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Comparative phonetic vowel analysis
Journal ofPhonetics (1973) 1, 249-261
Comparative phonetic vowel analysis F. J. Koopmans-van Beinum Institute of Phonetic Sciences, University of Amsterdam Received 13th October 1972
Abstract:
This paper aims at providing a contribution to the drafting of a method of comparing the speech of a certain place or district with the speech common to the country in a significant way, making use of means and possibilities which are at the service of modern experimental phonetics. In order to obtain some concrete material a Dutch dialect, viz. the dialect of the province of Utrecht, was compared in certain aspects with non-regional Dutch. The formant frequencies and the duration of the 12 vowels of statistical data processing. It was evident that the formant values of two groups of speakers were measured and compared on the basis of the vowels alone were enough to make a distinction possible between the Utrecht dialect and non-regional Dutch and that, where necessary, duration and formant frequencies appeared to supplement one another.
Introduction
In 1966 the contents of two papers read to the Dialecten Commissie of the Koninklijke Nederlandse Akademie van Wetenschappen appeared in print entitled Utrechts, as well as the discussion which resulted from both lectures. One of them was written by T. van Veen (1966: Utrecht as Transitional Dialect). Some four assertions by van Veen were the immediate cause of the investigation described below. As characteristic phenomena of the dialect of Utrecht he mentions among other things: " ... the rather more open pronunciation of the oo, especially before a dental as in sloat, schoal, oalie, !waning. In standard pronunciation of Dutch we hear this sound before r: voor, boor. Sometimes this oo sounds slightly diphthongized" (approximately the vowel of English Maud); " ... the rather more closed pronunciation of the ee, especially before dentals: steen, been, geen. In standard Dutch this pronunciation is common before r: beer. This ee too is often slightly diphthongized .. ." (approximately the diphthong of Scottish Ian); " ... drawing out of the short ii especially before n +dental: !wand, braand, kaant. Gelderland, Brabant and the provinces lying in the eastern part of the Netherlands have this lengthening too. Short ii is also lengthened before other consonant combinations ... ;" " ... the rounded pronunciation of aa as ao in originally long aa (schaop) as well as in the in open syllable lengthened ii (waoter ) .... " Without discussing either these characteristics or the terminology, a clear resemblance can be shown to exist between these assertions, to wit in the first two phenomena explicitly and in the second two phenomena implicitly a comparison is made with vowels of standard Dutch. Van Veen does not give the impression of having done experimental phonetic investigations prior to his paper, although he suggests a comparison of Utrecht with standard Dutch vowels. I am of the opinion, however, that, if a Dutch dialect is compared
250
F. J. Koopmans- van Beinum
in a significant way with non-regional Dutch, a method has to be developed so that, where possible, use is made of modern apparatus and advanced data processing techniques for all aspects of this dialect as well as for Dutch which are of importance for such a comparison. (The term "Dutch" will from now on be used to denote "Dutch without regional characteristics"). Research Problem
In an investigation aimed at comparing vowels, attention will have to be paid to a number of characteristics of vowel phonemes relative to the language areas involved such as, for instance, formant frequencies, duration, intonation phenomena, or whatever else is thought to play a part. A further point of investigation would have to be to see if vowels in connected speech differ and, if so, in what respect they do so from vowels pronounced separately. As a simultaneous enquiry into all these aspects would be too comprehensive, attention was focused in the first instance on the formant frequencies and the duration of the vowels in disconnected words, particularly since these are the two aspects which were raised by van Veen , even if in slightly different wording. Phoneticians are generally agreed that vowels can be described in terms of formants (F1 and F 2 ). As regards the content of the notion "formant" there is, however, some difference of opinion. A formant is defined either as a resonance frequency, or as a maximum in the spectrum and therefore as a whole multiple of the basic frequency of the vocal cords, or as the natural frequency of a free resonance of the vocal tract. The measuring apparatus to be used depends on the definition chosen. lf the first is chosen then measuring is only possible after resorting to surgical intervention (cf. van den Berg, 1953). For the second definition, use is made of a filter spectrograph with which a spectrum is made and the relative maxima are measured. It is unlikely that the ear operates in the same way as a filter spectrograph. The third definition of the formant conforms with the way in which the vocal tract is brought into vibration by the pulses of the vocal cords and moreover this definition tallies with the possibilities of the ear as demonstrated by the measurements of Tasaki (1954). This definition (the frequency of a damped natural frequency of the vocal tract) was selected for this investigation. One of the consequences of this choice is that measurements have to be taken directly from a sound curve and that making use of a spectrograph does not suffice. The only information to be gained by the use of a spectrograph is the area in which the formants are situated. lf one bears in mind that the basic frequency of the female voice lies around 250Hz and that therefore with this measuring technique multiples of 250 Hz formants only can occur, it becomes clear without too much calculating that mistakes of 125Hz are by no means unlikely. As some vowels have F 1 or F2 values which are separated from contrasting vowels by barely 100 Hz, it will become clear that for a comparison of vowels of a dialect with those of Dutch and for locating shifts in the formant field spectral measurements yield information of too limited a nature. Method of Data Collecting
As for a significant comparison the groups of speakers have to be as homogeneous as possible, this investigation of the Utrecht dialect confined itself to the dialect of the villages Maarssen and Breukelen, and, for Dutch, non-regional speakers were selected.
251
Comparative phonetic vowel analysis
Three years ago a preliminary investigation was carried out for which 12 vowels of ten male and ten female students of a secondary school from Maarssen were measured as regards their formant frequencies. On the basis of statistical evidence these were compared in respect of formant frequencies to the corresponding vowels of a non-regional speech group of Dutch, consisting often male and ten female university students from Amsterdam. At this point it should be mentioned that standard Dutch has 12 monophthongs and three diphthongs. The results of this inquiry (Koopmans, 1970) appeared to merit further investigation with new groups of speakers. Utrecht In cooperation with D. Dekker and J. Compaan, both teachers from Maarssen, taperecordings were made of ten men and ten women between the ages of 25 and 65 years, all born and brought up in Maarssen or Breukelen. In order to prevent the influence which a written text might exert, pictures were used of those items which contained the desired vowel (according to a consonant-vowel-consonant pattern or a vowel-consonant pattern). The necessity of making pictures somewhat confined the choice of the key-words. The words were chosen on the advice of J. Daan, head of the Institute of Dialectology in Amsterdam, while the pictures were designed especially for this investigation by W. A. van Herpt. The tape-recordings were made with a portable tape-recorder (Nagra III, model NTPO, with a Sennheiser microphone, type MD 31 HN) and magnetic tape (Scotch low-print); speed 19 cmfs. The subjects of the experiment were orally instructed to name the objects which they were shown. In order to familiarize the speakers with the procedure the whole sequence of pictures was gone through once beforehand, whereby care was taken that the leaders of the experiment did not themselves name the objects. A phonetic notation plus pertaining key-words follows, as used in this report from now on:
[u] in [o] in [;, l in [a]
Ill
[a] in [ii l
Ill
[oJ
Ill
[d] Ill [i] Ill [I] in [e] in [E] in
hoed poot hok tak haak muur neus put tien kip een hek
(approximately the vowel of English (approximately the vowel of French (approximately the vowel of English (approximately the vowel of French (approximately the vowel of French (approximately the vowel of French (approximately the vowel of French (approximately the schwa of English (approximately the vowel of French (approximately the vowel of English (approximately the vowel of French (approximately the vowel of English
book ) beau ) hot ) las ) grave) mur ) peu ) amber) ) si lip ) ne ) set )
Dutch For the preliminary investigation (see above) as regards data collecting for Dutch, use was made of material already available at the Institute of Phonetic Sciences. However, the method of data collecting differed greatly from that used for getting the Utrecht material. Therefore recordings were made for the present investigation of a new standard group for Dutch and here, too, use was made of the same material and with the same instructions as described in the preceding paragraph for the Utrecht group. The only point of difference
252
F. J. Koopmans-van Beinum
that should be mentioned is that the Dutch recordings were made at the Institute of Phonetic Sciences with an Ampex tape-recorder (type 300) and a Philips microphone (type EL 6031/00). The problems connected with the composition of the standard group will be dealt with below. Measuring of Utrecht and Dutch material Copies were made of the recordings described above which were rendered on a tape-player with rotating play-back head (developed at the Institute of Phonetic Sciences at Amsterdam) in order to measure formants (F1 and F 2 ) and duration of the vowels. One of the possibilities of this apparatus is an unlimited repetition of a very small, carefully chosen segment of the recorded signal. This meant that for the present investigation it was possible to "lift" the vowel under scrutiny out of its consonant surroundings, so that the sound curve of this vowel segment alone could be made visible on the screen of an oscilloscope. For this purpose a storage-oscilloscope was used (Tectronix, type RM 564 with an amplifier, type 3A72 and a time-base, type 3B3), which stores the sound curve on a phosphorescent screen, so that measurements can be taken directly from the screen. The starting-point, viz. the fact that a sound curve of a vowel is composed of natural frequencies (F1 and F 2 ) superimposed on one another, suggested a method of formant measurement from the distribution of zero-crossings. The duration was measured in ms; the beginning of the vowel was chosen at the point where the formant pattern was clearly visible for the first time and the end was taken to be that point where the pertaining pattern disappeared. = - f'--1 (\ 1\ "'QV\j\.JV" L',
C\ <'>
II
0=
/'VVJ
v
(\~ \Jv
M f\-1\t[\~AD-=~ \JW V
-h·
~v
i~J
~ F
Figure 1
1
F,
Three parts of the sound curve [a] in tak pronounced by one of the Utrecht informants taken from the oscilloscope. The third curve shows the zerocrossings of F1 and Fz.
Material Processing The IBM 1130 computer of the Institute of Phonetic Sciences was used for the complicated processing of the data. The special character of the problem posed made an increase of the program library necessary. The statistical programs were written by the author of this report, the plot-programs by Ir J. G. Blom; programs were Basic Fortran IV.
Comparative phonetic vowel analysis
253
Input and processing For each speaker of Utrecht as well as for Dutch the values of F 1 and F2 and the duration of the 12 vowels were punched on cards. After this the following processing took place. Separate computation of mean values and standard deviations of F 1 and F 2 and of duration/vowel were carried out for the Utrecht groups of men and of women as well as for the Dutch groups of men and of women. The results are shown in Tables I, II, III and IV respectively. The reason the data for men and for women were processed separately is the fact that the formants of speakers with conforming articulatory configuration are inversely proportional to the length of the vocal tract (cf. Mol, 1963). In Fig. 2 the average formant frequencies for the four groups have been plotted in form ant fields. F2 0 0 <.D I
0 0
OJ I
Q
0 0
~
0 0 ~
Q2
I
I
I
I
I
3oo r-4o or--
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oe
600 r-
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N I
0 0 <.0 N I
(Hz)
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ro
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0 0
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0 0
0
0 0
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N N
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ei
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ue
ec
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oe oe Je
e !:
ae
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0 0
0 0
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oe
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ee
••
00
800 rMean formant va lues of the Utrecht group of moles
900 r-
Mean forman t va lues of the Utrecht group of females
g "--
I
300 r400 r5oo r-600 700
I
u.
ue
,.
ile ;~e
oe
el
.
•e
,
ue ae
800 900
Figure 2
I
I
I
I
I
I
I
I
~·
.o
I
I
I
ei
Mean formant values of the Dutch group of moles
i.ie
ue oe
.
,
oe
ie el
ee
••
•• Mean formant values of the Dutch group of females
Mean formant values for the four groups plotted in formant fields.
Computation of the correlation coefficients of F 1 and F 2 of the 12 vowels for the four groups mentioned above (cf. Tables I, II, III and IV), and plotting of the distribution of the vowels was carried out. The ellipses indicate the areas embracing 50% of the realizations if a normal bi-variate distribution is assumed. Figure 3 shows the ellipses for the Utrecht group of males (shaded) and for the Dutch group of males (not shaded), Fig. 4 gives the ellipses for the Utrecht group of females (shaded) and the Dutch group of females (not shaded). The vowel symbols in the ellipses signify the vowels as pronounced in the given key-words. Comparison of the mean values of F 1 and F 2 for the various groups (Dutch and Utrecht) with the aid of the Student's t test (cf. Table V). At the significance level of 5% and with 18 d. f. we get t = 2·10. This implies that where values have been found fort > 2·10 we are dealing with a 5% probability level that deviations are due to chance. Significant values of t for 5% P-values have been underlined. At a significance level of 10% and with 18 d.f. we get t = 1·73. Significant values of t for 10% P-values have been underlined with a dotted line.
F. J. Koopmans-van Beinum
254
F 2 (Hz) 0
0
0 0
0
8
tl)
(\j
tl)
r:::
lQ
0
8
(\j
(\j
8
0
§
(\j
r
iC
tl)
300
Q)
®
400
~
500
:I! lC
600
\~
700
800
900
Ellipses of the formant areas embracing 50 % of the realizations assuming a normal bi-variate distribution. ll!tl, Men Utrecht; D, Men Dutch.
Figure 3
0
tl)
1'-
§
0 tl)
~
8 tl)
0
0
@
(\j (\j
0
tl)
8 tl)
(\j
300
400
500
I' [,__-
600
700
Figure 4
Ell ipses of the formant areas embracing 50% of the realizations ass uming a norma l bi-variate distribution .ll!tl, Women Utrecht; D, Women Dutch.
255
Comparative phonetic vowel analysis
A negative sign before the t-values shows that the mean formant frequency of the Dutch value is smaller than the mean Utrecht value. It should be borne in mind, however, when considering the table that a formant is one aspect of the vowel only and that each vowel is always part of a whole vowel system. Comparison of the mean values of the duration of the various groups (Dutch and Utrecht) with the aid of the Student's t test, in the same manner as described above (see Table VI). Significant values oft for 5% P-values have been underlined in the table, for 10 % P-values they have been underlined with a dotted line. A negative sign shows that the average duration for the Utrecht group is greater than for the Dutch group. A graph shows the duration of the vowels. The computed mean values for the duration of the vowels as pronounced in the given key-words, were illustrated for both groups of males and those of females (Figs 5 and 6).
280 270 260 250 240 r230f22012101200 1-
"' E
19o r1801I 701160 150 140 130 120 110 100 90 I
{)
Figure 5
e
I a
I
!
I
I
I
{l
u
1
u
='
:t
1.
u
I
Mean values of the vowel duration in the given key-words. - -, Men Dutch; - - - -, Men Utrecht.
Results and Conclusions
Results All results are summarized in tables, figures and appendices. The appendices (drawings used for the test, data concerning speakers, values measured/speaker, computer programs) are all to be found at the Institute of Phonetic Sciences ofthe University of Amsterdam. Conclusions When drawing conclusions from the above described results it should be realized clearly, that notwithstanding the approximately 1500 measurements, the material is rather limited. After all, for each vowel only one key-word of each speaker was recorded.
F. J. Koopmans-van Beinum
256
240 230
\;\ . \
e
I
\
\
220
~~,
I
~
I \
I
2 10
• I
200
"' E
.
I
\
I
I
I
190
I I
ISO
I I
170
~I\•
160
/.\
150
I
I
140
............,
130
\
120 110
·-·-..--•\ .... .
'·-------
\ \
•
100 90 i: i
Figure 6
c:
~~
o
U
i
u
,"'l
.1
1:
u
I
Mean values of the vowel duration in the given key-words. - - -, Women Dutch;-- - -,Women Utrecht.
The results that have been found are therefore always linked to key-words, that is to say to certain consonant surroundings of the vowel. This is not a serious disadvantage for formant measurements, as the influence of the bordering consonants on the rather constant middle section of the vowel is small in words pronounced in isolation. Even in the case of a vowel followed by [r] no particular deviations occur (see Koopmans, 1969). The duration of the vowels is probably influenced much more by the consonants. As long as an investigation (still in a preparatory stage) has not been completed, the conclusions that can be drawn will have to be taken to pertain only to the vowels in the key-words, as used here. Another consideration should be that the vowels have been indicated with phonetic symbols, but this is meant to signify only vowels as pronounced in these keywords. Tables I, II, III and IV record the mean values/vowel and the standard deviations of F 1 and F 2 and the duration as well as the correlation coefficients between F 1 and F 2 (necessary for the drawing of the ellipses) for the four groups of speakers. A large standard deviation for a certain vowel points to the fact that the speakers of a group differed rather a lot in their pronunciation of the vowel. In Fig. 2 the mean formant frequencies/group were set out in formant fields. The system of axes has been chosen, as is usual in the case, so that the vowel triangles that are formed correspond with the vowel triangle as given by Hell wag (1781). The following can be concluded as regards the vowel triangles in Fig. 2: (a) The same vowel triangles are found, roughly speaking, for speakers of Utrecht as for the Dutch speaking group. This points to the fact that both groups use their articulatory organs in almost the same way. Something that is not to be wondered at. (b) The Dutch speaking group has vowel triangles which are larger than those o(Utrecht
Comparative phonetic vowel analysis
257
speakers. This points to the fact that the Dutch group makes larger contrasts between the various vowels. (c) For.the Utrecht speaking group the vowel of tak lies more in the direction of Dutch [~>]in hek in the formant field than this is the case for the Dutch speaking group. Whether · this phenomenon can be called "palatalizing" is still questionable as no investigation was made here as to the place of articulation and the articulatory movements. Besides, it is a well-known fact that, with totally different articulatory positions, [~>] especially can be realized with identical formant frequencies (cf. Mol, 1966). (d) For the Utrecht group the vowel in haak has, as regards the average formant frequencies, practically the same position as the vowel in tak for the Dutch group. (e) For Utrecht speakers the first formant of the vowel in neus and the one in een have considerably higher values than for Dutch speakers. The cause is the marked diphthongization of the Utrecht pronunciation of these vowels. The Dutch group shows a shift of the first formant only at the end of the vowel, whereas the Utrecht group has a greater formant-shift during the whole of the vowel signal. This last statement demonstrates a weakness of the method described in this report. This processing method is based on the fact that Dutch vowels are, generally speaking, rather constant so far as their formants are concerned. One measurement taken from the middle of the vowel signal can be regarded as being representative of the whole vowel signal. Thus it becomes possible to set out the vowel phonemes in a two-dimensional formant field. But in the case of diphthongs and strongly diphthongized vowels measurements should be taken in quite a number of places in the vowel signal, and both formant-shifts and the speed of shifting in relation to the total duration should be taken into account in the actual processing as well as in the illustrations. The complications resulting from such an approach would be so many that it was decided, for those vowels that were strongly diphthongized, to process one measurement only, viz. from the middle of the vowel signal. It should be borne in mind when considering the results that the vowels of neus and een for the Utrecht group and the vowel of poot for most members of this group showed considerable first formant shift and that formant frequencies indicated represent in fact one moment in the middle of the shift. In Figs 3 and 4 ellipses have been drawn for male and female speakers respectively, embracing 50 % of the realizations based on a normal bi-variate distribution. As the ellipses are drawn round the mean formant frequencies the same conclusions are valid as for Fig. 2. For 3 and 4 the following must be added. (a) The ellipses for Utrecht speakers are generally speaking larger than those for the Dutch speaker group. The greater range can be accounted for by and large, by the diphthongization mentioned above. (b) For the Dutch group the vowels [o] in pool and[<>] in hok together, [o] in neus and [;}]in put together, [e] in een and [1] in kip together, and for female speakers [a] in haak and [a] in tak together show an amount of overlap, which is cancelled, however, as will be shown later by differences in duration. (c) The Utrecht group of male speakers show hardly any overlap, in the corresponding group of female speakers, conforming slightly more to the Dutch speaking group, there is overlap for the vowel of poot with that of hok, the vowel of haak with that of tak, and the vowel ofneus with that of put. Here, too, the differences in duration have a compensating influence. Table V shows the computed t-values for men and for women for the mean values of the first and second formants. The signficant values given there confirm the conclusions drawn above. 15
258
F. J. Koopmans-van Beinum
Table VI shows the computed t-values for men and for women for the duration of the vowels. In Figs 5 and 6 the mean values have been pictured. We can draw the following conclusions. (a) The average duration of the vowels for Dutch speakers is greater than for Utrecht speakers. It is possible, here too, just as for conclusion (b) above, that the cause is the more careful articulation of the Dutch group. (b) The average duration is greater for women than for men. (c) A division can be made for all four groups between longer vowels ([6], [a], [e], [o]), and shorter ones([;}], [;,],[~::],[a], [r]), with in between [ii], [i] and [u]. But for the Utrecht speaking men the vowel in hoed [u] joins the shorter vowels, as do the ones for Utrecht speaking women in hoed [u] and tien [i] . For reasons stated above (material being of too scanty a nature) it seems unjustified to draw further specific conclusions as regards absolute duration of separate vowels and their t-values. (d) There is no reason to talk of "lengthening" of the [a] in the Utrecht dialect as was done by van Veen (cf. Introduction). (e) If one considers Fig. 5 in conjunction with Figs 3 and 4 the following conclusion can be drawn. For Dutch as well as for Utrecht speaking groups, for those cases where two vowels overlap in the formant field these vowels are far removed from in the duration graph (cf. [r] and [e]; [;}]and [o]; [;,]and [o] ; [a] and [a] in Dutch), suggesting that duration and formant frequencies complement one another where necessary. Discussion
The investigation described above is an attempt at comparison, at least for certain aspects, of speech sounds of a dialect with the standard pronunciation. The term dialect is defined as follows by van Dale (1961): (1) "the special speech of an area or of a place in so far as it differs from the general speech or from that of the country", and (2) as being: "each of those languages which originate from a common parent language" . The first definition reflects a synchronic, the second a diachronic approach, but in either definition the relation to the general speech or to the parent language is referred to. It will be clear that for a comparative phonetic investigation of speech sounds only the first meaning is of importance as a rule. Unless, of course, a comparison between two dialects is wanted based on their common parent language which itself is more likely to exist only in written form. For Dutch and its dialects the synchronic approach will, as a rule, be of most interest to the phonetician, which means that the relation of a contemporary Dutch dialect will have to be compared with present-day standard Dutch. Norm-group
There will, generally speaking, be no difficulties when forming a group of dialect speakers, as the dialect under investigation is by definition determined by the area or the place. Forming a norm-group for standard Dutch poses a far greater problem. How should such a group be composed or who composes this group, for it can not be denied that the "how" depends on the "who"? One possible way to circumvent this is to take a representative sample of the population of Dutch adults. The private opinion of every judge is kept out of consideration. This is, however, a rather unsatisfactory procedure, as a kind of "average Dutch" can be determined in this way, but it is unlikely that any person can be found who, in fact, speaks this "average Dutch" .
Comparative phonetic vowel analysis
259
If the judgment of one or some people is taken into account, the composition of a normgroup becomes an extremely arbitrary affair. This procedure was, however, used in this investigation as no suitable alternative method exists. A third, possibly the only acceptable, alternative is to do justice to the opinion of as many judges as possible. This involves an mvestigation of the manner in which the judgments were made. Also the matter should be gone into in how far one can possibly form a norm-group of speakers on the basis of judgment criteria. An extensive investigation is in progress at the Institute of Phonetic Sciences concerning these problems. The Follow-up It would be desirable to repeat the investigation as described above with large groups of speakers and with a great number of key-words. To what extent speech sounds in connected speech differ from those in separately pronounced words is a further point to be gone into. At the moment the measuring, as such, involves so much labour, that this can be done extensively only when the measuring process has become automated. Table I Men Utrecht. Mean values and standard deviations of Fl> F 2 and of duration; correlation coefficients of F 1 and F 2
Mean F 1 (Hz) [u]
[o] [;,] [a]
in in In
in
[a]
In
[U]
in
[oJ
In
[;)]
In
[i]
in
[I)
m
[e)
in
[c]
In
hoed poot hok tak haak muur neus put tien kip een hek
389 497 577 682 690 359551 468 336 403 492 610
F,
Mean Fz
(Hz)
(Hz)
F2 (Hz)
31 35 49 73 82 39 72 52 30 37 76 103
818 976 977 1451 1197 1874 1688 1698 2276 2199 2076 1934
82 93 86 109 142 150 143 193 174 182 144 175
S. D.
S.D .
Cor. coeff. - 0·034 0·615 0·612 0·513 0·721 0·045 0·386 0·100 - 0·068 0·148 - 0·085 - 0·138
Mean dur.
S. D.
(ms)
(ms)
107 186 116 105 214 168 208 106 147 96 195 99
19 16 18 21 34 30 24 16 25 17 16 19
Table II Women Utrecht. Mean values and standard deviations ofF,, F 2 and of duration; correlation coefficients of F 1 and F 2
Mean F 1 (Hz) [u]
m
[o]
In
[;,] [a]
[oJ
in in in in in
[;)]
In
[i]
In
[a] [U]
[I)
In
[e)
lil
[c]
in
hoed poot hok tak haak muur neus put tien kip een hek
419 597 653 758 722 393 562 497 394 450 550 693
F1 (Hz)
S.D.
33 66 102 79 111 39 75 63 28 37 66 73
Mean Fz (Hz)
Fz (Hz)
869 1030 1126 1462 1303 1919 1965 1977 2646 2540 2407 2216
79 144 116 141 164 143 58 81 58 74 108 159
S.D.
Cor. coeff. 0·395 0-413 0·082 0·741 0·494 0·257 - 0·241 0·544 - 0·543 - 0·134 - 0·021 - 0·017
Mean dur.
S.D.
(ms)
(ms)
133 207 119 124 244 170 232
33 33 33 24 37 42 29 27 30 28 45 32
118
139 112 215 120
260
F. J. Koopmans-van Beinum Table III Men Dutch. Mean values and standard deviations of Fh F2 and of duration; correlation coefficients of F1 and F2
Mean F1
Fl (Hz)
S.D.
(Hz)
[u] [o] [:>] [a]
[a] [i.i]
[o] [;J]
[i] [I] [e] [e]
in in m
in in in in in in in in in
hoed poot hok tak haak muur neus put tien kip een hek
25 44 67 33 39 31 55 30 25 22 37 39
334 464 538 639 738 308 406 436 306 374 403 618
Mean Fz (Hz)
F2 (Hz)
813 899 928 1292 1409 1819 1650 1596 2494 2196 2218 1877
71 85 94 86 77 138 83 116 126 115 130 98
Mean dur. S.D. (ms) (ms)
S.D.
Cor. coeff.
0·380 0·635 0·537 0·254 0·069 - 0·359 0·088 -0·022 - 0·414 - 0·615 -0·402 0·201
141 206 124 111 211 191 224 125 148 104 215 117
9 29 22 21 42 40 41 13 30 16 44 20
Table IV Women Dutch. Mean values and standard deviations of F1 , F2 and of duration; correlation coefficients of F1 and F2
[u] [o] [:>] [a]
[a] [i.i]
[o] [;J]
[i] [I] [e] [e]
in in in in in in in in in in in m
hoed poot hok tak haak muur neus put lien kip een hek
Mean F 1
S.D. Fl
Mean F2
(Hz)
(Hz)
(Hz)
F2 (Hz)
403 505 605 757 855 371 495 488 376 448 475 753
20 59 83 65 79 32 67 38 29 47 43 52
851 926 995 1277 1439 2064 1914 1788 2734 2594 2527 2231
69 61 86 137 128 158 135 90 139 103 114 172
S.D.
Cor. coeff.
Mean dur. (ms)
(ms)
168 248 137 .138 267 216 283 138 155 125 244 135
29 36 20 15 27 46 36 25 34 19 38 18
-0·239 0·745 0·501 0·671 0·441 - 0·314 -0·269 -0·080 0·234 0·312 0·622 0·283
S.D.
Table V t-values computed for the mean vowel formants of Dutch and Utrecht men, and for the mean vowel formants of Dutch and Utrecht women
Men Dutch and Utrecht t (Ft) t (Fz) [u] [o] [:>] [a]
[a] [i.i]
[o] [;J]
[i] [I] [e] [e]
in in in in in in in in in m
in in
hoed pool hok tak haak muur neus put tien kip een hek
-4·19 -1·73 -1·38 -1-61 1·55 -3·06 -4·82 -1·62 -2·27 -2·03 - 3·13 0·21
-0·13 -1·82
_.j:J.s
-3-41 3·93 -0·80 -0·69 -1·35 3·03 -0·03 -2·32 -0·85
Women Dutch and Utrecht t (F1) t (F2)
-1·25 -3·12 -1 ·10 -0·02 -2·93 -1·33 -1·98 _(j:j()
-1·28 -0·09 -2·86 1·99
-0·51 -1·99 - 2·70 -2-81 1·95 1-04 -1·04 - 4·68 1·74 1·29 2·29 0·19
261
Comparative phonetic vowel analysis
Table VI t-values computed for the mean vowel duration of Dutch and Utrecht men, and for the mean vowel duration of Dutch and Utrecht women
[u] [o] [:>] [a] [a] [ti] [6] [;J] [i] [I]
[e] [E]
in in in in in in in in in in in in
hoed poot hok tak haak muur neus put tien kip een hek
Men Dutch and Utrecht t (duration)
Women Dutch and Utrecht t (duration)
4·79 1-81
2·39 2·47 1·34 1·44 1·50 2·20 3·29 1·66 1·05 1·14 1·50 1·25
References Berg, J. W. van den (1953). Physica van de Stemvorming, met Toepassingen ("Physics of voice production, including applications"). Diss. 's-Gravenhage. Dale, van (1961). Groot Woordenboek der Neder/andse Taal ("Comprehensive Dictionary of the Dutch Language"). 8th ed., 's-Gravenhage. Hellwag, C. F . (1781). De Formatione Loque/ae. Diss. Tiibingen. (A photostat stencilled edition was published, with a Dutch translation, as publication 10 of the Institute of Phonetic Sciences at Amsterdam.) Koopmans-van Beinum, F . J. (1969). Nog meer fonetische zekerheden ("More Phonetic Certainties"). De Nieuwe Taalgids 62, 245-250. Koopmans-van Beinum, F. J. (1970). Vergelijkend klinkeronderzoek: Utrechts tegenover Nederlands ("Comparative vowel analyses: Utrecht dialect opposite Dutch"). Part I. Amsterdam, publication 26 of the Institute of Phonetic Sciences. Mol, H . (1963). Uit de mond der kinderen . ... . ("From the Mouth of Babes ... . ."). Logopedie en Foniatrie 9, 113-118. Tasaki, I . (1954). Nerve impulses in individual auditory nerve fibres of guinea pig. Journal of Neurophysiology 17, 97-122. Veen, T. van (1966). Het Utrechts als overgangsdialect ("Utrecht as Transitional Dialect"). Bijdragen en Mededelingen der Dialecten Commissie van de Koninklijke Nederlandse Akademie van Wetenschappen te Amsterdam 31, 5-19.
Comparative phonetic vowel analysis F. J. Koopmans-van Beinum Institute of Phonetic Sciences, University of Amsterdam Received 13th October 1972
Abstract:
This paper aims at providing a contribution to the drafting of a method of comparing the speech of a certain place or district with the speech common to the country in a significant way, making use of means and possibilities which are at the service of modern experimental phonetics. In order to obtain some concrete material a Dutch dialect, viz. the dialect of the province of Utrecht, was compared in certain aspects with non-regional Dutch. The formant frequencies and the duration of the 12 vowels of statistical data processing. It was evident that the formant values of two groups of speakers were measured and compared on the basis of the vowels alone were enough to make a distinction possible between the Utrecht dialect and non-regional Dutch and that, where necessary, duration and formant frequencies appeared to supplement one another.
Introduction
In 1966 the contents of two papers read to the Dialecten Commissie of the Koninklijke Nederlandse Akademie van Wetenschappen appeared in print entitled Utrechts, as well as the discussion which resulted from both lectures. One of them was written by T. van Veen (1966: Utrecht as Transitional Dialect). Some four assertions by van Veen were the immediate cause of the investigation described below. As characteristic phenomena of the dialect of Utrecht he mentions among other things: " ... the rather more open pronunciation of the oo, especially before a dental as in sloat, schoal, oalie, !waning. In standard pronunciation of Dutch we hear this sound before r: voor, boor. Sometimes this oo sounds slightly diphthongized" (approximately the vowel of English Maud); " ... the rather more closed pronunciation of the ee, especially before dentals: steen, been, geen. In standard Dutch this pronunciation is common before r: beer. This ee too is often slightly diphthongized .. ." (approximately the diphthong of Scottish Ian); " ... drawing out of the short ii especially before n +dental: !wand, braand, kaant. Gelderland, Brabant and the provinces lying in the eastern part of the Netherlands have this lengthening too. Short ii is also lengthened before other consonant combinations ... ;" " ... the rounded pronunciation of aa as ao in originally long aa (schaop) as well as in the in open syllable lengthened ii (waoter ) .... " Without discussing either these characteristics or the terminology, a clear resemblance can be shown to exist between these assertions, to wit in the first two phenomena explicitly and in the second two phenomena implicitly a comparison is made with vowels of standard Dutch. Van Veen does not give the impression of having done experimental phonetic investigations prior to his paper, although he suggests a comparison of Utrecht with standard Dutch vowels. I am of the opinion, however, that, if a Dutch dialect is compared
250
F. J. Koopmans- van Beinum
in a significant way with non-regional Dutch, a method has to be developed so that, where possible, use is made of modern apparatus and advanced data processing techniques for all aspects of this dialect as well as for Dutch which are of importance for such a comparison. (The term "Dutch" will from now on be used to denote "Dutch without regional characteristics"). Research Problem
In an investigation aimed at comparing vowels, attention will have to be paid to a number of characteristics of vowel phonemes relative to the language areas involved such as, for instance, formant frequencies, duration, intonation phenomena, or whatever else is thought to play a part. A further point of investigation would have to be to see if vowels in connected speech differ and, if so, in what respect they do so from vowels pronounced separately. As a simultaneous enquiry into all these aspects would be too comprehensive, attention was focused in the first instance on the formant frequencies and the duration of the vowels in disconnected words, particularly since these are the two aspects which were raised by van Veen , even if in slightly different wording. Phoneticians are generally agreed that vowels can be described in terms of formants (F1 and F 2 ). As regards the content of the notion "formant" there is, however, some difference of opinion. A formant is defined either as a resonance frequency, or as a maximum in the spectrum and therefore as a whole multiple of the basic frequency of the vocal cords, or as the natural frequency of a free resonance of the vocal tract. The measuring apparatus to be used depends on the definition chosen. lf the first is chosen then measuring is only possible after resorting to surgical intervention (cf. van den Berg, 1953). For the second definition, use is made of a filter spectrograph with which a spectrum is made and the relative maxima are measured. It is unlikely that the ear operates in the same way as a filter spectrograph. The third definition of the formant conforms with the way in which the vocal tract is brought into vibration by the pulses of the vocal cords and moreover this definition tallies with the possibilities of the ear as demonstrated by the measurements of Tasaki (1954). This definition (the frequency of a damped natural frequency of the vocal tract) was selected for this investigation. One of the consequences of this choice is that measurements have to be taken directly from a sound curve and that making use of a spectrograph does not suffice. The only information to be gained by the use of a spectrograph is the area in which the formants are situated. lf one bears in mind that the basic frequency of the female voice lies around 250Hz and that therefore with this measuring technique multiples of 250 Hz formants only can occur, it becomes clear without too much calculating that mistakes of 125Hz are by no means unlikely. As some vowels have F 1 or F2 values which are separated from contrasting vowels by barely 100 Hz, it will become clear that for a comparison of vowels of a dialect with those of Dutch and for locating shifts in the formant field spectral measurements yield information of too limited a nature. Method of Data Collecting
As for a significant comparison the groups of speakers have to be as homogeneous as possible, this investigation of the Utrecht dialect confined itself to the dialect of the villages Maarssen and Breukelen, and, for Dutch, non-regional speakers were selected.
251
Comparative phonetic vowel analysis
Three years ago a preliminary investigation was carried out for which 12 vowels of ten male and ten female students of a secondary school from Maarssen were measured as regards their formant frequencies. On the basis of statistical evidence these were compared in respect of formant frequencies to the corresponding vowels of a non-regional speech group of Dutch, consisting often male and ten female university students from Amsterdam. At this point it should be mentioned that standard Dutch has 12 monophthongs and three diphthongs. The results of this inquiry (Koopmans, 1970) appeared to merit further investigation with new groups of speakers. Utrecht In cooperation with D. Dekker and J. Compaan, both teachers from Maarssen, taperecordings were made of ten men and ten women between the ages of 25 and 65 years, all born and brought up in Maarssen or Breukelen. In order to prevent the influence which a written text might exert, pictures were used of those items which contained the desired vowel (according to a consonant-vowel-consonant pattern or a vowel-consonant pattern). The necessity of making pictures somewhat confined the choice of the key-words. The words were chosen on the advice of J. Daan, head of the Institute of Dialectology in Amsterdam, while the pictures were designed especially for this investigation by W. A. van Herpt. The tape-recordings were made with a portable tape-recorder (Nagra III, model NTPO, with a Sennheiser microphone, type MD 31 HN) and magnetic tape (Scotch low-print); speed 19 cmfs. The subjects of the experiment were orally instructed to name the objects which they were shown. In order to familiarize the speakers with the procedure the whole sequence of pictures was gone through once beforehand, whereby care was taken that the leaders of the experiment did not themselves name the objects. A phonetic notation plus pertaining key-words follows, as used in this report from now on:
[u] in [o] in [;, l in [a]
Ill
[a] in [ii l
Ill
[oJ
Ill
[d] Ill [i] Ill [I] in [e] in [E] in
hoed poot hok tak haak muur neus put tien kip een hek
(approximately the vowel of English (approximately the vowel of French (approximately the vowel of English (approximately the vowel of French (approximately the vowel of French (approximately the vowel of French (approximately the vowel of French (approximately the schwa of English (approximately the vowel of French (approximately the vowel of English (approximately the vowel of French (approximately the vowel of English
book ) beau ) hot ) las ) grave) mur ) peu ) amber) ) si lip ) ne ) set )
Dutch For the preliminary investigation (see above) as regards data collecting for Dutch, use was made of material already available at the Institute of Phonetic Sciences. However, the method of data collecting differed greatly from that used for getting the Utrecht material. Therefore recordings were made for the present investigation of a new standard group for Dutch and here, too, use was made of the same material and with the same instructions as described in the preceding paragraph for the Utrecht group. The only point of difference
252
F. J. Koopmans-van Beinum
that should be mentioned is that the Dutch recordings were made at the Institute of Phonetic Sciences with an Ampex tape-recorder (type 300) and a Philips microphone (type EL 6031/00). The problems connected with the composition of the standard group will be dealt with below. Measuring of Utrecht and Dutch material Copies were made of the recordings described above which were rendered on a tape-player with rotating play-back head (developed at the Institute of Phonetic Sciences at Amsterdam) in order to measure formants (F1 and F 2 ) and duration of the vowels. One of the possibilities of this apparatus is an unlimited repetition of a very small, carefully chosen segment of the recorded signal. This meant that for the present investigation it was possible to "lift" the vowel under scrutiny out of its consonant surroundings, so that the sound curve of this vowel segment alone could be made visible on the screen of an oscilloscope. For this purpose a storage-oscilloscope was used (Tectronix, type RM 564 with an amplifier, type 3A72 and a time-base, type 3B3), which stores the sound curve on a phosphorescent screen, so that measurements can be taken directly from the screen. The starting-point, viz. the fact that a sound curve of a vowel is composed of natural frequencies (F1 and F 2 ) superimposed on one another, suggested a method of formant measurement from the distribution of zero-crossings. The duration was measured in ms; the beginning of the vowel was chosen at the point where the formant pattern was clearly visible for the first time and the end was taken to be that point where the pertaining pattern disappeared. = - f'--1 (\ 1\ "'QV\j\.JV" L',
C\ <'>
II
0=
/'VVJ
v
(\~ \Jv
M f\-1\t[\~AD-=~ \JW V
-h·
~v
i~J
~ F
Figure 1
1
F,
Three parts of the sound curve [a] in tak pronounced by one of the Utrecht informants taken from the oscilloscope. The third curve shows the zerocrossings of F1 and Fz.
Material Processing The IBM 1130 computer of the Institute of Phonetic Sciences was used for the complicated processing of the data. The special character of the problem posed made an increase of the program library necessary. The statistical programs were written by the author of this report, the plot-programs by Ir J. G. Blom; programs were Basic Fortran IV.
Comparative phonetic vowel analysis
253
Input and processing For each speaker of Utrecht as well as for Dutch the values of F 1 and F2 and the duration of the 12 vowels were punched on cards. After this the following processing took place. Separate computation of mean values and standard deviations of F 1 and F 2 and of duration/vowel were carried out for the Utrecht groups of men and of women as well as for the Dutch groups of men and of women. The results are shown in Tables I, II, III and IV respectively. The reason the data for men and for women were processed separately is the fact that the formants of speakers with conforming articulatory configuration are inversely proportional to the length of the vocal tract (cf. Mol, 1963). In Fig. 2 the average formant frequencies for the four groups have been plotted in form ant fields. F2 0 0 <.D I
0 0
OJ I
Q
0 0
~
0 0 ~
Q2
I
I
I
I
I
3oo r-4o or--
"•
0
0 0 ~
0 0
0 0
8N I
oe
600 r-
'•
N I
0 0 <.0 N I
(Hz)
8<.D
0 0
0 0
Q
ro
0 0 ~
0 0
S!
0 0
0
0 0
8N
'!2
0 0
N N
0 0
0 0 <.D
" N
N
ei •I
'• ii e
ei
i.i e
ue
ec
•I
oe oe Je
e !:
ae
?OO r-
"
N N I
. n.
5o o r--
0 0
0 0
"•
oe
••
ee
••
00
800 rMean formant va lues of the Utrecht group of moles
900 r-
Mean forman t va lues of the Utrecht group of females
g "--
I
300 r400 r5oo r-600 700
I
u.
ue
,.
ile ;~e
oe
el
.
•e
,
ue ae
800 900
Figure 2
I
I
I
I
I
I
I
I
~·
.o
I
I
I
ei
Mean formant values of the Dutch group of moles
i.ie
ue oe
.
,
oe
ie el
ee
••
•• Mean formant values of the Dutch group of females
Mean formant values for the four groups plotted in formant fields.
Computation of the correlation coefficients of F 1 and F 2 of the 12 vowels for the four groups mentioned above (cf. Tables I, II, III and IV), and plotting of the distribution of the vowels was carried out. The ellipses indicate the areas embracing 50% of the realizations if a normal bi-variate distribution is assumed. Figure 3 shows the ellipses for the Utrecht group of males (shaded) and for the Dutch group of males (not shaded), Fig. 4 gives the ellipses for the Utrecht group of females (shaded) and the Dutch group of females (not shaded). The vowel symbols in the ellipses signify the vowels as pronounced in the given key-words. Comparison of the mean values of F 1 and F 2 for the various groups (Dutch and Utrecht) with the aid of the Student's t test (cf. Table V). At the significance level of 5% and with 18 d. f. we get t = 2·10. This implies that where values have been found fort > 2·10 we are dealing with a 5% probability level that deviations are due to chance. Significant values of t for 5% P-values have been underlined. At a significance level of 10% and with 18 d.f. we get t = 1·73. Significant values of t for 10% P-values have been underlined with a dotted line.
F. J. Koopmans-van Beinum
254
F 2 (Hz) 0
0
0 0
0
8
tl)
(\j
tl)
r:::
lQ
0
8
(\j
(\j
8
0
§
(\j
r
iC
tl)
300
Q)
®
400
~
500
:I! lC
600
\~
700
800
900
Ellipses of the formant areas embracing 50 % of the realizations assuming a normal bi-variate distribution. ll!tl, Men Utrecht; D, Men Dutch.
Figure 3
0
tl)
1'-
§
0 tl)
~
8 tl)
0
0
@
(\j (\j
0
tl)
8 tl)
(\j
300
400
500
I' [,__-
600
700
Figure 4
Ell ipses of the formant areas embracing 50% of the realizations ass uming a norma l bi-variate distribution .ll!tl, Women Utrecht; D, Women Dutch.
255
Comparative phonetic vowel analysis
A negative sign before the t-values shows that the mean formant frequency of the Dutch value is smaller than the mean Utrecht value. It should be borne in mind, however, when considering the table that a formant is one aspect of the vowel only and that each vowel is always part of a whole vowel system. Comparison of the mean values of the duration of the various groups (Dutch and Utrecht) with the aid of the Student's t test, in the same manner as described above (see Table VI). Significant values oft for 5% P-values have been underlined in the table, for 10 % P-values they have been underlined with a dotted line. A negative sign shows that the average duration for the Utrecht group is greater than for the Dutch group. A graph shows the duration of the vowels. The computed mean values for the duration of the vowels as pronounced in the given key-words, were illustrated for both groups of males and those of females (Figs 5 and 6).
280 270 260 250 240 r230f22012101200 1-
"' E
19o r1801I 701160 150 140 130 120 110 100 90 I
{)
Figure 5
e
I a
I
!
I
I
I
{l
u
1
u
='
:t
1.
u
I
Mean values of the vowel duration in the given key-words. - -, Men Dutch; - - - -, Men Utrecht.
Results and Conclusions
Results All results are summarized in tables, figures and appendices. The appendices (drawings used for the test, data concerning speakers, values measured/speaker, computer programs) are all to be found at the Institute of Phonetic Sciences ofthe University of Amsterdam. Conclusions When drawing conclusions from the above described results it should be realized clearly, that notwithstanding the approximately 1500 measurements, the material is rather limited. After all, for each vowel only one key-word of each speaker was recorded.
F. J. Koopmans-van Beinum
256
240 230
\;\ . \
e
I
\
\
220
~~,
I
~
I \
I
2 10
• I
200
"' E
.
I
\
I
I
I
190
I I
ISO
I I
170
~I\•
160
/.\
150
I
I
140
............,
130
\
120 110
·-·-..--•\ .... .
'·-------
\ \
•
100 90 i: i
Figure 6
c:
~~
o
U
i
u
,"'l
.1
1:
u
I
Mean values of the vowel duration in the given key-words. - - -, Women Dutch;-- - -,Women Utrecht.
The results that have been found are therefore always linked to key-words, that is to say to certain consonant surroundings of the vowel. This is not a serious disadvantage for formant measurements, as the influence of the bordering consonants on the rather constant middle section of the vowel is small in words pronounced in isolation. Even in the case of a vowel followed by [r] no particular deviations occur (see Koopmans, 1969). The duration of the vowels is probably influenced much more by the consonants. As long as an investigation (still in a preparatory stage) has not been completed, the conclusions that can be drawn will have to be taken to pertain only to the vowels in the key-words, as used here. Another consideration should be that the vowels have been indicated with phonetic symbols, but this is meant to signify only vowels as pronounced in these keywords. Tables I, II, III and IV record the mean values/vowel and the standard deviations of F 1 and F 2 and the duration as well as the correlation coefficients between F 1 and F 2 (necessary for the drawing of the ellipses) for the four groups of speakers. A large standard deviation for a certain vowel points to the fact that the speakers of a group differed rather a lot in their pronunciation of the vowel. In Fig. 2 the mean formant frequencies/group were set out in formant fields. The system of axes has been chosen, as is usual in the case, so that the vowel triangles that are formed correspond with the vowel triangle as given by Hell wag (1781). The following can be concluded as regards the vowel triangles in Fig. 2: (a) The same vowel triangles are found, roughly speaking, for speakers of Utrecht as for the Dutch speaking group. This points to the fact that both groups use their articulatory organs in almost the same way. Something that is not to be wondered at. (b) The Dutch speaking group has vowel triangles which are larger than those o(Utrecht
Comparative phonetic vowel analysis
257
speakers. This points to the fact that the Dutch group makes larger contrasts between the various vowels. (c) For.the Utrecht speaking group the vowel of tak lies more in the direction of Dutch [~>]in hek in the formant field than this is the case for the Dutch speaking group. Whether · this phenomenon can be called "palatalizing" is still questionable as no investigation was made here as to the place of articulation and the articulatory movements. Besides, it is a well-known fact that, with totally different articulatory positions, [~>] especially can be realized with identical formant frequencies (cf. Mol, 1966). (d) For the Utrecht group the vowel in haak has, as regards the average formant frequencies, practically the same position as the vowel in tak for the Dutch group. (e) For Utrecht speakers the first formant of the vowel in neus and the one in een have considerably higher values than for Dutch speakers. The cause is the marked diphthongization of the Utrecht pronunciation of these vowels. The Dutch group shows a shift of the first formant only at the end of the vowel, whereas the Utrecht group has a greater formant-shift during the whole of the vowel signal. This last statement demonstrates a weakness of the method described in this report. This processing method is based on the fact that Dutch vowels are, generally speaking, rather constant so far as their formants are concerned. One measurement taken from the middle of the vowel signal can be regarded as being representative of the whole vowel signal. Thus it becomes possible to set out the vowel phonemes in a two-dimensional formant field. But in the case of diphthongs and strongly diphthongized vowels measurements should be taken in quite a number of places in the vowel signal, and both formant-shifts and the speed of shifting in relation to the total duration should be taken into account in the actual processing as well as in the illustrations. The complications resulting from such an approach would be so many that it was decided, for those vowels that were strongly diphthongized, to process one measurement only, viz. from the middle of the vowel signal. It should be borne in mind when considering the results that the vowels of neus and een for the Utrecht group and the vowel of poot for most members of this group showed considerable first formant shift and that formant frequencies indicated represent in fact one moment in the middle of the shift. In Figs 3 and 4 ellipses have been drawn for male and female speakers respectively, embracing 50 % of the realizations based on a normal bi-variate distribution. As the ellipses are drawn round the mean formant frequencies the same conclusions are valid as for Fig. 2. For 3 and 4 the following must be added. (a) The ellipses for Utrecht speakers are generally speaking larger than those for the Dutch speaker group. The greater range can be accounted for by and large, by the diphthongization mentioned above. (b) For the Dutch group the vowels [o] in pool and[<>] in hok together, [o] in neus and [;}]in put together, [e] in een and [1] in kip together, and for female speakers [a] in haak and [a] in tak together show an amount of overlap, which is cancelled, however, as will be shown later by differences in duration. (c) The Utrecht group of male speakers show hardly any overlap, in the corresponding group of female speakers, conforming slightly more to the Dutch speaking group, there is overlap for the vowel of poot with that of hok, the vowel of haak with that of tak, and the vowel ofneus with that of put. Here, too, the differences in duration have a compensating influence. Table V shows the computed t-values for men and for women for the mean values of the first and second formants. The signficant values given there confirm the conclusions drawn above. 15
258
F. J. Koopmans-van Beinum
Table VI shows the computed t-values for men and for women for the duration of the vowels. In Figs 5 and 6 the mean values have been pictured. We can draw the following conclusions. (a) The average duration of the vowels for Dutch speakers is greater than for Utrecht speakers. It is possible, here too, just as for conclusion (b) above, that the cause is the more careful articulation of the Dutch group. (b) The average duration is greater for women than for men. (c) A division can be made for all four groups between longer vowels ([6], [a], [e], [o]), and shorter ones([;}], [;,],[~::],[a], [r]), with in between [ii], [i] and [u]. But for the Utrecht speaking men the vowel in hoed [u] joins the shorter vowels, as do the ones for Utrecht speaking women in hoed [u] and tien [i] . For reasons stated above (material being of too scanty a nature) it seems unjustified to draw further specific conclusions as regards absolute duration of separate vowels and their t-values. (d) There is no reason to talk of "lengthening" of the [a] in the Utrecht dialect as was done by van Veen (cf. Introduction). (e) If one considers Fig. 5 in conjunction with Figs 3 and 4 the following conclusion can be drawn. For Dutch as well as for Utrecht speaking groups, for those cases where two vowels overlap in the formant field these vowels are far removed from in the duration graph (cf. [r] and [e]; [;}]and [o]; [;,]and [o] ; [a] and [a] in Dutch), suggesting that duration and formant frequencies complement one another where necessary. Discussion
The investigation described above is an attempt at comparison, at least for certain aspects, of speech sounds of a dialect with the standard pronunciation. The term dialect is defined as follows by van Dale (1961): (1) "the special speech of an area or of a place in so far as it differs from the general speech or from that of the country", and (2) as being: "each of those languages which originate from a common parent language" . The first definition reflects a synchronic, the second a diachronic approach, but in either definition the relation to the general speech or to the parent language is referred to. It will be clear that for a comparative phonetic investigation of speech sounds only the first meaning is of importance as a rule. Unless, of course, a comparison between two dialects is wanted based on their common parent language which itself is more likely to exist only in written form. For Dutch and its dialects the synchronic approach will, as a rule, be of most interest to the phonetician, which means that the relation of a contemporary Dutch dialect will have to be compared with present-day standard Dutch. Norm-group
There will, generally speaking, be no difficulties when forming a group of dialect speakers, as the dialect under investigation is by definition determined by the area or the place. Forming a norm-group for standard Dutch poses a far greater problem. How should such a group be composed or who composes this group, for it can not be denied that the "how" depends on the "who"? One possible way to circumvent this is to take a representative sample of the population of Dutch adults. The private opinion of every judge is kept out of consideration. This is, however, a rather unsatisfactory procedure, as a kind of "average Dutch" can be determined in this way, but it is unlikely that any person can be found who, in fact, speaks this "average Dutch" .
Comparative phonetic vowel analysis
259
If the judgment of one or some people is taken into account, the composition of a normgroup becomes an extremely arbitrary affair. This procedure was, however, used in this investigation as no suitable alternative method exists. A third, possibly the only acceptable, alternative is to do justice to the opinion of as many judges as possible. This involves an mvestigation of the manner in which the judgments were made. Also the matter should be gone into in how far one can possibly form a norm-group of speakers on the basis of judgment criteria. An extensive investigation is in progress at the Institute of Phonetic Sciences concerning these problems. The Follow-up It would be desirable to repeat the investigation as described above with large groups of speakers and with a great number of key-words. To what extent speech sounds in connected speech differ from those in separately pronounced words is a further point to be gone into. At the moment the measuring, as such, involves so much labour, that this can be done extensively only when the measuring process has become automated. Table I Men Utrecht. Mean values and standard deviations of Fl> F 2 and of duration; correlation coefficients of F 1 and F 2
Mean F 1 (Hz) [u]
[o] [;,] [a]
in in In
in
[a]
In
[U]
in
[oJ
In
[;)]
In
[i]
in
[I)
m
[e)
in
[c]
In
hoed poot hok tak haak muur neus put tien kip een hek
389 497 577 682 690 359551 468 336 403 492 610
F,
Mean Fz
(Hz)
(Hz)
F2 (Hz)
31 35 49 73 82 39 72 52 30 37 76 103
818 976 977 1451 1197 1874 1688 1698 2276 2199 2076 1934
82 93 86 109 142 150 143 193 174 182 144 175
S. D.
S.D .
Cor. coeff. - 0·034 0·615 0·612 0·513 0·721 0·045 0·386 0·100 - 0·068 0·148 - 0·085 - 0·138
Mean dur.
S. D.
(ms)
(ms)
107 186 116 105 214 168 208 106 147 96 195 99
19 16 18 21 34 30 24 16 25 17 16 19
Table II Women Utrecht. Mean values and standard deviations ofF,, F 2 and of duration; correlation coefficients of F 1 and F 2
Mean F 1 (Hz) [u]
m
[o]
In
[;,] [a]
[oJ
in in in in in
[;)]
In
[i]
In
[a] [U]
[I)
In
[e)
lil
[c]
in
hoed poot hok tak haak muur neus put tien kip een hek
419 597 653 758 722 393 562 497 394 450 550 693
F1 (Hz)
S.D.
33 66 102 79 111 39 75 63 28 37 66 73
Mean Fz (Hz)
Fz (Hz)
869 1030 1126 1462 1303 1919 1965 1977 2646 2540 2407 2216
79 144 116 141 164 143 58 81 58 74 108 159
S.D.
Cor. coeff. 0·395 0-413 0·082 0·741 0·494 0·257 - 0·241 0·544 - 0·543 - 0·134 - 0·021 - 0·017
Mean dur.
S.D.
(ms)
(ms)
133 207 119 124 244 170 232
33 33 33 24 37 42 29 27 30 28 45 32
118
139 112 215 120
260
F. J. Koopmans-van Beinum Table III Men Dutch. Mean values and standard deviations of Fh F2 and of duration; correlation coefficients of F1 and F2
Mean F1
Fl (Hz)
S.D.
(Hz)
[u] [o] [:>] [a]
[a] [i.i]
[o] [;J]
[i] [I] [e] [e]
in in m
in in in in in in in in in
hoed poot hok tak haak muur neus put tien kip een hek
25 44 67 33 39 31 55 30 25 22 37 39
334 464 538 639 738 308 406 436 306 374 403 618
Mean Fz (Hz)
F2 (Hz)
813 899 928 1292 1409 1819 1650 1596 2494 2196 2218 1877
71 85 94 86 77 138 83 116 126 115 130 98
Mean dur. S.D. (ms) (ms)
S.D.
Cor. coeff.
0·380 0·635 0·537 0·254 0·069 - 0·359 0·088 -0·022 - 0·414 - 0·615 -0·402 0·201
141 206 124 111 211 191 224 125 148 104 215 117
9 29 22 21 42 40 41 13 30 16 44 20
Table IV Women Dutch. Mean values and standard deviations of F1 , F2 and of duration; correlation coefficients of F1 and F2
[u] [o] [:>] [a]
[a] [i.i]
[o] [;J]
[i] [I] [e] [e]
in in in in in in in in in in in m
hoed poot hok tak haak muur neus put lien kip een hek
Mean F 1
S.D. Fl
Mean F2
(Hz)
(Hz)
(Hz)
F2 (Hz)
403 505 605 757 855 371 495 488 376 448 475 753
20 59 83 65 79 32 67 38 29 47 43 52
851 926 995 1277 1439 2064 1914 1788 2734 2594 2527 2231
69 61 86 137 128 158 135 90 139 103 114 172
S.D.
Cor. coeff.
Mean dur. (ms)
(ms)
168 248 137 .138 267 216 283 138 155 125 244 135
29 36 20 15 27 46 36 25 34 19 38 18
-0·239 0·745 0·501 0·671 0·441 - 0·314 -0·269 -0·080 0·234 0·312 0·622 0·283
S.D.
Table V t-values computed for the mean vowel formants of Dutch and Utrecht men, and for the mean vowel formants of Dutch and Utrecht women
Men Dutch and Utrecht t (Ft) t (Fz) [u] [o] [:>] [a]
[a] [i.i]
[o] [;J]
[i] [I] [e] [e]
in in in in in in in in in m
in in
hoed pool hok tak haak muur neus put tien kip een hek
-4·19 -1·73 -1·38 -1-61 1·55 -3·06 -4·82 -1·62 -2·27 -2·03 - 3·13 0·21
-0·13 -1·82
_.j:J.s
-3-41 3·93 -0·80 -0·69 -1·35 3·03 -0·03 -2·32 -0·85
Women Dutch and Utrecht t (F1) t (F2)
-1·25 -3·12 -1 ·10 -0·02 -2·93 -1·33 -1·98 _(j:j()
-1·28 -0·09 -2·86 1·99
-0·51 -1·99 - 2·70 -2-81 1·95 1-04 -1·04 - 4·68 1·74 1·29 2·29 0·19
261
Comparative phonetic vowel analysis
Table VI t-values computed for the mean vowel duration of Dutch and Utrecht men, and for the mean vowel duration of Dutch and Utrecht women
[u] [o] [:>] [a] [a] [ti] [6] [;J] [i] [I]
[e] [E]
in in in in in in in in in in in in
hoed poot hok tak haak muur neus put tien kip een hek
Men Dutch and Utrecht t (duration)
Women Dutch and Utrecht t (duration)
4·79 1-81
2·39 2·47 1·34 1·44 1·50 2·20 3·29 1·66 1·05 1·14 1·50 1·25
References Berg, J. W. van den (1953). Physica van de Stemvorming, met Toepassingen ("Physics of voice production, including applications"). Diss. 's-Gravenhage. Dale, van (1961). Groot Woordenboek der Neder/andse Taal ("Comprehensive Dictionary of the Dutch Language"). 8th ed., 's-Gravenhage. Hellwag, C. F . (1781). De Formatione Loque/ae. Diss. Tiibingen. (A photostat stencilled edition was published, with a Dutch translation, as publication 10 of the Institute of Phonetic Sciences at Amsterdam.) Koopmans-van Beinum, F . J. (1969). Nog meer fonetische zekerheden ("More Phonetic Certainties"). De Nieuwe Taalgids 62, 245-250. Koopmans-van Beinum, F. J. (1970). Vergelijkend klinkeronderzoek: Utrechts tegenover Nederlands ("Comparative vowel analyses: Utrecht dialect opposite Dutch"). Part I. Amsterdam, publication 26 of the Institute of Phonetic Sciences. Mol, H . (1963). Uit de mond der kinderen . ... . ("From the Mouth of Babes ... . ."). Logopedie en Foniatrie 9, 113-118. Tasaki, I . (1954). Nerve impulses in individual auditory nerve fibres of guinea pig. Journal of Neurophysiology 17, 97-122. Veen, T. van (1966). Het Utrechts als overgangsdialect ("Utrecht as Transitional Dialect"). Bijdragen en Mededelingen der Dialecten Commissie van de Koninklijke Nederlandse Akademie van Wetenschappen te Amsterdam 31, 5-19.