Principles of Linguistic Change, Volume 1: Internal

Factors Blackwells, Cambridge.

Peterson, G. E., and Barney, H. L. 1952. Control methods used in a studyof the vowels, J. Acoust. Soc. Am. 24, 175184.

Thomas, C. K. 1958. An Introduction to the Phonetics of American

English Ronald, New York, 2nd ed.

658 658J. Acoust. Soc. Am., Vol. 102, No. 1, July 1997 Robert Hagiwara: Letters to the Editor

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