The major pitch features of vocalic quality

Lingua 25 (1970) 142-151, @ North-Holland Publishing Compa*~y N~t to be rcp0vdu¢¢clin a~y form~rithoutwrittenperml~Monfromthe publisher

THE MAJOR

PITCH FEATURES

OF

VOCALIC QUALITY HAROLD

J. P A 1 3 D O C K

SUMMARY Acoustic anMysis and synthesis of Russian palatalization and Arabic 'emphasis' were carried out in order to investigate the J~kobsordau tonality features called sharp anal fiat. The result~ irtdieate that the above ieatures form the extremes of a t,itch-tike auditory dimension which is related to th,: separation bet~seen the two commonly accepted pitches of:vowels - one of which is stimulated by FI, the other by the F 2 + group of ferments. This suggests a purely auditory three-dimensional vowel space which not only provides theoretical justification Jot the use of traditional vowel diagrams bl,t also furnishes discrete perceptual correlates for all three of Jakobson's or~'.l resonance dimensions; t h a t is, sharp-flat, acute-grave, and compact-OMfusc. THRE~- PROPOSED PITCH DIMENSIONS

This paper will attempt to describe some of the insights into vowel quality which were gained in the course of an acotmtic and perceptual investigation of the Jakobsoniaa extreme tonality (i.e., filter or vocalic) features called sharp and flat as manifested by Russian 'softening' (palatalization) and Egyptian colloquial Arabic 'emphasis' (perhaps mostly pharyngealization) respectively. The evidence examined was of two types: (1) acoustic -mostly spectographic; and (2) perceptual - English plus Russian or Egyptian responses to synthesized syllables. The generalization suggested by the initial acoustic analysis was fully supported by the subsequent responses to the synthesis. Both types of evidence indicated that the chief acoustic cue for both Russian sharp and Arabic flat is the degree of separation between F1 and F2-maximal for sharp, minimal for flat. One may take the above statement literally if one is referring to synthesized syllables which contain only two ferments; but, in natural speech, adj,~stments ox F2 are often closely paralleled by 142

TIIF. M A J O R

PIT('H

FEATUKE~

OF VOCALIC

Q, U A L I T Y

I4';3

higher formant arljustlnents, particularly of F3. However, this may" be a complication only at the acoustic stage of speech. At the auditory or perceptual stage tile hearer may receive a single pitch sensation, here called A-h, from a group of higher formants, that is, F2 plu; the higher formants mentioned above. A: least two types ot evidence suggest that this is the case. One is that the Nature c,f the human pitch scale (see Stevens and Volkmann 19401. would result in the perceptual 'crowding together' of the higher forrnants. The other is that vowels of good auditory quality can be synthesized by substituting a single formant, $2, for what one might call the F2 + group of formants (see, e.g., Delattre et aI., 1952: 2t0: or Arnold et al., 1958: t24). For the purpose of calculating ~he perceptually effective frequency of the F 2 + group of formants in nat~ral vowels, Fant (1959: 80) proposed a fort., ~la designed 'so as to :ake into account a gradual increase in the i; 1port~ nce of the third formant as F2 is raised in frequency'. He suggt:~sts that this calculated effective frequeocy, which he calls F2', ~hould replace F2 in two-dimensional acoustic plottings of vowe~s. Farlt's F2' may be regarded as that frequency which is the stirc~.~hts fo'c my proposed A-h pitch sensation in vowels. ~ao~her widely accepted feature o[ vowels seems directly ~'eiated tc~ the pitch sensation caused by FI. This pitch, here called A-1 (1 for lowest formant), serves to place a vowel in the 'high-low' or "openclose' dimension. Because art A-I versus A-h plotting of vowels takes into account the pitches heard on a human pitch scab.e, it should produce something closer to an auditory vowel space than dc,es any F I versus F2 plot, whether logarithmic or linear. However, further improvements can be made in the design of an auditory vowel space b:~ the addition of a third dimension. The new dimension, here called A-d, is based on the pitch di[[erence between A-I and A-h, the two pitch sensations described above. As was mentioned earlier, both Arabic flat (pharyngealization) and Russian sharp (palatalization) are easily handled in such a dimension. In particular, the addition of A-d enables one to produce a vastly simplified description ot the feature fiat which is very awkwaxd :o han~tle in terms of A..1 and A-h which cause the specificatio~ of fiat t,j change for each vowel, It seems that A-d, like A-I and A-h, is bgsieally a pitch sensation because all synthetic Arabic stimuli with A-d below approximately 400 reels were judged to be flat

1~4

t t A R O L D J. P A D D O C K

('emphatic') by Egyptian subjects, The above facts explain why Arabic 'emphasis', though cued by very different absolute formant frequencies in different phonetic contexts, still 'gives a strikingly unitary impression' (Harrell 1957: 69). Of course, two-formant synthetic vowels are most easily plotted in the proposed three-dimensional space because they require no calculating of the effective frequency which produces the A-h pitch sensation, For such synthetic vowels the two torm.xnt frequencies (in Hz), S~ and $2, can be converted directly into their corresponding pitci~es {in mels), A-1 and A-h. A-d is then found by subtracting A-t ~rom A-h. All sixteen vowels plotted in fig, I are in fact of this synthetic two-formant type; their symbols and formant frequencies are taken from Delattre et al. (1952: t98-199).

+d

A-h

•

-

,K

+

Fig. 1. Synthetic vowels in a proposed auditory vowel space.

Because of the relationship among the three proposed dimensions (i.e., A-1 + A-d -- A-h) andthe linearity of the scale (in reels), all sixteen vowels of fig. 1 fall in the same plane, What one might call the cardinal area of the above plane is outlined by heavy fines; broken lines indicate where this plane cuts the sides of ~ e threedimensional space outside the cardinal area. Articulator] constraints prevent vowels occurring at points like X and Z which are in the defined plane but 'in front of' the cardinal area. However, pharymgealization can cause vowels to occur at points like K and L

TH[

MAJOR PITCH FEATURES

OF V O C A L I C Q U ~ . L I T Y

145

which are in the defined plane but 'behind' the cardinal ~xea. In fact, K and L are approximately the auditory positioas reached by the 'en:.,pimtie' (i.e. fiat or phaG'ngealized} allophones of Egyptian colloquial Arabic /u:/ and [o:] respectively. This explailas Elmenoufy's (t963: 26) statement that such allophones 'are lowered or more backed'. The fact is that, in purely auditory terms, both lowering and retraction occur on such allophones. FURTHER RELATED EVIDENCE

The main supporting evidence for the theory proposed above is to be found in the vowei diagrams which have been used so successfull3, by ~.~uditory phoneticians. There are two main points to be noted here. The first is that traditional vowei diagrams have been useful despite the fact that they were plane, two-dimensional figures though much evidence indicates that there m-e three major pitch dimensi arts for vowel quality. Because vowels {at least all normal vowels, i.e. those non-nasal vowels formed by ,~abial and lingual gestures} have been shown to fall in the same 'auditory plane' (see fig. I), ~ two-dirneasional diagram can be a per/ectly adequate representation of ~Jxe"space' in which they are heard. The second point is that the proposed theory explai~,s the differences in shape wliich we /ind in the plane vowel diagrams used by diflelent ptmneticians. In such dia~arns the 've..'tical' or 'high-low' dimension seems to be directly related to A-I, the pitch of FI. Hc,wever, differences in the 'horizontM' or 'frontback' dimension indicate that phoneticians can direct their h~tening to one of three states for this dimension. Phoneticians who cone,~ntrate on the A-d sensation would produce vowel diagrams .~n which the "back' slopes slightly inwards as in fig. 2 (see, e.g., I P z ~ 1949: fi or Kurath ~;939: 123}. Those who listen to only A-h draw diagrams with the 'back' sloping outwards as in fig. 3 (see, e.g., Robertson and Cassidy 1954: 59). Others, who apparently compromise between their A-d and &-h sensations, would select a vertical 'back' (see, e.g., Gimson 1962:38 or Kingdon 1964: 1t4). The 'competition' of the A-h mad A-d sensations can explain why Ladefoged's (1967: 1.37) British phoneticians disagreed more 'horizontaUy' than 'vertically'. In the study o~ vowel quality mentioned above, Ladefoged also

I46

} I A R O L D J. P A D D O C K y

,,,

.... . .o. .~ "~o

~

¢

u

o'f

o

e

,~'

1560

3i°

• o "

Q, I!0

d

A ~

A !

0

. ~40

Fig. 2, Elimination of A-h. All numbers refer to pitches in reels. y

t,u

u

~6o

t

!

A-E

B20 ;~

a

t)

Q

h ..... mO Fig. 3. Elimination of A--d, All numbers refer t o pi'i:ehes in reels. 1920

A --

constructed a three-dimensional auditory vowel space (1967: 140), However, he concluded that the tradibonal articulatory labels of back/front, opon/ciose, and spread/rounded which he attached to the three dimensions oi his space were inappropriate ~or a truly auditory or perceptual vowel space. ~Vlypzoposed space (fig. i) may therefore be regarded as an attempt to satisly Ladefoged's proposal (~967: 140--141) for three purely auditory dimensions for such a space. I r i s significant t h a t my three proposed auditory dimens[gns do not bear a one-to-one relationship to the three: articttlatory dimensions rejec.ted by Ladefoged. One may particularly note that changes in the spread/rounded articulatory dimension usually cause changes in all three:of the auditory dimensions which I have proposed, This would account for the fact that Ladefoged's eighteen subjects (1967: t34), despite-the phonetic training of all and tlae extensive experience of some, disagreed widely as to the degree of lip-rounding in certain unfamiliar Gaelic vowels when judgements

THE MAJOR PITCH FEATURES

OF V O C A L I C Q U A L I T Y

147

were based solely on attditory evidence (Ladefoged 1967: 1&e~-136,

139-140). Hanson (1967, 1966) has also developed a three-dimensional auditory vowel space. His three vowel dimensions were derived from human ~nd synthetic Swedish vowg',s (1968: 99) 'in a large number ol experiments based on multidimensional scaling techniques -nd principal component analysis'. Hanson's (1968: 10~) FI and FII dimensions eorrespond to my A-h and A-I dimensions respectively. His third proposed dimension, F i l l , seems unsatisfactory for at least two reasons, One is that, unlike his FI and. FII and all three of my proposed dimensions, it 'is not matched by any s~mple acoustic parameter' (Hanson 1968: 101)~ Another is 'that Hanson's FIII distributes vowels in ways which oppc.se the, traditional usage of auditory phoneticians. For example, If] and [aj lie near one end of F i l l ; [¢] and [u] near the other (see Hanson. ~968: 100). It seems clear that such vowel pairs as [i-a] or [~-u] do hog share any obvious auditory feature. Unlike that t;t Hanson, the extens~.ve expe:imentalwork reported by Eli Fischer-Jorgen~en directly supports my proposed A-el di•mension. The lot!owing quotation from her findings is most relevant

0968: 97): There seems thus t o be ,~ p r e d o m i m m t dime asion, which c o m p a r e d t o t h e traditional vowel triangle can be said to r m t obliquely d o w n w a r d from t h e upper left c o m e r [i] to t h e lower right c o m e r Iv], corr~.ponding a p p r o x i m a t e l y to F2 minus F1 . . .

Her claim that this 'difference' dimension is the pr~lominant one is supported by the tact that my A-d dimension is longer than either of the other two. This may be seen in fig. 1, but a comparison of figs. 2 and 3 makes the difference between A-h and A-d more obvious. The actual lengths of the three dimensions on the pitch scale for the synthetic vowels considered in this paper are as follows: A-d = 1320 reels; A-h = 1I40 melt; A-l = 460 mels. Experiments relxJrted by Fourcin (196=,,) indicate that human hearers perform a similar complex analysis to derive the 'pitch' of noise which contains periodic spectral pea~. Fourcin's subjects performedpitch matching against such noise in which independent changes were made i n b o t h peak spacings vnd l~ak frequencies. The results indicated that neither frequency spacing nor absolute

148

H A R O L D ], P A D D O C K

frequency was entirely responsible for the subjects' pitch sensation, but that an alteration in either could cause a change in the 'pitch' heard. These findings concur with the fact that vocalic cues are perfectly audible r~,itkin isolated (i.e., witbout accompanying vowel transitior, s} voiceless fricative consonants, which have only a noise source, in Russian (see ~upljakov 1968) and Arabic, languages in which some vocalic contrasts have been traditionally assigned to consonants. RELEVANCE TO DISTINCTIVE FEATURES TtIEORY

"[he facts reported above throw some light on ]akobson's three oral resonance dimeusions (see Jakobson and Halle 1956: 40-41} which we may cMl (l) flat-sharp, (2) acute-grave, and (2) compactdiffuse. As was point(:d out by Fry (1956), one of the main faults of the Jakobsonian approach to distinctive features was the inexplicitness as to which st~tgc (a~ticulatory, acoustic, or auditory]perceptual) of the speech chain the features should apply. It now seems clear that the features suggested by any one stage do not correspond uniquely to those suggested by any other stage. For example, the three auditory dimensions of vocalic quality which I have advocate,.i above have no one-to-one correspondence with such useful argiculatory dimens~.ons ,as high-low, back-front, rounded-spread (cf. Chomsky and Halle 1968:298--311), nor are they directly suggested by art independent study of the acountic,evidence. However, tl'.e three m~i$ory vocalic dimensions which are suggested in this paper do correspond in an interesting manner to Jakobson's three oral resonance (i.e., vocalic} dimensions mentioned above. In fact, one could now redefine the above three Jakobsonlan parameters in purely auditory te~'ms so that: (1) compact-diffuse (9.) acute-grave and (3) sharp-flat

equals + A-1 equals + A - h equals + A - d -

This correspondence suggests that Jakobson's oral resonance features were based on some intuition about his own perception of vocalic quality (cf. Hockett 1955: 172-178} rather than on any direct acoustic or articulatory evidence. Their faiba~e to concede this fact was a major fault in the distinctive feature formulations

THE MAJOR PITCH FEATURES

OF V O C A L I C Q U A L I T Y

I49

of Jakob~on and Halle and, in addition to generating much fruitless controversy, led to problems such as those mentioned below. One result was that the acoustic evidence as presented was sometimes more of a liability than an asset. This was, for example, the case with the features which Jakobson places under the heading of tonality; that is, the features of grave (vs. acute) ; sharp (vs. plain) and fiat (vs. plain). The acoustic correlates given in the Preliminaries (Jakobson et al., 1952: 29.-36) are vague but effectively the same for all three features. Even greater vagueness concerning the acoustic cues for those feature~ is found in the Fundamentals (Jakobson and Halle 1956: 3I). The acoustic e~denee as given certainly does not support the se'tting up of three tonality fea~,ur~:s. Hcwever, the reformulati~m of the acoustic evidence which has been' sug~'ested by my experiments does support two pitch dimensions, A-h and A-d, which correspond to Jakobson's two tonality dimensions. A quotation from Martin Joos's review o| the F~ndamentats seems appropriate here {Joos 1957: 412); . . . we h a v e m u c h t o leax~ - on o u r o w n t e r m s , of course - f r o m J a k o b s o n ' s pola'" t h e o r y of phonology. W e might, as a m ~ e r of fact, u l t i m a t e l y arrive a t a fai::ly close a g r e e m e n t vdtJa his conclusions, B u t we'll h a v e to a r r i v e t h e r e b y our own road, a n d J a k o b s o n a n d his disciples will j u s t h a v e t o be p a t i e n t w i t h us meanwhile. Once axrived there, w~ should n a t u r a l l y a c k n o w l e d g e h o w he has stimulated us to p r e f o r m t h e crucial expe.~naeats.

Another result was that the lack of eorrespondance between some of his Ieat,~res and traditional axticulatory distinctions caused Jak.)bson to erroneously combine several of the latter within one of his proposed oppositions. For example, after an invalid appeal to the principle of complementary distribution (p. 7), the authors of the Preliminaries manage to combine lip-rounding, pharyngealizat~,on, and retrofle~on within the same oliposition of flat vs. plain (p. 34). Their complementation principle that no two of the above articulatory features occur in the same language is seen to be violated: thus, in my own dialect of English lip-rounding and retroflexion contrast directly in minimal pairs such as quick [kwik/ versus crick [krik[; and irt trying to synthesize Arabic pharyngealization, I found that lowering of F1 (in addition to F2) was immediately reje&ed by Arabic subjects as rounding (i.e. Iwl) rather than 'emphasis'.

ISO

HAROLD

J. P A D D O C K

By restricting themselves to the articulatory correlates of their reformulated distinctive features, Chomsky and Halle (I968) effectively avoided the problems of having to establish the reality oI their proposed features at other stages in the speech chain. However, this avoidance is not given as the reason for their decision (see Chomsky and Halle 1968: 299).

Phonetics Department, University College, Gower 5tre~t: London, England, REFI?.RENCES ARNOLD, G. F., P. DI~NEtl, A. C. GIMSON, J. D. O'CoNNER and Jo L, M. T~tM, 1958. 'The synthe~i~ of English vowels', Language and Speech 1, 114-125. CHo~aSKY, N. aRd M. HALLE, t968. The ,ourd patler,¢ el E*agBsh. New York a~ud. London, Harper and Row. DEr.ATTRE. P., A. M. LIBERMAN, F. S. COOPER attd L J. GRRSTKA~[, 1952. 'An experimental study off the acoustic determJnamts of vowel color; observations oi one- and two-formant vowels synthesized from spectregraphic patterns', Word 8, 195--2t0. E..a~z~ouFY, A. M, E., 1963. A prosodic approach ~o Eg~$ia~ colloquial Arabic. Unive~mty of Edinburgh, School of Applied Linguistics (Dinner. ration). FANT, G., 1959. 'Acoustic aaxaJysisand synthesis of speech with applications to Swedish', E~i~son Teal~ics 15, 3-108. FISCHER-JdRG~;N,,iEI~,E., 1968. 'Perceptual dimensions of vowels', Z P S K 21, 94-98.

FouRcxN.. A. J , 1965. 'The pitch of noise with periodic spectral pe~ks', paper B42 in Vol. la of P~,oceedi~gs o] tt~e Fifth Inter,rational Acoustics Co#gr~ss (1"hone, Liege). FRY, D. ]3, !956, "Perccptiou and recognition in Speech', in: ItalM, Morris et al., eds., For Roman Jahobson. The Hague: Mouton axtd Co, GIMSO1,LA. C., 1962. An i,,troduclion to the pronunciation o] Eugtish. London, Edward Arnold. HAt~so~, G., 1967. "Dimensions in speeclt Sound lvsrc~ption. An experimental study of vowel perceptiort', E~'i~sson Technics 23, 1-175. IIANSO,'~, G., 1968, 'Distinctive features and response dimensions of vowel perception', ZPSK 21, 99-101. HARRELL, R. S., 1957. The phonology o/colloquial Egyptian Arabic. American Council of Learned Societies, Program in Oriental L a ~ a a g e s , Publications Series, B-aids-9.

THE MAJOR PITCH F E A T U R E S OF VOCALIC Q U A L I T Y

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HocK,.'xx, C. F., 1955. A manual o/phonology. Memoir 1!, LJ.A.L. IPA, 1949. The pvinc~iples o] the international phonetic association. I.xJndon, Depa~tuaent of Pho:aeties, University College. JAKOBSO~, R., G. FAN'r and M. HALXaL 1952. Preliminaries ~ospeech a~a~ysis. Cambridge, Mass,, ~I.I.T, Press. Ref. to 1963 printing, JaKoBso~¢, R. and M. HAu.z, 1956. F,~ndamentals oI la~lguage. The Hague, Mouton and Co. Joos, M., 1957. Review of Roman Jakobson and Morris Halle, Fu~lda~.'e~j~als o/Language {1956} in Language 23, 408-415. KmGUON, R., 1964. 'The representation of vowels', In Honour o/ Daniel Jones, London, Longm~Lns, pp. 112-115. KURaTH, H., 1939. Harulbook o/ the ling~is¢ic geography o/ New England. Providence, R.I., Brown U, Press. LA~GOFED, P., 1967. 'The nature of vowel quality' in.: P. Ladegofed, Three areas o/experimental pkoneti~, London, Oxford University Press, pp. 50-142. ROS1~gTSOlq, S. a - d F. G. CASstD¢, !954. The development o/modern English. Englewood Cliffs, N J., Prentice-HalL STEvEns, S. S. and J, VOLKMANN,1940. 'The rda~ ~.~:,of pitch to frequency: a revised scale', A.merican Journal o/Psychology $3, 329-353. gUPLJAKOV, V. S., 1968. 'Pitch and hard-soft dis%~ction of fricative consonantz ] s / a n d l~t', Z P S K 21, 77-152. ZPSK

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