TOWARDS LANGUAGE PRESERVATION:PRELIMINARY COLLECTION AND VOWEL ANALYSIS OF
INDONESIAN ETHNIC SPEECH DATA
Auliya Sani1,2 , Sakriani Sakti1 , Graham Neubig1 , Tomoki Toda1 , Adi Mulyanto2 , Satoshi Nakamura1
1

Nara Institute of Science and Technology, Japan
2
Bandung Institute of Technology, Indonesia{auliya-f,ssakti,neubig,tomoki,s-nakamura}@is.naist.jp{13509067@std,adi@}.stei.itb.ac.id

ABSTRACTMultilingualism in Indonesia gradually faces a state of catastrophe. Although several projects have been initiated for
cultural preservation, the available technology that could
support communication between elders and younger people within indigenous communities, as well as with people
outside the community, is still very rare in Indonesia. This
paper presents the first step of long-term development ofspeech-to-speech translation system from ethnic languages
to English/Indonesian, which is collection and analysis ofIndonesian ethnic speech corpora. Here, we will first focus
on the two largest ethnic groups in Indonesia: Javanese andSundanese.
Index Terms— Language preservation, Indonesian ethnic languages, speech data collection, vowel analysis

On the other hand, the global, borderless economy andinformation communication technologies have a great impact
on the way of communication. People have to be able to communicate well with others who speak different languages. As
an international language, English has become the most spoken language in the world with more than 1.8 billion speakers.
Thus, in modern Indonesia, along with the campaign of Bahasa Indonesia, English is also promoted starting at primaryeducation.
Although using a common language, such as Indonesianas official Indonesia language, or English as a world language
helps the Indonesian people to face globalization, multilingualism in Indonesia faces a state of catastrophe. Currently,of 726 languages, 146 are endangered, at risk of falling out ofuse, generally because there are few surviving speakers. If alanguage loses all of its native speakers, it becomes extinct. In
the near future, more and more languages will be endangered.

1. INTRODUCTION
Indonesia is an archipelago comprising approximately 17500
islands inhabited by hundreds of ethnic groups with morethan 237 million people (based on Census 2010)1 . The twolargest ethnic groups are Javanese and Sundanese living inJava Island. Different ethnic groups speak various different
languages. One of the bridges that binds the people together
is the usage of Bahasa Indonesia, the national language. It
is a common language formed from hundreds of languages
spoken in the Indonesian archipelago, and was coined by Indonesian nationalists in 1928. It further became a symbolof national identity during the struggle for independence in1945. Compared to most other languages, which have a highdensity of native speakers, only small proportion of Indonesia’s large population speaks Bahasa Indonesia as a mothertongue while the great majority of people speak it as a second
language with varying degrees of proficiency. To promote theusage of the Indonesian language, the government makes astrong campaign to use Indonesian in daily life.
1 Badan Pusat Statistik (Central Bureau of Statistic) – http://bps.go.id

Fig. 1. Speech translation between ethnic languages to English/Indonesian.
Several projects have been initiated for cultural preservation, which can prevent the endangered language from being lost, some examples include holding language congress,
documenting the words, making rules for public servant tospeak in ethnic languages on a given day, etc. Nevertheless,the available technology that can support communication
between elders and younger people within indigenous communities, as well as with people outside the community, is
still very rare in Indonesia. As a result, indigenous communities still face isolation due to language and culturalbarriers. Our long-term goal is to establish an infrastructure of speech-to-speech translation from ethnic languages
to English/Indonesian (See Fig. 1). This technology enables
communication between two people who speak different

languages. Therefore, speech translation technology is significant to indigenous communities in Indonesia to overcome
language barrier, cross the cultural gap, and to face globalization.
This paper presents the first step towards developing
speech technology, which is collection and analysis of Indonesian ethnic speech corpora. As preliminary study, we
start with the two largest ethnic groups in Indonesia: Javanese and Sundanese. Eventhough these languages are notyet endangered, the speakers of Javanese and Sundanese are
greatly reduced recently. In the next section, we briefly describe the overview of Javanese and Sundanese languages.
The existing Indonesian data will be described in Section
3, and the current development of Javanese and Sundanese
speech corpus will be described in Section 4. In Section 5,
the analysis of vowels in standard Indonesian, Javanese, andSundanese is presented. Finally, we draw our conclusions in
Section 6.

Fig. 3 [1]. Hanacaraka and Aksara Sunda are described inUnicode Standard Ver. 6.0.

Fig. 2. Javanese script: Carakan letters.

2. JAVANESE AND SUNDANESE LANGUAGESCHARACTERISTICS
2.1. Written Script
Although the Indonesian language is infused with highly
distinctive accents from different ethnic languages, there aremany similarities in patterns across the archipelago. Modern Indonesian is derived from Malay dialect, which was the
lingua franca of Southeast Asia. In earliest records, Malay
inscriptions are syllable-based and written in Arabic script,
however modern Indonesian is currently phonetic-based andwritten in Roman script. It uses only 26 letters as with thecase of the English/Dutch alphabet.
On the other hand, some of ethnic groups in Indonesia still
use their own transcription in daily life. The two largest ethnic groups in Indonesia, Javanese and Sundanese, are counted
in that category. Even in elementary school education, thesubject of learning this language is still given. Javanese transcription is called Aksara Hanacaraka and Sunda transcription called Aksara Sunda. Aksara means transcription in Indonesia. These transcriptions derive from Pallawa transcription from South India. Hanacaraka consists of 20 basic letters (consonants with vowel a) called Carakan, 20 letters tomake basic consonant of each Carakan letter called Pasangan,
5 vowels, transcription for numbers and for foreign words
and honorifics, as well as punctuation called Sandhangan. To
make a different syllable, Sandhangan is added to change thephoneme. Fig. 2 shows Carakan letters of Javanese script2 .
Hanacaraka is already included in Unicode (A980-A9DF).
Similar to Hanacaraka, Aksara Sunda also has basic letters,
vowels, punctuation to change phoneme, and basic punctuation. Ngalagena, basic letters in Aksara Sunda, has beenregistered in Unicode (1B80-IBBF). Ngalagena is shown in
2 The official site of Aksara Jawa – http://hanacaraka.fateback.com/

Fig. 3. Sundanese script: Ngalagena letters.

2.2. Phoneme Set
The Indonesian phoneme set consist of 10 vowels (including
diphthongs) and 22 consonants [2]. The vowels include /a/(like “a” in “father”), /i/ (like “ee” in “knee”), /u/ (like “oo” in“moon”), /e/ (like “e” in “bed”), /@/ (a schwa sound, like “e”
in “lantern”), /o/ (like “o” in “boss”), and four diphthongs,/ay/, /aw/, /oy/, and /ey/.
The Javanese and Sundanese phoneme sets are similar to
those of Indonesian. The Sundanese phoneme set contains
7 vowels and 21 consonants. Sundanese has no diphthongs,
but instead has another vowel /eu/. Sundanese also does nothave consonant /f/ and /z/. However, influenced by the use ofIndonesian, nowadays Sundanese covers these consonants aswell. But still, Sundanese does not have /kh/ and /sy/ as inIndonesian. Similar to Sundanese, the Javanese phoneme set
has no diphthongs and did not have /f/ and /z/ previously. In
addition, Javanese has /E/ and /O/ (like “a” in “saw”). In total,
the Javanese phoneme set contains 8 vowels and 23 consonants.
Unlike Indonesian and Sundanese, Javanese has manyrules in reading especially for vowels. For example, when
the letter “a” lies in the end of word, it is called an open
syllable and sometimes spoken as /O/. In the other hand, if theletter “a” meets consonant (closed syllable), it is spoken as/a/. The vowel articulation pattern indicates the first two resonances of vocal tract, F1 for height and F2 for backness. The

Fig. 4. Articulatory pattern for vowels and consonants of Javanese, Sundanese, and Standard Indonesian.
comparison of Indonesian, Javanese, and Sundanese vowel
articulation patterns is shown in Fig. 4 (left side). Consonants
can be made by changing the articulation area, style, and vocal chord condition. The comparison of Indonesian, Javanese,and Sundanese’s consonant articulatory patterns can be seenin Fig. 4 (right side).

ing in a total of 44,000 speech utterances, which amounted
to around 43.35 hours of speech. In this experiments, we use
the clean speech data with standard Indonesian, Javanese andSundanese accents.
4. COLLECTION OF JAVANESE AND SUNDANESESPEECH DATA

3. EXISTING INDONESIAN DATA RESOURCE
4.1. Text Corpus
Indonesian speech corpora were developed by the R&D Division of PT. Telekomunikasi Indonesia (R&D TELKOM) in
collaboration with ATR as a continuation of the APT (Asia
Pacific Telecommunity) project [3, 4].
A raw text source for the daily news task has alreadybeen generated by an Indonesian student [5]. The source wascompiled from “KOMPAS” and “TEMPO”, which are currently the longest and most widely read Indonesian newspaper and magazine, respectively. This source consists of morethan 3160 articles, with around 600,000 sentences. R&D
TELKOM further processed the raw text source to generatea clean text corpus.
From this raw text data, phonetically-balanced sentenceswere selected by using the greedy search algorithm [6]; producing a total of 3168 sentences. Then, clean and telephone
speech were recorded, simultaneously, at sampling frequencies of 16 and 8 kHz, respectively, by R&D TELKOM in
Bandung, Java Island, Indonesia. There were a total of 400
speakers (200 males and 200 females). Four main accentswere covered: Batak, Java, Sunda, and standard Indonesian(without accent). Each speaker uttered 110 sentences, result-

Two documents are collected from newspaper, Mangle3 online collection for Sundanese and Djaka Lodang magazine forJavanese. The initial forms of these documents contain numbers, punctuation, abbreviations, acronyms, names, and foreign words. These documents were then converted to anotherdocuments by:• converting all upper case letters into lower case• removing punctuation• changing numbers into words• select short sentences (max. 20 words for each sentence)
From this text data, we then selected phonetically-balanced
sentences by using the greedy search algorithm[6]; this produced a total of 230 sentences as shown in Table 1.
4.2. Speech Recording
For recording, 20 native speakers were selected, 10 native
speakers (5 males and 5 females) of Java ethnicity and the
3 Majalah Sunda Online – http://www.majalah-mangle.com

other 10 native speakers (5 males and 5 females) of Sunda
ethnicity. Each speaker was asked to read prepared text of the
230 sentences. Speech was recorded in two different places,in Indonesia and Japan. Speech was recorded in a quiet room.
Recording materials were a Sony ECM-674 and a Sennheiser
HMD 280 Pro. Speech was recorded into WAV file at 44.1
kHz sampling frequency 16 bit (sample size). Because thetexts were taken from two different ethnic languages, filenames have to be discriminated. For Sundanese speech
file, the label is EEEXXX F/M L C news Y Y Y Y.wav
where:• EEE is the code for ethnic languages, Jaw for Java and
Snd fo Sunda,• XXX is the order of speaker (in this matter 001-010),• F is female speaker and M for male speaker,• L is another code for ethnic languages, J for Java and S
for Sunda,• C news means this speech built by reading news text
clearly, and• YYYY is the order of speech.

vowel /e/ and /@/ from standard Indonesian. The first chart(shown in Fig. 5) was obtained from female speaker data andthe second chart (shown in Fig. 6) from male. These chartsshow vowels’ location in F1 and F2 scale in Hertz. From
both charts we can see the difference in vowels’ location fromeach language. The lower the F1 value, the higher (closer) the
vowel. For both /e/ and /@/, Sundanese vowels lie on the top ofother languages, followed by Javanese vowels and Indonesianvowels at the bottom. Even for the same vowels, the formant
values of each language are located in a slightly different area.
The reasonable explanation of this phenomenon is the style of
speaking from each ethnic group itself. They use different dialects in speaking (further details can also be found in [8]).
Furthermore, the position of Javanese /E/ lies in middle position closed to Indonesian /e/, while the position of Sundanese/eu/ lies in central-high position. But if we look entirely, thepattern from vowels is similar to articulatory pattern for vowels in Fig. 4.
200

400

e

@
@
eueueu
eu@
@
@
eu @
@
eu
@@
@
@

eu

e e
ee
ee e
e
e
e
e

e

eu

ee

F1 (Hz)Table 1. Javanese and Sundanese Text Corpora
Attributes
Javanese Sundanese
Number of Sentence
230
230
Number of Words
2999
4262
Vocabulary Size
1529
1728
Number of Name Words
24
19
Number of Foreign Words
23eee E E

600

e
e
800

@
EEeE EE
E
E
E
e

@@ @
@@@
@@
@@ @
@
@ @

@
@ @
@ @

e e ee
@

1000
3000

2375

1750
F2 (Hz)1125

500

Fig. 5. Vowel distribution of /e/, /@/, /E/, and /eu/ depending on
F1 and F2 for Javanese, Sundanese, and Indonesian female
speakers.

5. VOWEL ANALYSIS OF JAVANESE AND
SUNDANESE

200

4 Praat:
Doing
Phonetics
http://www.fon.hum.uva.nl/praat/byComputer

–

eu
eu
400
e
e

F1 (Hz)As described in Section 2.2, there is a difference between
vowel articulatory pattern in Indonesian, Javanese, and Sundanese. This section describes the experiment in comparing
Indonesian, Javanese, and Sundanese vowel based on thedata that has been collected. Here, Praat4 tools are used
to create formant charts. Two speakers (female and male)with heavy accents were chosen from each language. Then,the segmented phoneme data from these female and malespeakers was processed separately. Here, we selected only
the phoneme with previous nasal context which is commonlyused in these languages. From the F1 and F2, the formant
charts were obtained (similar with experiments describedin [7]). In all charts, Indonesian vowels from experimentare marked by black font while Javanese vowel are marked
by blue font. In the first two charts, Sundanese vowels aremarked in purple.
First, we examine /e/, /@/, /E/ of Javanese vowels and /e/,/@/, /eu/ in Sundanese vowels. In comparison, we also include

600

e

e
e ee
e

e

e
E

e

e
ee e ee
E e
EEe
eE e e
e E
eEe
E ee
e

@
eu @eu @ @eu@ @ @@@@ @@@@ @ @ @@@@@@ @
@
@
@ @@@
@

800

1000
3000

2375

1750
F2 (Hz)1125

500

Fig. 6. Vowel distribution of /e/, /@/, /E/, and /eu/ dependingon F1 and F2 for Javanese, Sundanese, and Indonesian malespeakers.
Next, we examine /a/, /o/, /O/ of Javanese vowels, in comparison with vowels /a/ and /o/ from standard Indonesian. The
first chart (shown in Fig. 7) was obtained from female speakerdata and the second chart (shown in Fig. 8) from male. Similar tendencies as before, both charts show that the formant
values of /o/ from Javanese are generally lower, meaning thatand study how to build a speech-to-speech translation system
for Indonesian ethnic languages in rapid way by the use ofexisting Indonesian speech recognition.

400

600

O

o o
oo
oo
oO O
O o o
OO O OF1 (Hz)O

7. REFERENCES

o

800
a

aa
aa
aaaa aa
a
aaaa
a

1000

1200
3000

2375

1750
F2 (Hz)

o
o

1125

500

Fig. 7. Vowel distribution of /a/, /o/, and /O/ depending on F1and F2 for Javanese and Indonesian female speakers.
400

oo[1] I. Baidillah, U.A. Darsa, O. Abdurahman, T. Permadi,
G. Gunardi, A. Suherman, T. Ampera, H.S. Purba, D.T.
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o

O

F1 (Hz)[3] S. Sakti, E. Kelana, H. Riza, S. Sakai, K. Markov, and
S. Nakamura, “Recent progress in developing Indonesian large-vocabulary corpora and LVCSR system,” inProc. MALINDO, Cyberjaya-Selangor, Malaysia, 2008,
pp. 40–45.

O
Oo o o oooooo ooo Ooo
oO
O

600
aaa a
a a
aaaaaaaaa a
aa a

800

1000

1200
3000

2375

1750
F2 (Hz)1125

500

Fig. 8. Vowel distribution of /a/, /o/, and /O/ depending on F1and F2 for Javanese and Indonesian male speakers.
the vowels lie higher than those of Indonesian speech. On theother hand, the position of Javanese /O/ lies in middle position
closed to Indonesian /o/. However, the formant values of /a/from Javanese and standard Indonesian lie almost in the same
region.
Comparing the charts obtained from female and malespeakers, the positions of vowels are different. However,anatomically-related acoustic differences in the speech ofmales and females are well-established in the literature[9, 10]. The vocal tract of adult females is shorter thanthat of adult males, causing higher F0 and higher formant
frequencies.
6. CONCLUSION
We have presented the development of Indonesian ethnic
speech corpus, which includes Javanese and Sundanese languages. An experiment to analyze the vowels between Javanese, Sundanese and standard Indonesian has also been
done. The results reveal that even for the same vowels,
the formant values of each language are located in slightly
different area. In other words, the vowels in Javanese andSundanese are acoustically higher than standard Indonesian.
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