The English Vowel Space of Filipino Children
Christine C. Espedido
Department of Linguistics, University of the Philippines, Diliman
tintin7978@hotmail.com
ABSTRACT
This paper describes the acoustic characteristics of English
vowels, as spoken by Filipino elementary school students.
Acoustic measures of duration and first and second formant
frequencies were obtained from 30 children, while producing
words containing the vowels /i, ɪ, e, ɛ, æ, a, ɔ, o, ʊ, u, ʌ/ in
English, representing both genders. In characterizing these
vowels, I also compared the data to a vowel mapping of the
Filipino vowels of the children and to the vowels of 46
American children from the data of Hillenbrand et al., [J.
Acoust. Soc. Am., 97, 3099-3110 (1995)]. The analysis of this
study is that Filipino children could produce or 6 out of the 11
English vowels. The Philippine English vowels are /a/, /e/, /ɛ/,
/i/, /ɔ/ and a near-close near back rounded /u/. Moreover,
Filipino English vowels were 62% shorter than that of the
American L1 speakers. This paper is a first approximation of
the sounds of Philippine English as spoken in the elementary
grades in a particular public school and explores how and why
they differ from the sounds that native English speakers
produce.
Keywords:
vowel space, acoustic phonetics, Filipino-
English.
1. INTRODUCTION
1.1. Background
Any L1 or L2 teacher in any multilingual country must be able
to have a good grasp of the learner’s first language and the
target language to become an effective language teacher. A
good knowledge of acoustic phonetics can also help in this
regard. Knowledge of the acoustic cues accompanying speech
production of the source and target language and a sense of
where the learners are, can prepare the language teacher better
for his or her work of facilitating the transfer of L1 skills to the
L2. In this paper, a representative vowel inventory of English as
spoken by Filipino children will be presented. I will address the
problem of mapping the English vowels to the Filipino vowels
of the children. To describe further, the data will be compared to
the vowels of 46 American children.
1.2 Previous studies
English is a global language and it is essential for
communication. However, the status of the English language in
the world today is different from what it used to be. It is a
property of the world and does not belong to native-speakers
alone but to all speakers of English worldwide. Philippine
English is a variety of English used in the Philippines by the
media and the vast majority of educated Filipinos. Philippine
English exists and it is a legitimate variety of English, that is
developing its own standards. For global competitiveness,
English proficiency is needed. Does the “Global Filipino” still
have an edge with Philippine English?
To answer this question, we need to scrutinize the status of
Philippine English. Bautista [1] made an inventory of deviations
in the sentences in a corpus and focused on grammatical features
which now have become acceptable and part of the standard
Philippine grammar. The analysis identified deviations in
subject-verb agreement, in the use of articles, prepositions,
tenses, mass nouns and count nouns, and in pronoun-antecedent
agreement. With regards to pronunciation, she states that
“Philippine English has not been stabilized and it still
constitutes a multiplicity of idiolectal pronunciations that do not
make up a distinct standard variety.”
As Gonzales [2] tried to determine the features of the spoken
and written English by educated Filipinos over the years, he had
found that there has been a diminution of achievement among
today’s generation of learners.
These works of Bautista and Gonzales reflect on many other
studies, capitalizing on performance slip and acquisitional
deficiency of the Philippine English. They call for innovations
in methodology and competence in teachers.
Works done by Martinez [3] and Mata and Soriano [4] deal with
raising the standards in the teaching of English in the
Philippines. Martinez used an approach of using Filipino models
instead of American models or the “integrative approach” in
teaching English pronunciation with the use of drills and
exercises. Martinez states that the Tagalog speaker will have no
difficulty with the vowels /i, e, a, o, u/ of what she calls
Standard Filipino English since these are found in his language.
But, that speaker will experience difficulty with /, æ, ə, ʊ, and
ɔ/. The English vowel / ɪ / is usually replaced by the Tagalog /i/
or /e/, / æ / with /e/ or /a/, / ʊ/ with /u/, / ɔ/ by /o/ and / ə/ by
Tagalog /a, e, i, o, u/. For Martinez, the Tagalog vowel
phonemes in her dataset are /a, e, i, o, u/ whereas the Standard
Filipino English vowel phonemes are /i, ɪ, e, æ, ə, a, u, ʊ, o, ɔ/.
2.2 Procedure
Similarly, Mata and Martinez provided drills and techniques to
improve oral English. They said that it is insufficient to just
merely hear the sound and that it will be necessary for the
student to know what to do with the lips, the tongue, and the
vocal organs; to know the length of the sound, and other
characteristics which will help him produce the sound correctly
without substituting the vernacular counterparts.
2.2.1 Data Collection
This paper agrees with the idea that the pronunciation quality
does not solely depend on the ability to produce the words
correctly; it also depends on the knowledge of how the words
should be pronounced. Here, I will be using acoustic analysis
which can show the spectral distribution and other acoustic
dimensions of sounds. The acoustic signal bridges the acts of
speech production and speech perception. Acoustic phonetics
can suggest appropriate phonological features for descriptive
use.
There is limited research done in the field of children’s speech
analysis and recognition in the Philippines. Even though
children’s language learning is highly important, it is relatively
hard to obtain effective tools for pronunciation assessment due
to the special characteristics of children’s speech and the limited
availability of children’s speech data in the speech research
community. For example, children’s speech is characterized by
higher pitch and formant frequencies in comparison with adults’
speech. Understanding the characteristics of children’s speech
can help devise strategies for testing and training speech
perception and production skills.
This paper aims to describe the acoustic characteristics of
English vowels as spoken by Filipino children. To be able to
effectively describe the vowel inventory of the target language,
it is necessary to highlight its acoustic similarities and
differences to the vowels of their mother tongue- Filipino [5].
Delos Reyes et al [6] mentioned that although orthographically
there are five vowels in Filipino, there are only four sounds at
the acoustic level. These vowel phones are “a” [a], “i",[ ɪ], “e”
[ɛ], and /Y/. Of these vowels, /a/ is the most invariant. /i/ and /e/
are two distinct sounds. ‘o’ and ‘u’ are pronounced as the nearclose near-back rounded vowel /Y/. The last sound was found
to be lower than /u/ and /i/ but higher than /o/ and /e/ based on
the IPA index.
2. METHOD
2.1 Participants
Total subjects recorded were 30 elementary school students
attending a public school in Quezon City coming from Grades 4,
5, and 6. Each subject is a member of the first section of each
grade level. Gender balancing was possible with all groups.
Each group had 5 males and 5 females. The age range of the
Grade 4 students is from 9 to 10 years old, the Grade 5 students
are from 10 to 11 and the Grade 6 students are from 11 to 12
years old.
Twelve English vowels were supposed to be analyzed, as spoken
by Filipino children and compared to the data by Hillenbrand et
al. However, the researcher found one vowel, /ɝ/ in
Hillenbrand et al’s data that seemed incomparable to any of the
sounds in the data collected in this paper. Thus the present
dataset is restricted to the vowels /i, ɪ, e, ɛ, æ, a, ɔ, o, ʊ, u, ʌ /.
Audio recordings were made of subjects reading 2 word lists.
The first word list contains 22 English monosyllabic words, 2
tokens for each of the 11 vowels of American English: /i, ɪ, e, ɛ,
æ, a, ɔ, o, ʊ, u, ʌ /, as shown in Table I. The second word list
contains 20 Filipino words, 4 tokens for each of the 5 Filipino
vowels: /a, e, i, o, u/, as shown in Table II, with stresses at
varying positions. This data set has a total of 42 tokens per
subject.
Table I. Vowel tokens for acoustic analysis – English
Vowels
Tokens
i
feet
teeth
ɪ
bit
hit
e
bait
fake
ε
bet
get
æ
cat
map
a
lock
knock
ɔ
caught
chalk
o
boat
coat
ʊ
book
pull
u
boot
cool
ʌ
but
nut
Table II. Vowel tokens for acoustic analysis – Filipino
Vowel
Tokens
“i”
ibon
itim
putik
puti
“e”
tenga
relo
balde
ate
“a”
bata
kanta
bantay
lata
“o”
bola
bodega
buntot
tito
“u”
usok
ubo
pintura
sinturon
The recordings were done in a quiet classroom at the Quirino
Elementary School. The read speech data was recorded using a
Sony IC Recorder, ICD-P520. Each utterance was recorded in
an individual .wav 16-bit sound file at a sampling rate of 44.1
kHz. Since the room where the recordings were conducted was
not sound-attenuated, the data had to undergo a noise removal
process using NCH WavePad sound Editor.
2.2.2 Data Analysis
Praat scripts were written to facilitate automatic acoustic
measurements of the data. All sound files and textgrid files were
hand-checked for accuracy. The following acoustic
measurements were made: duration of individual phonemes and
the first two formants (F1 and F2) of the vowels of interest.
Extreme outliers of formant analyses were eliminated.
2.3 RESULTS
vowels of the students from grades 4 and 5. The mean duration
of the vowels of the grade 6 students is 45 ms longer than the
mean duration of grades 4 and 5 students.
One of the goals of this paper is to try to determine if the spoken
English vowels of the Filipino children are affected by their L1
(Filipino) vowels by analyzing and comparing their acoustic
characteristics. 600 tokens of the Filipino vowels were recorded
and analyzed but only 300 of the tokens were selected for
investigation. The tokens involve the vowels, “a”, “e”, “i”, “o”,
“u”. In the analysis, it was found out that the means of the
durations of the vowels of Filipino-English (168ms) and
Filipino (166ms) vowels are just the same.
2.3.1
Duration (ms) of American and Filipino-English and Filipino vowels as spoken by Filipino
children
Vowel Duration
300
Since, vowel duration may be expected to contribute to the
perceptual identification of vowel tokens by English listeners, I
measured vowel duration in each of the 660 tokens in my data
and plotted the mean vowel duration for each of the eleven
types.
200
ms
The English vowel durations of Filipino children speakers are
shorter than that of the American L1 speakers (with differences
of means between 65-152 ms). The duration of the Filipino
children’s English vowels range between 151 to 195 ms,
compared to the range of 234-322 ms for American L1 speakers.
This means that Filipino English vowels were 62% shorter than
that of the American L1 speakers.
250
150
Series1
100
50
350
300
0
American
Filipino-English
Filipino
250
200
4
5
6
American
150
Figure 2. Average Duration (ms) of American, FilipinoEnglish and Filipino vowels as spoken by Filipino children.
Table III. Average durations of English vowels produced by
30 Filipino children and 45 American children at
Hillenbrand et al’s data.
100
50
Duration
Vowels
0
/ε/
/ʌ/
/U/
/I/
/u/
/i/
/o/
/a/
/e/
/Ɔ/
/æ/
Figure 1. Average duration (ms) of English vowels as spoken
by Grades 4, 5 and 6 Filipino and American children.
The four short vowels with short durations in American English
are / ɪ, ɛ, ʌ, ʊ/ (with means between 234-248 ms), while the
long vowels are /i, e, æ, ɔ, o, u, a/ (with means between 278322 ms). When the vowels are ordered from short to long, the
increment between adjacent vowels is not more than 19 ms
(which is the difference in mean vowel duration between /u/ and
/i/).
If we now consider the English vowel durations of the thirty
grades 4, 5 and 6 Filipino children, we notice that the vowels of
the grade 6 students are the longest as opposed to that of the
American
Filipino
i
297
160
ɪ
248
151
e
314
191
ε
235
170
æ
322
177
a
311
161
ɔ
319
167
o
310
195
ʊ
247
162
u
278
165
ʌ
234
152
Table IV. Average F1 frequencies (Hz) of English vowels
produced by 30 Filipino children and 45 American children
in Hillenbrand et al’s data.
F1
Vowels
American
Filipino
Table VII. Formant frequencies (Hz) of Filipino stressed and
unstressed vowels produced by 30 Filipino children
Vowels
F1
F2
“i"
446
2498
“e”
630
2262
i
452
471
ɪ
511
478
“a”
873
1590
e
564
500
“o”
606
1222
ε
749
668
æ
“u”
482
945
717
952
a
1002
938
ɔ
803
731
o
597
519
ʊ
568
496
u
494
487
ʌ
749
864
Table V. Average F2 frequencies (Hz) of English vowels
produced by 30 Filipino children and 45 American children
in Hillenbrand et al’s data.
2.3.2. Formant Frequencies
According to Ladefoged [7], the best way of describing vowels
is not in terms of the articulations involved, but in terms of their
acoustic properties. And the most important acoustic properties
of vowels are the formants which can be readily seen in sound
spectrograms. Therefore the first and second formant
frequencies (resonant frequencies of the vocal tract) were taken.
F1 corresponds inversely to the height dimension (high vowels
have a low F1 and low vowels have a high F1). F2 corresponds
to the advancement (front/back) dimension (front vowels have
high F2 and back vowels have low F2).
F2
Vowels
American
Filipino
i
3081
2961
ɪ
2552
2790
e
2656
2410
ε
2267
2191
æ
2501
1611
a
1688
1475
ɔ
1210
1225
o
1137
951
ʊ
1490
963
u
1345
967
ʌ
1546
1518
Table VI. Average durations (ms) of Filipino vowels
produced by 30 Filipino children
Vowels
Filipino
“i"
169
“e”
165
“a”
160
“o”
181
“u”
158
Figure 3. Average values in Hertz of F1 and F2 of American
English vowels as spoken by 46 children (Hillenbrand et al
[10]) ; “i”=/i/, “ɪ”=/ɪ/, “e”=/e/, “E”=/ɛ/, “æ”=/æ/, “a”=/a/,
“c”=/ɔ/, “o”=/o/, “”U”=/ʊ/, “u”=/u/, “ʌ”=/ ʌ/.
Figure 3 shows the mean of the F1-F2 of all the English vowels
of 46 American children in Hillenbrand et al’s data. The
distributions of measured formants in this plot, corresponds
closely to the distributions of phonetic values. However, the
values are higher compared to the vowels of adults, considering
the fact that the subjects in this particular analysis are children.
Figure 4. Average values in Hertz of F1 and F2 of English vowels as spoken by 30 Filipino grade school children “i”=/i/, “ɪ”=/ɪ/,
“e”=/e/, “E”=/ɛ/, “æ”=/æ/, “a”=/a/, “c”=/ɔ/, “o”=/o/, “”U”=/ʊ/, “u”=/u/, “ʌ”=/ ʌ/.
Figure 4 shows the mean of the F1-F2 of all the English vowels
of Filipino children. The Filipino children’s vowels show tight
clustering, and therefore little spectral distinction between
intended /u/, /ʊ/ and /o/. Similarly, there is hardly any spectral
difference between /æ/, /ʌ/ and /a/, nor between /i/ and /ɪ/. The
vowel /e/ is a mid-front unrounded vowel like the /e/ of
American English, as well as the vowels /ɛ/ and /ɔ/.
2.4 DISCUSSION
The F1/F2 formants of the vowels of American children in
Hillenbrand et al’s data are slightly higher in frequency than
those of the Grades 4, 5 and 6 Filipino children, speaking
English. Also, the American children’s vowels showed longer
durations (62%) than Filipino-English as spoken by the Filipino
children. These differences may be observed in the mean
formant frequencies and duration given on Table III.
This paper sought to determine if the Filipino (L1) vowels
affects the production of English (L2) vowels as spoken by
Filipino elementary school children. As expected, in the
Filipino-English and Filipino vowel space, considerable
overlapping of areas is indicated, particularly between [o], [],
and [u] of Filipino-English and [u]-Filipino.
The Filipino children’s English vowels show tighter clustering,
and narrower space, and therefore there is little distinction
between /i/ and /ɪ/ of Filipino-English and the “i” of Filipino.
The comparison of F1 means for the Filipino English /i/, /ɪ/, and
“i” of Filipino, using ANOVA provided evidence of a
meaningful difference [F=8.91; p<0.05]. We can say that these
three vowels have different vowel height. The Filipino-English
/i/ is slightly more back than Filipino-English /ɪ/ and Filipino
“i”. Similarly, the vowels /æ/ (which is a low front vowel in
American English), /ʌ/ (which is in the mid central position) and
/a/ are articulated in the low-back region together with the
Filipino “a’. A comparison of F1 means for the vowels /æ/ and
/a/ using student’s t test provided no evidence of difference
between the two.
from individual words. Therefore, for this study, the Filipino
vowels of the Filipino children are /a, e, i, o, and u/.
On the other hand, the Filipino-English vowels also include the
vowel /ɔ/. It is different from the Filipino vowels “o” nor “u” for
it occupies a different area in the vowel space, from Figure 7,
and from the evidence using ANOVA, [F=119.58;p<0.05]. The
Filipino-English vowels are /a/, /e/, /ɛ/, /i/, /ɔ/ and a near-close
near back rounded /u/ which is the vowel /Y/ in Delos Reyes et
al’s data.
2.5 CONCLUDING REMARKS
Figure 6. Plot of Mean Values in Hertz of F1 versus F2 of the
Filipino Vowel Space of Filipino children
With the inventory in Figure 6, we could see that the Filipino
children could produce or approximate 6 out of the 11 English
vowels. As for the other sounds, substitutions are being made by
Filipino learners of English, that could result into serious
confusion. For example, the substitution of /ɪ/ for /i/ as observed
in children’s pronunciation of the word “bit” with /bi:t/ instead
of /bɪt/, of the word “map” with /map/ instead of /mp/. Such
“errors” can be noticeable by just plain hearing it. Now that a
phonetic data analysis has provided us with the acoustic data to
differentiate there variable pronunciation in English, the next
step would necessarily be on how to view these variable
pronunciation in Philippine English. Is this a bad thing or a
good thing? This paper however is not prepared to deal with this
controversy at this time.
3. REFERENCES
[1] Bautista, L. 2000. Defining Standard Philippine English:
It’s Status and Grammatical Features. Manila, Philippines:
De La Salle University Press, Inc. p. 72-75.
[2]
Gonzales, A.. Jambalos, T., and Romero, C. 2003. Three
Studies on Philippine English across Generations: Towards
an Integration and Some Implications. Manila, Philippines:
De La Salle University Press, Inc. p. 43-44.
[3] Martinez, N. 1975. Standard Filipino English
Pronunciation. Manila, Philippines: Navotas Press.
[4] Mata, L. and Soriano, I. 1967. English Pronunciation for
the Filipino College Student: Theory, Technique and
Practice Material on Sound, Rhythm and Intonation.
Quezon City, Philippines.
Figure 7. Plot of Mean Values in Hertz of F1 versus F2 of the
Filipino vowels “o” and “u” and the English vowel /ɔ/ as
spoken by Filipino children.
With the plot of the formant frequencies of the Filipino vowels
as spoken by the Filipino children on Figure 7, this paper
contradicts the study done by Delos Reyes et al [6] that proposes
that there are only four sounds in Filipino, which are /a/,/e/,/i/
and /Y/, where “o” and “u” are pronounced as the near-close
near back rounded /Y/.
As seen in Figure 7, the Filipino vowels “o” and “u” are in
different areas in the vowel space. One explanation for the
difference may be because Delos Reyes et al’s data was taken
from a sentence reading material whereas this paper’s data came
[5] Oppelstrup, L., Blomberg, M., and Elenius, D., 2005.
Scoring Children’s Foreign Language Pronunciation. In
Proceedings of FONETIK, Department of Linguistics,
Goteborg, University. p.51
[6] Delos Reyes, J., Santiago, P.J., Tadena, D., Zubiri, L.A.
2009. Acoustic Characteristics of the Filipino Vowel
Space. In Proceedings of the 6th National Natural Language
Processing Research Symposium. De la Salle University,
Manila, Philippines.
[7] Ladefoged, P., Phonetic Data analysis: An Introduction to
Fieldwork and Instrumental Techniques. 2003. Oxford,
UK. Blackwell Publishing. p. 104-105.