BAR113F – BC – cb

Behavior Research Methods, Instruments, & Computers
2004, 36 (3), 531-547

Frequency of occurrence for units of phonemes,
morae, and syllables appearing in a lexical corpus
of a Japanese newspaper
KATSUO TAMAOKA
Hiroshima University, Hiroshima, JapanandSHOGO MAKIOKA
Osaka Women’s University, Osaka, JapanOn the basis of the lexical corpus created by Amano and Kondo (2000), using the Asahi newspaper,
the present study provides frequencies of occurrence for units of Japanese phonemes, morae, and syllables. Among the five vowels, /a/ (23.42%), /i/ (21.54%), /u/ (23.47%), and /o/ (20.63%) showed similarfrequency rates, whereas /e/ (10.94%) was less frequent. Among the 12 consonants, /k/ (17.24%), /t/(15.53%), and /r/ (13.11%) were used often, whereas /p/ (0.60%) and /b/ (2.43%) appeared far less frequently.
Among the contracted sounds, /sj/ (36.44%) showed the highest frequency, whereas /mj/ (0.27%) rarely
appeared. Among the five long vowels, /a/ (34.4%) was used most frequently, whereas /u/ (12.11%)
was not used so often. The special sound // appeared very frequently in Japanese. The syllable combination /k/V// (19.91%) appeared most frequently among syllabic combinations with the nasal //.
The geminate (or voiceless obstruent) /Q/, when placed before the four consonants /p/, /t/, /k/, and /s/,
appeared 98.87% of the time, but the remaining 1.13% did not follow the definition. The special sounds//, //, and /Q/ seem to appear very frequently in Japanese, suggesting that they are not special in termsof frequency counts. The present study further calculated frequencies for the 33 newly and officiallylisted morae/syllables, which are used particularly for describing alphabetic loanwords. In addition, thetop 20 bi-mora frequency combinations are reported. Files of frequency indexes may be downloaded
from the Psychonomic Society Web archive at http://www.psychonomic.org/archive/.

The table of fundamental Japanese sounds, which aredescribed in phonological scripts of two types of kanasymbols, hiragana or katakana, consists of 101 basic
kana, including the special sound of the nasal // (written in hiragana as
and in katakana as ). However, inmodern spoken and written Japanese, it is not unusual tofind some morae that are not described in the traditional
kana table. One of the reasons for this drastic change inJapanese sounds has been the recent, massive adoption ofalphabetic loanwords, especially from English, resulting
in various new sounds in modern Japanese. Taking thisnew trend into consideration, a list of an additional 33
kana (or morae) was officially issued for these loanwords
through a cabinet announcement by the Government ofJapan (1991). Since kana is a shallow script, whereby
orthographic symbols and phonological units correspondto each other on a regular basis, each single kana (occasionally two kana for contracted sounds) corresponds tothe phonological unit of a mora. Thus, by counting kana
The authors express their gratitude to Takayuki Arai and Yasushi Hino
for their valuable assistance in reviewing this article. Correspondence concerning this article should be addressed to K. Tamaoka, International Student Center, Hiroshima University, 1-1, 1-chome, Kagamiyama, HigashiHiroshima, 739-8523 Japan (e-mail: ktamaoka@hiroshima-u.ac.jp).

units, the present study was able to calculate the overallfrequencies of occurrence for Japanese phonologicalunits. Through the use of a lexical corpus (Amano &Kondo,1 2000) produced on the basis of the Asahi newspaper, the present study provides type and token frequencies of occurrences (hereafter, if not clearly mentioned,
frequency refers to frequency of occurrence or frequency
counts) for the units of phonemes, morae, and syllables.
The frequency counts for phoneme, mora, and syllable
units are useful for estimating the phonological familiarityof a Japanese word by adding or averaging frequencies
involved in the target word. For example, the Japanesewriting system includes three scripts: kanji, hiragana,and katakana. Although each word is more likely to be
written in one script than in another, it is possible to transcribe the target word into other scripts. By transcribing
words into unfamiliar scripts, the orthographic familiarity
will be severely reduced. Using this process, Besner and
Hildebrandt (1987) found that loanwords normally written in katakana were named more quickly than both nonwords and kanji compound words presented in katakana.
However, since the same words in different scripts arestill pronounced in the same way, it is quite possible thatphonological familiarity (frequency in sounds) could be
independent of the orthographic familiarity (frequency in531

Copyright 2004 Psychonomic Society, Inc.

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TAMAOKA AND MAKIOKA

print) of the target words. Likewise, Tamaoka and Murata (2001) indicated that CVCVCV-structured nonwords with the same vowel repetitions (e.g., /kohomo/)
were processed more slowly and less accurately thanthose with no repetition (e.g., /kohami/). This tendency
is called vowel repetition effects. However, Tamaoka and
Murata did not use the phonological frequencies of phonemes and morae as a control condition in their experiments. Previous studies involved with the processing
units of Japanese phonology (e.g., Cutler & Otake, 1994;
Otake, Hatano, & Yoneyama, 1996; Otake, Hatano, Cutler,& Mehler, 1993; Tamaoka & Terao, 2004) and with moratiming (e.g., Han, 1992; Sugito, 1989; see Vance, 1987,
and Warner & Arai, 2001, for literature reviews) also havenot provided any frequencies of occurrence for the morae
unit when constructing target words and nonwords.
As can be seen from these works, to develop more precise experimental conditions, frequency counts for thephonological units of phonemes, morae, and syllables
will have to make a greater contribution to various studiesin psychology, linguistics, psycholinguistics, and otherrelated areas in estimating phonological familiarity.

been accelerated, especially in the areas of sports, computers, fashion, and the sciences. Even vocabulary entries in various Japanese dictionaries have a variety ofkatakana spellings for loanwords (Endo, 1989). As such,in daily Japanese publications, various katakana spellings
have been used to describe the same loanwords beyond
the limits of the basic 100 morae and three special sounds(see Appendix A).
Responding to this massive adoption of alphabetic
loanwords, the Government of Japan (1991) officially declared a list of 33 additional morae (see Appendix B) to be
used for presenting these loanwords. This administrativedecision implies an official acceptance of katakana multiple spellings for alphabetic loanwords. Except for /wu/( ), the remaining 32 morae are all contracted sounds,
such as /fo/ infor fork, /kwo/ inforquartz, and /vwe/ infor veil, which were created to describe more accurately the sounds of foreign
words. The type and token frequencies of 100 basic morae,
the special sounds of //, /Q/, and //, and 33 additional
morae (a total of 136 morae) are outlined in Appendixes
A and B.

Changes of Japanese Sounds and Spellings
In the history of the Japanese sound palette, a great alteration occurred through the adoption of various vocabularies from different languages. In the Nara period(A.D. 710–784), Japanese sounds were fundamentally
constructed with a consonant and a vowel (Koizumi,
1990; Komatsu, 1981; Kubozono, 1999; Kubozono &Ota, 1998; Numoto, 1987). There was no need to distinguish between syllables and morae, because they wereidentical in this period. The first alteration came as a result of the influence of the Chinese language. Three special sounds—the nasal //, the geminate (or voicelessobstruent) /Q /, and the long vowel //—were created in
the process of adopting Chinese words into the Japanese
language. These sounds, which were regarded as independent morae, created a distinctive difference between
a mora and a syllable. Sound sequences in which thesesounds occur, such as /ka/, /kaQ/, and /ka/, are counted
as two morae, but only a single syllable.
More recently, additional sounds have come from theadoption of alphabetic languages. These loanwords contained many sounds that could not be easily described in
the traditional Japanese sound system. As a result, theJapanese developed ways to present the specific sounds ofloanwords, using katakana. Kokuritsu Kokugo Kenkyujo[or the National Institute for Japanese Language] (1983)
found 162 loanwords that could be written in two ways.
Endo (1989) has provided a variety of examples, such as/akusesari/ and/akusesari/
for accessories,/webu/ and/uebu/for wave,/wido/ and/uidou/
for window,/amacjia/ 2 and/amactjua/ for amateur. The introduction of dual (oreven triple) spellings into the Japanese vocabulary has

Japanese Sound Structure
Japanese phonemes, morae, and syllables can be portrayed in a single hierarchical structure (Haraguchi, 1996;
Kubozono, 1989, 1995, 1999, 2002; Kubozono & Ota,
1998; Terao, 2002). As is shown in Figure 1, the lowest
phonological level is the phonemic level, representing
consonants (C), semivowels (S), and vowels (V). The
next level is the moraic level. The first mora (µ1) is constructed from four different combinations: a single vowel(ϕV, such as /a/, /e/, and /o/), a consonant and a vowel(CV, such as /ka/, /se/, and /mu/ ), a semivowel and avowel (SV, such as /ja/, /ju/, and /wa/), and a consonant,a semivowel, and a vowel (CSV, such as /tja/, /pjo/, and/mju/). The second mora (µ 2) is represented by four special sounds: two consonants, represented by // or /Q/,and two vowels represented by // and /J /. The dual vowels, such as /ae/, /oi/, and /ou/, are described by a vowel
plus /J /.
The CV-structured morae are also considered to belight syllables; in this sense, these phonetic combinations are classified as syllables, as well as morae. The
highest level in the figure is the syllable level, which involves a combination of the first and the second morae(µ1  µ 2  σ). These combinations are termed heavy
syllables. For example, a CVN syllable /ka/ consists ofthree phonemes (/k/, /a/, and //), two morae (/ka/ and//), and one syllable /ka/. It is also possible to create
a long single syllable, such as CSVRN, as in /tja/, andCSVRQ, as in /pjuQ/ (see more details in Matsuzaki,1994), but frequencies related to combinations of two
special sounds are excluded in this study, due to the rarity of their occurrence. On the basis of these classifications, the present study calculated frequencies of phonemes, morae, and syllables.

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533

Figure 1. Phonological structure of Japanese syllables.

Kana Type and Token Frequencies
As a result of the word printed frequency index created by Amano and Kondo (2000), a very large lexical
corpus of 341,771 words was established from newspapers containing 287,792,797 words, all of which weretaken from the Asahi newspaper printed from 1985 to
1998. At present, this is the largest and the most up-todate word corpus created from calculating the word frequency of occurrence in Japanese written texts. Thus, thepresent study used this database to calculate frequenciesof phonemes, morae, and syllables. The programming
language of MacJPerl 5.15r4J for Macintosh was used torun a calculation procedure.
When referring to frequency of occurrence, two different frequencies are used: type and token. Type frequency counts a word once. For example, according to
the database (Amano & Kondo, 2000), /keitai/ has four
distinguished lexical meanings: 6,457 times for(portable), 3,980 for( form), 58 for(succession), and 1 for( polite form). Whereas the value ofthe token frequency for /keitai/ is 10,496, the value oftype frequency for this sound remains as 4. Likewise, amora /ke/ is counted 4 times for type frequency, whereas
token frequency yields a value of 10,496 for /ke/. A phonemic (a single V) or a moraic (ϕV type) frequency of /i/for the sound /keitai/ is counted 8 times (/i/ phonemes
twice in each of four homophonic words) for type frequency and 20,992 for token frequency. It is interesting
to compare frequency counts in print and sound. The/keitai/ for succession, written with two kanji (),
has a very small value of 4 for token frequency in print,
but a very large value of 10,496 for token frequency insound. As such, this word is very unfamiliar in the written form but is extremely familiar in the phonologicalform.
In order to investigate the differences in frequency ofoccurrence, the type and token frequencies for 101 basic
morae (or kana), are plotted in Figure 2. A majority of

morae are within a range of 0–5,000,000 for token frequency and 0–10,000 for type frequency. The largest
value of token frequency was given to(/i/, ϕV type).
The largest value of type frequency was given to (/u/,ϕV type). It is rather surprising that the special sound //appeared to be very high in both type and token frequencies. As was explained for the alteration of Japanesesounds, the // sound appeared in the process of adopting various Chinese words, so that it is often included inmany Japanese words (see details in Kubozono & Ota,
1998; Matsuzaki, 1994; Numoto, 1987). Although the// sound is identified as special, it is often seen in Japanese words. Vowels of /o/ and /a/, which are regarded as
the first to be acquired among Japanese children, do notappear as often as an independent kana (mora) unit of ϕV.
As is shown in Figure 2, Pearson’s correlation was significantly high between the two frequency counts (n 101; r  .908, p  .01). This result indicates that the frequency indexes of token and type for 101 morae exhibit
almost no difference. A linear regression line is drawn on
a plotted graph ( y  485.15x  140,755, R2  .824). The
resulting correlation was calculated on the basis of moraunits presented by kana symbols, so that phonemic frequencies are not taken into consideration. In the present
study, token frequency is used to calculate frequency
counts of phonemes, morae, and syllables. Thus, frequency of occurrence refers hereafter to token frequency,
unless otherwise specified.
Five Vowels (ϕV) and (V)
Simply speaking, vowels and consonants are distinguished by whether or not they can function as independent morae/syllables. According to this definition, there
are five vowels in Japanese: /a/, /i/, /u/, /e/, and /o/.
When they are independent morae/syllables, their phonological structure is described as ϕV. Since semivowels/w/ and /y/ cannot be independent morae/syllables bythemselves and share characteristics of consonants, they

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TAMAOKA AND MAKIOKA

45,000,000

40,000,000

Token Frequency

35,000,000

30,000,000

25,000,000

20,000,000

y = 485.15x – 140,755, R2 = .824
Pearson’s Correlation, n = 101, r = .908, p < .01

15,000,000

10,000,000

5,000,000

00

10,00020,00030,00040,00050,00060,00070,00080,00090,000Type Frequency
Figure 2. Plotting of mora type and token frequencies.

are categorized slightly differently than regular vowels.
The special sounds //, /Q/, //, and /J/ are, however, considered as single morae.
Table 1 shows frequency counts of the five Japanesevowels as single moraic (kana) units. Among them, /i/ wasthe most frequently used vowel in the form of ϕV, having
a frequency value of 43,985,426 times, or 40.72%. Thismay be caused by the ending of adjective inflections,which are very often a single phoneme and a mora /i/,such as /nemui/ (sleepy in English), /samui/ (cold), and/amai/ (sweet). The second most frequently used vowel
was /u/, having a frequency value of 39,052,254 times,
or 36.16%. Again, this may be caused partly by verb inflections, such as /utau/ (to sing), /arau/ (to wash), and/warau/ (to laugh). The least frequently used vowel was/e/ at 4.41%.
However, when the frequencies of the possible appearances of vowels (V) are counted, all five vowels

Vowel
/a/
/i/
/u/
/e/
/o/
Total

seem to have a much smaller range from 58,172,645 occurrences, or 10.94%, for /e/ to 124,790,724 times, or
23.47%, for /u/. The vowels /a/ and /o/ were less frequently seen in the ϕV structure, but in the V structure
their frequency increased to 23.42% for /a/ and 20.63%
for /o/. Therefore, once all sound combinations wereconsidered, /a/, /i/, /u/, and /o/ showed similar frequencies of occurrence. Yet /e/ remained the least frequently
used vowel among the five.
Consonants (C) and Their Combinations With
Vowels (CV)As can be explained by the changes in Japanese sounds,
the combinations of a consonant and a vowel are considered as typical Japanese morae, evident in the large totalfrequency of 386,480,338. There are 12 consonants in the
CV structure shown in Table 2. Among them, /k/ was themost frequently used consonant, totaling 66,644,942 times,

Table 1Frequency Counts of Vowels (V and V)
ϕV TypeAll Vowels
Count
Frequency (%)
Count
Frequency (%)
6,149,909
5.69
124,536,587
23.42
43,985,426
40.72
114,568,843
21.54
39,052,254
36.16
124,790,724
23.47
4,767,153
4.41
58,172,645
10.94
14,053,377
13.01
109,714,325
20.63
108,008,119
100.00531,783,124
100.00FREQUENCY OF OCCURRENCE FOR JAPANESE PHONOLOGICAL UNITS

535

Table 2Frequency Counts of Consonants and Their Clusters (CV)
Vowel
Total
%
/a/
/i/
/u/
/e/
/o/
2,312,976
0.60
984,460
192,847445,557
182,551
507,561
60,002,817
15.53
16,442,465
5,808,199
9,612,206
11,037,767
17,102,180
66,644,942
17.24
20,530,065
9,926,212
17,211,261
6,823,149
12,154,255
Fricative
46,153,365
11.94
7,932,086
16,518,016
9,271,734
8,127,590
4,303,939
24,536,108
6.35
12,594,714
3,554,252
3,067,681
1,254,559
4,064,902
VoicedStop
9,383,168
2.43
2,749,654
1,177,824
2,758,994
1,591,698
1,104,998
23,005,066
5.95
9,953,427––
7,744,822
5,306,817
20,094,629
5.20
11,996,376
2,009,223
1,210,586
2,328,945
2,549,499
Fricative
12,163,220
3.15
1,384,993
6,550,231
1,644,763
1,646,454
936,779
Nasal
23,748,918
6.14
6,289,027
3,972,466
2,577,386
4,118,162
6,791,877
47,766,161
12.36
10,498,607
14,757,618
411,356
2,771,906
19,326,674
Liquid50,668,968
13.11
6,947,107
6,116,529
28,899,891
5,777,889
2,927,552
Total
386,480,338
100.00108,302,981
70,583,417
77,111,415
53,405,492
77,077,033
Note—The stop /t/ with /i/ is represented by /cji/ (see Appendix A), although it is not indicated in Table 2. /z/ is pronounced /zj/ or /dj/ when it
is combined with /i/, but in this study /zi/ is used to represent this mora (see Appendix A). In this table, /z/ is categorized as a fricative, although/z/ is pronounced either as a fricative or an affricate allophonically.
Voice
Voiceless

Articulation
Stop

Consonant
/p/
/t/
/k/
/s/
/h/
/b/
/d/
//
/z/
/m/
/n/
/r/

or 17.24% of the total CV frequency. The second mostfrequently used consonant was /t/, appearing 60,002,817
times, or 15.53%. The third was /r/ at 50,668,968 times,or 13.11%. The consonant /p/ showed the lowest frequency of 2,312,976 times, or 0.60%. Following this, /b/
was counted 9,383,168 times, or 2.43%. As is shown in
Table 2, /ru/ was the most frequently used among CV
morae (or syllables, since they are identical), with a frequency count of 28,899,891 times. This is because inflections of verbs are often /ru/. The second most frequently used mora was /ka/, being recorded 20,530,065
times. The third was /no/, the fourth was /ku/, and thefifth was /to/. It should be noted that /z/ is pronounced/zj/ or /dj/ when it is combined with the vowel /i/. However, in the present study, /zi/ is used to represent thismora (see Appendix A). Interestingly, the frequency of/zi/ is high—6,550,231 times of occurrence, far beyond
the frequencies of other vowel combinations with /z/.

Frequencies Involving Semivowels (S)In Japanese phonology, from the perspective of thekana script, ϕV and CV mora /syllable sounds are referred to as direct sounds (tan’on in Japanese). Since SV
and CSV mora /syllable sounds are represented by two
kana symbols (the second is written in a smaller sizekana), such as(/kja/),(/sjo/), and(/nju/),
these are called contracted sounds, or palatalized sounds( yoo’on in Japanese). The contracted sounds are constructed with the semivowel /j/3 in their moraic structures, which appear with three vowels—/a/, /u/, and /o/.
The vowels /i/ and /e/ in contracted morae do not appear
in Japanese (they do not contain frequency counts) andare thus called open spaces (akima). They are indicatedby – in Table 3.
Apart from this, both the direct and the contracted
sounds are identical in terms of the use of a single mora
and a single syllable. From the perspective of the kanaTable 3Frequency Counts of Semivowels and Contracted Sounds (SV and CSV)
Vowel
Phonemes
Total
%
/a/
/i/
/u/
/e/
/o/
SV
/w/
3,777,20128.37
3,777,201––/j/
9,536,584
71.63
3,432,278–
1,620,066–
4,484,240
CSV (C/j/V)
Voiceless
Stop/j//pj/
155,382
0.65
95–
29,907–125,380/tj/
3,401,638
14.18
199,251–
995,900–
2,206,487/kj/
3,817,809
15.92
166,750–929,206–
2,721,853
Fricative/j//sj/
8,737,457
36.44
2,138,138–
2,858,438–
3,740,881/hj/
634,527
2.65
53,284–
3,304–
577,939
VoicedStop/j//bj/
179,278
0.75
511–
16,016–
162,751/j/
1,011,811
4.22
59,424–
15,343–937,044
Fricative/j//zj/
3,712,578
15.48
188,263–
1,482,387–
2,041,928
Nasal/j//mj/
63,9220.27
14,646–
15,494–33,782/nj/
460,379
1.92
3,087
–
446,886–
10,406
Liquid/j//rj/
1,806,101
7.53
50,769–214,108–
1,541,224
Note—The overall total of SV frequency is 13,313,785, whereas the overall total of CSV frequency is 23,980,882. The total frequency of /j/ is31,711,365, whereas the total frequency of /w/ is 3,777,201.
Phonemic
Structure

Voice
VoicedArticulation
Semivowel

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TAMAOKA AND MAKIOKA

script, the contracted sounds are combinations of 11 consonants with /j/, which are described by three small kana,(/ja/),(/ju/), and (/jo/), depending on the following vowels (for details, see Amanuma, Otsubo, &Mizutani, 1996). All these contracted sounds containsemivowels within a phonological structure. It should be
noted that the sounds /dj/ and /zj/ are not distinguishedin standard Japanese, although they could be written differently in kana. Thus, they are treated as the same sound,
as represented by /zj/. This resulted in 11 consonants withthe semivowel /j/ in contracted sounds shown in Table 3.
There are two semivowels, /w/ and /j/. As is indicatedin Table 3, /j/ had a much higher frequency (9,536,584
times) than /w/ (3,777,201 times). Among morae of the
SV structure, /jo/ had the highest frequency (4,484,240
times). Only /j/ is combined with consonants, and as isshown in Table 3, there are 11 CS combinations. The
combination /sj/ appeared 8,737,457 times, or 36.44%.
The CS combination /kj/ was the second most frequent,occurring 3,817,809 times. The least used CS combination was /mj/, appearing only 63,922 times, or 0.27%.
The second least used CS combination was /pj/, counted
155,382 times, or 0.65%. Among the CSV moraic units,/sjo/ was the most frequently used, appearing 3,740,881
times. The mora /sju/ was the second most frequently
used, appearing 2,858,438 times. The third was /kjo/ at
2,721,853 times. In contrast, /pja/ was the least frequent,
being counted only 95 times.
Vowel combinations with /w/ are limited to /a/. According to Okumura (1977), /kwa/ and /wa/ were usedin old Japanese but disappeared by the end of the 16th
century. However, /wi/, /we/, and /wo/, including /kwa/,/kwi/, /kwe/, /kwo/, /wa/, /vwa/, /vwi/, /vwe/, and/vwo/, are now revived and used only for newly adopted
katakana loanwords. These morae are included as a partof the aforementioned officially announced 33 sounds(see Appendix B). In contrast, /j/ appears frequently in
Wago (words of Japanese origin) and Kango (words ofChinese origin). The sounds /ja/, /ju/, and /jo/ are usedfollowing various consonants, such as /p/, /s/, /h/, /b/ //,/z/, /m/, and /n/ in both Wago and Kango.
Thirty-Three Additional Morae Used for
Alphabetic Loanwords
According to the 1991 Japanese government guidelines,
33 additional morae (or kana),4 along with the 100 basic
kana and 3 kana for three special sounds, are officially
specified for describing alphabetic loanwords (Tamaoka& Miyaoka, 2003). The type and token frequencies ofthese 33 morae, used only for alphabetic loanwords, arereported in Appendix B. These additional morae showeda wider range of token frequencies. The most frequently
used mora was /ti/ (), being registered 66,313 times.
In fact, /ti/ is used for presenting common loanwords,
such as(/timu/, for team),(/ti/, fortea),(/pati/, for party), and(/boratia/, for volunteer). According to the basic Japa-

nese sound system (i.e., the 101 basic morae), /cji/ for(allophone of the /t/-line mora sounds) was not distinguished from the consonant /t/ for /ta/ ( ), /tu/ ( ),/te/ ( ), and /to/ ( ): These five morae are all classified as /t/-plus-vowel CV morae. However, as Ishihara(1997) has pointed out, modern Japanese can clearly distinguish(/mirukuti/, for milk tea), from(/mirukucji/). Thus, they can easily identify the difference between /ti/ and /cji/. Furthermore,
Ishihara (1997) stated that Japanese also distinguish(/ci/) from(/ti/) and (/cji/) in both speaking
and listening. For example, the name of former Russianpresident Yeltsin is described by(/erici/ ),rather than(/ericji/) or(/eriti/).
A majority of native Japanese speakers can correctly perceive and properly pronounce them as different sounds.
In contrast, the morae, including the contracted soundsof /kw/ with vowels—/kwa/ (), /kwi/ (), /kwe/(), and /kwo/ ()—are rarely seen. The mora
/kwu/ () can exist by simply adding the vowel /u/.
However, instead, /ku/ ( ) is used, so /kwu/ does notappear in Japanese. Although these are new sounds, they
follow the Japanese phonological structure of CSV depicted in Figure 1. The least frequently used mora was/kwe/, which appeared only twice. In the lexical corpusof Amano and Kondo (2000), the mora /kwe/ was used
only for the English loanword sequence, presented as(/sikwesu/ ). Similarly, /kwi/ was thesecond least used mora, appearing 20 times. Examples of/kwi/ include(/kwi/, for queen) and(/kwiteɾto/, for quintet). The mora /kwa/
was used only 21 times: 12 for quartet, presented as(/kwaruteɾto/ ), and 9 for esquire, presented as(/esukwaia/ ). The mora /kwo/
has a slightly higher frequency of 85. This was used forloanwords such as quarter, presented as(/kwota/ ), quality, presented as(/kworiti/), and quarterly, presented as(/kwotari/). Judging from these examples, /kw/ is basically used to describe the English spelling qu, which
also represents the sound /kw/ in English.
Japanese people educated since the Second World War
study English for at least 3 years from Grades 7–9, andusually for 6 years up to Grade 12. As the consonant /v/
is commonly seen in English, some new morae havestarted being used to approximate this English sound.
These have included /va/ (), /vi/ (), /vu/ ( ),/ve/ (), and /vo/ () for describing the /v/ soundin loanwords. Among them, /vi/ is the most common
mora, appearing 733 times as examples in such words as(/venisu/, for Venice),(/sovieto/, forSoviet),(/daiviu/, for diving), and(/riviu/, for living). As all these examples
indicate, the English spelling of vi is described using thecontracted sound of /vi/ in Japanese. Since these words
had previously been written as /bi/ ( ), modern Japanese has begun to distinguish /v/ and /b/ when adopting

FREQUENCY OF OCCURRENCE FOR JAPANESE PHONOLOGICAL UNITS
alphabetic loanwords. Yet native Japanese speakers mostprobably pronounce a fricative consonant /v/ like a stop
consonant /b/ (Matsuzaki, 1993), although they distinguish /v/ from /b/ in the katakana script.
Another interesting aspect of the new 33 morae is theexistence of the consonant /f/, which is not described in
the table of 101 basic Japanese morae. Jouo (1977) has
claimed that a combination of /f/ 5 plus /a/ is already accepted by native Japanese speakers to describe alphabetic
loanwords as examples of(/faito/, for fight)
and(/fasuto/, for first). Koizumi (1989,1990) and Ishihara (1995) also have suggested that /f/ is
an independent consonant within the collection of Japanese sounds, although it is not included in the table of
101 fundamental Japanese morae. In fact, according to
our index of frequency counts, the consonant /f/ extended to other vowels and is now found in /fa/ (),/fi/ (), /fe/ (), and /fo/ (). In comparison
with other additional morae (see Appendix B), the frequencies of these morae are relatively high at 60,484
times for /fa/, 50,615 times for /fi/, 16,129 times for /fe/,and 31,399 times for /fo/. Since frequencies concerning
the combination of /f/ plus vowels are high among the
33 morae, the consonant /f/ seems to have infiltrated into
Japanese sounds. However, Ishihara (1995) has noted
that, in general, native Japanese speakers have not yet
been able to distinguish /fa/ from /ha/, /fe/ from /he/,and /fo/ from /ho/ in speaking (i.e., production).
Syllables With Dual Vowels/Diphthongs (VJ)
and Long Vowels (VR)
As is depicted in Figure 1, the structure of CVV (bothdual vowels/diphthongs of CVJ and long vowels of CVR)
is regarded as two morae, CV and V (V can be either /J/or //), but as a single syllable. The frequency of occurrence for these sounds is shown in Table 4. Taking twovowels for V1V2 positions that are interchangeable, there
were 25 different combinations of the two vowels. Whenthe first and the second vowels were the same, they wereconsidered long vowels. In Table 4, these were shown infive diagonal cells. When the first and the second vow-

Following/a/Vowels(/J/ or //) Pair
Count
/a/
a
1,236,532/i/ai 17,710,419/u/au
994,228/e/ae
1,329,310/o/ao
372,343
Total
21,642,832

537

els differed, they were recorded as dual vowels, totaling
20 cases. Although the 25 two-vowel combinations added
up to a total frequency of 72,657,680 times, these sounds
were not unusual in terms of occurrence in Japanesewords. It should be noted that a word such as tousan, meaning father, is very often pronounced as /tosa/ with along vowel, not two vowels. Furthermore, vowel combinations of -ei and -ou are often pronounced as long vowels.
However, since the original database of Amano and Kondo(2000) does not distinguish whether or not these two consecutive vowels are long vowels, these differences are nottaken into consideration in the present frequency counts.
The total frequency of the five long vowels was
3,600,096 times. Among the five long vowels, /a/ showed
the highest frequency of 1,236,532 times, 1.70% of thetotal dual/long-vowel frequency, or 34.35% of the total
for the five long vowels. The long vowel of /i/ was thesecond highest in frequency, appearing 733,413 times,
or 1.01% (or 20.37% of the five vowels). Third was /e/,appearing 634,079 times, or 0.87% (or 17.61% of thefive vowels), and fourth was /o/, appearing 560,222, or
0.77% (or 15.56% of the five vowels). The lowest was /u/,which occurred just 435,850 times, or 0.60% (12.11% of
the five vowels). However, it should be noted that, due todifficulties involved in the differentiation of words’ moraic
segmentations, the token and type frequencies of a longvowel // include two continuous vowels, such as in/baai/, meaning case, which is usually segmented into
two morae of /ba/ and /ai/.
Twenty dual vowels were counted up to 69,057,584
times. Among them, the highest frequency rate was /ou/,
showing 27,448,213 times, or 37.78%. The second was/ai/ at 17,710,419 times, or 24.38%. The third was /ei/ at
12,199,230 times, or 16.79%. Surprisingly, these threecombinations make up 78.95% of all the 25 combinations. More specifically, the term dual vowel, or diphthong, refers to two continuous vowels (e.g., /ai/, /au/,/oi/) that change from an open vowel (i.e., /a/, /o/) to aclosed vowel (i.e., /i/, /u/). The vowel /e/ is between the
open and the closed vowels. Two continuous vowels,such as /ia/, /uo/, and /io/, which change from a closed

Table 4Frequency Counts of Dual Vowels (/J /) and Long Vowels (//)Previous Vowels (V)
/i/
/u/
/e/
/o/
%
Pair
Count
% PairCount% Pair
Count
%
Pair
Count
%
1.70 ia 1,049,302 1.44 ua
246,548 0.34 ea
493,440 0.68 oa
78,570 0.11
24.38 i733,413 1.01 ui 2,048,443 2.82 ei 12,199,230 16.79 oi
1,306,835 1.80
1.37 iu 1,223,360 1.68 u
435,850 0.60 eu
12,575 0.02 ou 27,448,213 37.78
1.83 ie
561,233 0.77 ue
695,410 0.96 e
634,079 0.87 oe
369,639 0.51
0.51 io
411,375 0.57 uo
255,949 0.35 eo
251,162 0.35 o
560,222 0.77
29.79
3,978,683 5.48
3,682,200 5.07
13,590,486 18.70
29,763,479 40.96

Note—The five shaded diagonal cells are long vowels. The overall total of frequencies in Table 4 is 72,657,680. Specifically, the term dual vowel,
or diphthong, refers to two continuous vowels (e.g., /ai/, /au/, /oi/) that change from an open vowel (i.e., /a/, /o/) to a closed vowel (i.e., /i/, /u/).
The vowel /e/ is between the open and closed vowels. Two continuous vowels, such as /ia/, /uo/, and /io/ which change from a closed vowel to an
open vowel, are considered to be two independent vowels (see Kubozono, 1999).

538

TAMAOKA AND MAKIOKA

vowel to an open vowel, are considered to be two independent vowels (see Kubozono, 1999). There are 8 dual
vowels out of 20 combinations based on this definition(i.e., /ai/, /au/, /ae/, /oi/, /ou/, /oe/, /ei/, and /eu/), whichwere counted 61,370,449 times, or 84.48% of the 20
vowel combinations. This suggests that the majority of
two continuous different vowel combinations are opento-closed dual vowels. Since Table 4 provides frequency
counts for all possible consecutive vowels, all the different
two-vowel combinations are labeled “dual vowels” inTable 4. Thus, the difference between continuous (i.e., dual
vowel or diphthong) and independent vowels should be
carefully treated when using frequency counts in Table 4.
Long vowels placed after consonants (C), semivowels (S), and consonants plus semivowels (CS) are considered as syllabic units, as is depicted in Figure 1. Their
token frequencies are shown in Table 5. Among these
combinations, /pa/ appeared most frequently, at 407,453
times. The second was /ta/ at 229,783 times. The third
was /me/ at 174,212 times, and the fourth was /ri/ at
157,583 times. The consonant /p/ was combined most fre-quently with five long vowels and was counted 581,256
times, whereas the second was /r/ at 507,423 times. Longvowels are also combined with the semivowels /w/ and /j/.
The semivowel /w/ is compounded only with /a/ and wascounted 42,893 times. In contrast, the semivowel /j/ iscombined with three long vowels—/ja/, /ju/, and /jo/.
In addition, various contrastive sounds with /j/ are also tiedwith these three different long vowels, shown in Table 5.
Among them, the most frequently appearing sound was/nju/ at 72,726 times. The second was /pju/ at 28,837
times, and the third was /zja/ at 21,755 times.
Long Vowels in Katakana Loanwords
A katakana symbol offor the long vowel //, as in(/kohi/, meaning coffee), is used for alphabetic loanwords. The total frequency of katakana appearances was 28,464,753 times in the database of the
Asahi newspaper. By counting only katakana, Table 6
provides the top 20 frequently printed katakana. The result is noteworthy in that the special sound of the longvowel // was the highest, appearing 2,860,333 times, orTable 5Frequency Counts of Syllables With Long Vowel // ( type)
Total
Vowel
Frequency
%
/a/
/i/
/u/
/e/

ϕ
/p/
/t/
/k/
/s/
/h/
/b/
/d/
//
/z/
/m/
/n/
/r/

229,142581,256
358,111309,283
217,669
76,375
206,895
78,78477,532
65,767
236,140
106,216
507,423

With Consonants (ϕVR or CVR)
6.74
51,75331,871
1,806
17.10
407,453
70,9417,240
10.54
229,783
46,703
2,489
9.10
128,888
31,20017,828
6.40
69,847
96,09625,7082.25
14,443
6,388
2,517
6.09
73,32952,46718,4422.32
33,435__2.28
10,85732,4102,015
1.93
13,814
43,638
1,838
6.95
33,0506,556
10,031
3.12
34,166
31,2175,452
14.93
38,329157,583
141,091/w//j/

42,89387,314

1.26
2.57

/pj/
/tj/
/kj/
/sj/
/hj/
/bj/
/j/
/zj/
/mj/
/nj/
/rj/
Total

28,89725,394
8,090
20,1203,127
15,460272
32,055
6,387
72,922
5,634
3,399,158/o/

50,81033,85051,41863,60918,067503
26,75632,034
17,723518
174,21219,008108,136

92,902
61,772
27,71867,758
7,951
52,52435,901
13,315
14,527
5,959
12,291
16,37362,284

With Semivowels (SVR)
42,893
–
5,392
–

–
–

–
47,244

–
–
–
–
–
–
–
–
–
–
–
596,644

60
1,760
432
8,968
303
20
245
4,610
0
193
39
535,149–
34,678With Contracted Sounds (CSVR)
0.85
0–28,8370.75
15,579
–
8,055
0.24
0
–
7,658
0.59
5,698
–
5,454
0.09
0
–
2,824
0.45
0
–
15,440
0.01
15
–
12
0.94
21,755
–
5,690
0.19
48
–
6,339
2.15
3
–
72,726
0.17
8
–
5,587
100.001,230,538
607,070429,757

Note—There are more combinations of consonants with // that are not listed in Table 5.
Thus, the total frequency of a single // (3,607,169) in Appendix A is higher than the total of
3,399,158 shown in Table 5.

FREQUENCY OF OCCURRENCE FOR JAPANESE PHONOLOGICAL UNITS

Table 6The 20 Most Frequently Used Katakana Symbols
Ranking
Katakana
Sound
Frequency%1//2,860,333
10.05
2
//
2,119,234
7.45
3
/ru/
1,448,895
5.09
4
/su/
1,336,665
4.70
5
/to/
1,188,192
4.17
6
/i/
936,7913.29
7/a/932,2223.28
8/ra/905,0313.18
9/ri/
783,483
2.75
10
/ru/
742,272
2.61
11
/ Q/
631,694
2.22
12
/ka/
620,694
2.18
13
/ta/
559,735
1.97
14
/do/
558,191
1.96
15
/ro/
528,947
1.86
16
/ri/
449,324
1.58
17
/ko/
418,221
1.47
18
/ma/
411,896
1.45
19
/me/
411,418
1.45
20
/bu/
406,179
1.43
Note—The total of katakana frequencies was 28,464,753. Percentagesof katakana frequencies were calculated on the basis of the overall totalof 28,464,753. Shaded rows indicate the three special sounds.

10.05% of the total katakana frequency. The second mostfrequently used katakana was the special sound of thenasal //, showing a high frequency of 2,119,234 times,or 7.45%. The special sound of the geminate /Q/ came inat the 10th position, appearing 631,694 times, or 2.22%.
These three special sounds were counted 5,611,261 times,
or 19.72%. This result interestingly implies that the special sounds are not exceptional but are, rather, inclined
to be commonly used in Japanese alphabetic loanwords.
Syllables Ending With a Nasal (N)
Phonetically speaking, the Japanese geminate /N/ hasfour sounds: [n], [m], [ŋ] and [].6 Typical examples ofthese include the [n] in kandai (/kadai/), meaning generous, [m] in danboo (/dabo/), meaning heating, [ŋ]in bunka (/buka/), meaning culture, and [] in kekkon(/keQko/), meaning marriage ( [] is used in the endingof words). However, these four phonetic sounds are allperceived as the single phoneme // by native Japanese
speakers. It is also surprising that // was counted at anextremely high frequency of 35,719,268 times. WhenJapanese borrowed a variety of Chinese words, the special
sound // was heavily adopted to Japanese sounds (fordetails, see Tamaoka, 2003; Tamaoka, Kirsner, Yanase,Miyaoka, & Kawakami, 2002). In this sense, // is nolonger special with regard to frequency of occurrence.
As is depicted in Figure 1, the single syllables of ϕVN,
CVN, SVN, and CSVN are considered as two morae ofCVN, SVN, or CSVN, since // is regarded as asingle mora. The frequencies of N syllables are listed
in Table 7. Combinations of /k/V// (i.e., /ka/,/ki/, /ku/, /ke/, and /ko/) showed the highest fre-539

quency at 6,986,514 times, or 19.91%. Among them,/ka/ was the most frequently repeated syllable, being
recorded 3,044,363 times. The second most frequently
repeated syllable combination was /s/V// (i.e., /sa/,/si/, /su/, /se/, and /so/ ). This combination wascounted up to 5,998,668 times, or 17.10%, although/su/ had a very low count—only 7,513 times. As compared with morae of ϕV and CV with // combinations,morae with semivowels (i.e., SV and CSV) with // aremuch less frequently constructed. Among these less frequent morae, the highest was /zj/V//, being recorded
275,110 times, or 0.78%. As is shown in Table 7, the six
combinations /pja/, /pju/, /hja/, /hju/, /bja/, and/bjo/ did not appear at all.
Syllables With a Geminate (Q and Q)The geminate /Q/ is depicted by a small kana symbolofin hiragana and byin katakana. However, alarger version of the same symbol
in hiragana orin katakana represents the mora sound /tu/, which has
nothing to do with the geminate /Q/. This sound difference
is much easier to recognize when words using the geminate /Q/ are depicted in the alphabetized script roma-ji. A
few examples from the Japanese language are hattatsu(/haQtatu/ in phonemic symbols, meaning development),
kippu (/kiQpu/, meaning ticket), kakki (/kaQki/, meaningvitality), and masshiro (/maQsiro/, meaning snow-white).
As can be seen in roma-ji, any one of the consonants /p/,/t/, /k/, and /s/ may be geminates. In fact, the geminate/Q/ represents the duration, approximately the time ofone mora, in which one pauses with one’s mouth in the
shape of the following consonant before pronouncing it(Kawakami, 1977; Komatsu, 1981). In this sense, /Q / isalso referred to as a double consonant.
The geminate /Q/ does not occur in the onset and thecoda of words but is always found in the middle of words.
Thus, phoneme and mora frequencies (a syllable with Q)
before /Q/ are shown in Table 8 as Q, and those after /Q/
are shown in Table 9 as Q.
As is shown in Table 8, the vowel /i/ in ϕV was mostfrequently positioned before /Q/. The frequency of /iQ/syllable was 545,475 times. In fact, it is easy to find somefrequently used expressions, such as /iQpa/, meaning
general, /iQsyo/, meaning together, and /iQkai/, meaning
once. The second was the /kaQ/ syllable, being recorded
454,858 times, often seen in /kaQpatu/, meaning active,/kaQsoro/, meaning a runway, and /kaQkaza/, meaning an active volcano. The third was the /keQ/ syllable,counted 363,962 times. In contrast, the six syllables of/pjaQ/, /pjuQ/, /pjoQ/, /bjoQ/, /mjuQ/, and /mjoQ/ did
not exist in the lexical corpus. Among the Q syllables
with semivowels, /sjuQ/ was the most frequently recorded
at 174,082 times. An example of this is /sjuQseki/, meaning attendance.
On the basis of a common definition (e.g., Kawakami,1977), the actual sound of /Q/ is not voiced but has a single mora duration of one of the five consonants [p], [t],540

TAMAOKA AND MAKIOKA
Table 7Frequency Counts of Syllables With Nasal // ( type)
Total
Vowel
Frequency
%
/a/
/i/
/u/
/e/
With Consonants (ϕVN or CVN)
9.54
576,458 1,311,153
253,4850.77
136,061
40,626
11,2504.28
443,181
95,0991,185
19.91 3,044,363
975,378
52,10517.10 1,764,878 1,915,600
7,513
8.43
886,479
233,514243,219
3.67
295,866
64,245774,0313.64
836,265––5.30
151,909
193,500
275,756
5.92
101,720
813,7328,560
6.31
448,183
793,675
364
8.95
341,757 1,082,676
737
4.28
293,375
254,448
5,465

ϕ
/p/
/t/
/k/
/s/
/h/
/b/
/d/
//
/z/
/m/
/n/
/r/

3,346,672
271,632
1,502,415
6,986,514
5,998,668
2,956,124
1,287,350
1,277,236
1,860,202
2,076,189
2,213,553
3,139,702
1,502,421/w//j/91,97592,9740.26
0.27

With Semivowels (SVN)
91,975
–
–
5,707
–
809

203
45,357
20,125
129,765244
2
1,471
275,110
6,005
238
201
35,082,145

0.00
0.13
0.06
0.37
0.00
0.00
0.00
0.78
0.02
0.00
0.00
100.00With Contracted Sounds (CSVN)
0–044,736–
209
20,089–2
14,514–60,730
0
–
0
0
–
2
1,423
–
45
15,994–249,357
4,277
–
1,722
30
–
131
192
–
7
9,519,432 7,773,646 1,946,684

/pj/
/tj/
/kj/
/sj/
/hj/
/bj/
/j/
/zj/
/mj/
/nj/
/rj/
Total

/o/

1,062,207
25,736
796,6142,221,991
2,106,924
274,897
132,820
369,078
1,219,511
1,109,929
268,992
1,693,767
642,304

143,369
57,959166,336
692,677
203,753
1,318,015
20,38871,893
19,52642,248702,339
20,765306,829–––86,458

–
–
–
–
–
–
–
–
–
–
–
11,924,770

203
412
34
54,521
244
0
3
9,759
6
77
2
3,917,613

Note—There are more combinations with //. Thus, the total frequency of a single //(35,719,268) is higher than the total of 35,082,145.

[k], [s], and [ʃ] placed after /Q/. Table 9 shows the frequencies of the four phonemes /p/, /t/, /k/, and /s/ ( [ʃ] is
included in /s/) placed after /Q/. These combinations are
depicted by shadow in Table 9, with frequencies equaling 4,683,681 times, or 98.87% of the total combinations. /Qka/ was the highest frequency, having a rate of
624,174 times. /Qte/ was the second at 507,742 times,
and /Qto/ was the third at 421,717 times.
There were 53,656 cases (1.13% of Q combinations) of deviations from the traditional definition of /p/,/t/, /k/, and /s/ after /Q/. Among them, /d/, /h/, //, and /z/
after /Q/ were counted 52,969 times. Among these consonants, /d/ was the most frequently placed after /Q/, being
counted 22,872 times, or 0.48%. A phonemic combination of /Qdo/ showed the highest frequency at 22,379
times. These new combinations with /Q/ suggest thatJapanese sounds have gradually diversified by adopting
various alphabetic loanwords, especially from English.
Index of Bi-Mora Frequency Counts
An index for how often two moraic units are combined
among Japanese words is called a bi-mora frequency ofoccurrence. Since all Japanese words can be presented inkana, bi-mora frequencies are calculated on the basis of
two kana combinations. For example, the combination of
the morae /hi/ ( ) and /to/ ( ) appears as a word unit
229,773 times, whereas the same combination appears
615,869 times as a part of words, including its combination
as a single word /hito/, meaning human. The index of bimora frequencies of occurrence regarding 4,624 two-kana(mora) combinations with a total of 298,339,034 times areprovided as an Excel file in the order of high to low, including 224 bi-mora combinations of 0 frequency counts.
The top 20 bi-mora frequency counts are reported inTable 10. There were 10 bi-mora combinations of CV
plus V in the top 20. Furthermore, 5 bi-mora combinations were CV plus the special sound // among the top
20. Only 3 bi-mora combinations were CV plus CV in the
top 20 (i.e., /su/  /ru/, /re/  /ru/, and /ko/  /ku/). In
the frequency ranking, the combination of /ka/ and /i/ was
the highest, being counted 4,269,940 times. Second was/te/ and /i/ at 3,851,691 times. Third was /ko/ and /u/, occurring 3,669,655 times; fourth was /se/ and /i/, being
counted 3,661,544 times. These top 4 bi-mora combinations are all CV plus V combinations. The combination of/ka/ plus // was fifth, appearing 3,044,363 times.

FREQUENCY OF OCCURRENCE FOR JAPANESE PHONOLOGICAL UNITS
Table 8Frequency Counts of Syllables With Geminate /Q / (Q )
Total
Vowel
Frequency
%
/a/
/i/
/u/
/e/

ϕ
/p/
/t/
/k/
/s/
/h/
/b/
/d/
//
/z/
/m/
/n/
/r/

693,336
38,604
316,090
1,088,220
415,492
531,613
168,535
104,491
206,361
330,426
240,152
237,301
201,010

/w/
/j/

8,899
131,420

/pj/
/tj/
/kj/
/sj/
/hj/
/bj/
/j/
/zj/
/mj/
/nj/
/rj/
Total

0
41,906
12,754
210,130
12,700390
4,108
27,1138
119
6,256
5,027,434/o/With Consonants (ϕVQ or CVQ)
13.79
67,060545,475
52,4350.77
8,378
16,216745
6.29
98,351
14,5868,153
21.65
454,858
50,820
9,056
8.26
90,730102,5259,479
10.57
344,826
48,09750,7843.35
42,753
16,51175,9642.08
90,999––4.10
181,921
5,717
3,128
6.57
24,293272,866
10,6404.78
61,06454,495
1,802
4.72
21,264
162,392
34
4.00
38,11378,5172,250

19,642
8,473
81,718363,962
185,670
3,255
23,594
3,453
12,72819,338
14,237
48,63135,6948,724
4,792
113,282
209,524
27,08884,651
9,713
10,0392,867
3,289
108,554
4,980
46,436

With Semivowels (SVQ)
8,899–
36,591––––
87,670

–
–
–
–
–
–
–
–
–
–
–
820,395

033,158390
20,435
977
0
177
362
0
20
1,306
778,434

0.18
2.61

–
7,159

With Contracted Sounds (CSVQ)
0.00
0
–
0
0.83
8,745
–
3
0.25
12,324–40
4.18
15,613–174,082
0.25
11,673
–
50
0.01
116
–
274
0.08
3,839
–
92
0.54
5,462
–
21,289
0.00
8
–
0
0.00
86
–
13
0.12
118
–
4,832
100.00 1,628,084 1,368,217 432,304

The bi-mora frequencies are also arranged in 100 
102 bi-mora matrix providing bi-mora frequency counts
not only for ϕV and CV combinations, but also for thecontracted sounds CSV and SV and two special sounds// and /Q/. A 68  68 matrix excluding the contracted
and special sounds is also provided, since the simple
moraic combinations of ϕV and CV are often preferred
for constructing stimuli in psychological experiments inphonology. Although it is well known that word frequency affects phonological processing (e.g., Fushimi,
Ijuin, Patterson, & Tatsumi, 1999; Hino & Lupker, 1998;
Taft, 1979, 1991), it has not yet been clearly indicatedwhether or not bi-mora frequency of occurrence affects
Japanese phonological processing independently fromword frequency. Thus, the bi-mora frequencies of occurrence are also provided by the Web-accessible database.
Web Sites of the Frequency Indexes ofPhonemes, Morae, Syllables, and Bi-Morae for
Downloading
Four separate zip files containing Excel files may be
downloaded from the Psychonomic Society Web archive,
http://www.psychonomic.org/archive/. The database isstored as (1) bi-mora_frequency_index.zip (58.15K),
providing the bi-mora frequency index, (2) bi-mora_541

matrix_100.zip (24.77K), providing the 100  102 bimora matrix Excel table, (3) bi-mora_matrix_68.zip(17.74K), providing the 68  68 bi-mora matrix Exceltable, and (4) frequency_index.zip (11.78K), containing
the frequency indexes of phonemes, morae, and syllables.
The data above may also be accessed from the homepageof Katsuo Tamaoka on the Web site of Hiroshima University, Japan, http://home.hiroshima-u.ac.jp/ktamaoka /(Excel, zip, and PDF files).
Summary
In order to provide phonological familiarity, the present
study has reported frequency counts for units of Japanesephonemes, morae, and syllables, using the word printed
frequency index constructed from 1985 to 1998 editionsof the Asahi newspaper (originally prepared by Amano& Kondo, 2000).
Frequency counts provide a clear picture of trends inJapanese phonology. The type and token frequency of
101 moraic units represented by kana indicated a highcorrelation (r  .908), suggesting no difference between
type and token frequency counts of kana units. Amongthe five vowels appearing as a single unit (ϕV), /i/ wasthe most frequent, whereas /e/ was the least frequent.
Once all possible combinations with the five vowels

542

TAMAOKA AND MAKIOKA
Table 9Frequency Counts of Geminate /Q / and Mora Combinations (Q )
Total
Vowel
Frequency
%
/a/
/i/
/u/
/e/

/o/

With Consonants (QϕV or QCV)
0.00
0
0
0
11.59
216,237
24,64995,27427.87
275,356
93,811
21,67732.17
624,174 150,228 208,466
15.29
120,915 237,532
59,722
0.26
1,365
83
10,461
0.01
91
0
398
0.48
492
–
–
0.22
142
38
9,988
0.16
1
5,514
1,854
0.00
0
0
0
0.00
0
0
0
0.00
31
1
0

0
26,377507,742
135,416
206,956
26
1
1
0
0
0
0
0

0
186,644421,717405,941
99,052603
1022,379220005With Semivowels (QSV)
0
–
0
–

–
–

–

–
–
–
–
–
–
–
–
–
–
–
876,519

120,252
26,742
112,059
113,386
0
0
0
85
0
0
0
1,508,897

ϕ
/p/
/t/
/k/
/s/
/h/
/b/
/d/
//
/z/
/m/
/n/
/r/

0
549,181
1,320,303
1,524,225
724,177
12,538500
22,872
10,190
7,369
0
0
37

/w/
/j/

0
0

/pj/
/tj/
/kj/
/sj/
/hj/
/bj/
/j/
/zj/
/mj/
/nj/
/rj/
Total

120,286
81,362
143,512220,635
0
0
3
147
0
0
0
4,737,337

0.00
0.00

–
0

With Contracted Sounds (QCSV)
2.54
34
–
0
1.72
27,878–26,742
3.03
4,150–
27,303
4.66
31,402–75,847
0.00
0
–
0
0.00
0
–
0
0.00
0
–
3
0.00
62
–
0
0.00
0
–
0
0.00
0
–
0
0.00
0
–
0
100.00 1,302,330 511,856 537,7350Note—Shaded rows indicate syllables following the traditional Q structures.

were included in frequency counts, this trend changed:/u/ became the most and /e/ remained the least frequent.
Among the 12 consonants, /k/ showed the highest counts,
whereas /p/ showed the lowest. The present study has
also reported contracted sounds. The /sj/ with vowels appeared most frequently. Among the CSV moraic units,/sjo/ appeared most frequently, whereas /pja/ was theleast, being counted only 95 times. The Japanese government provided guidelines of katakana usages for alphabetic loanwords, by officially recognizing an additional 33 moraic expressions. Among these, /ti/ appeared
most frequently. The consonant /f/ for /fa/, /fi/, /fe/, and/fo/ is already accepted in Japanese sounds, appearing at
a relatively high frequency of 60,484 times.
The present study has provided frequency counts for
special sounds. Among the five long vowels, /a/ showed
the highest frequency, whereas /u/ was the lowest frequency. It was also interesting to find that the long vowel// (represented by a horizontal line
in katakana) appeared the most frequently in katakana-presented loanwords. The study also showed that the special sound //appeared very often, being counted 35,719,268 times.
Among various syllabic combinations including //, thecombination of /k/V// showed the highest frequency
counts. At 7,858,931 times, the special sound /Q/ wasalso found to appear very frequently. The frequency of/iQ/ was the highest among the combinations with /Q /. As
such, frequency counts tell us that the three well-known
special sounds are actually not special in terms of occurrence in a Japanese newspaper.
Table 10The Top 20 Bi-Mora Frequency Counts
No.
Kana
Phonemes
Frequency%
1/ka//i/
4,269,940
1.43
2/te//i/
3,851,691
1.29
3/ko//u/
3,669,655
1.23
4/se//i/
3,661,544
1.23
5/ka///3,044,363
1.02
6/i//ru/
3,016,280
1.01
7/su//ru/
2,935,841
0.98
8/to//u/
2,708,5380.91
9/na//i/
2,653,620
0.89
10/re//ru/
2,643,2580.89
11/ta//i/
2,632,623
0.88
12/u//si/
2,282,4220.77
13/ke///2,221,991
0.74
14/da//i/
2,120,498
0.71
15/se///2,106,924
0.71
16/jo//u/
1,999,2080.67
17/do//u/
1,930,2170.65
18/si///
1,915,600
0.64
19/ko//ku/
1,851,379
0.62
20/sa///1,764,878
0.59
Note—The total of bi-mora token frequencies is 298,339,034.

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NOTES
1. In this article, including references, an alphabetic description ofJapanese names follows the commonly used Hepburn style. Since the
Hepburn style does not distinguish between long and short vowels (e.g.,
the proper name of Kondo is pronounced /kodo/ with a long vowelat the end), this article uses the spelling of Kondo, not Kondoo. However,to represent precise sounds, Japanese titles of research papers that include
long vowels are shown by repeating the same vowels twice, such as oo.
2. The phonemic symbol /j/ is used for semivowels in contracted
sounds, such as /kja/ (), /pja/ (), and /bjo/ (). Instead of/j/, some phonologists use /y/ for the same sound. The capital J or /J /

544

TAMAOKA AND MAKIOKA

refers to the second vowel in dual-vowel combinations. For example,
since /kai/ contains dual vowels of /ai/, it is described as CVJ (consonantvowelvowel). As such, a small letter /j/ and a capital J refer todifferent phonological elements.
3. The phonemic symbol /j/ usually refers to contracted moraic
sounds. However, the expression /j/ is occasionally used for noncontracted sounds. Although Hattori (1955) used /ci/ for the same sound,
Matsuzaki (1993) used /j/ for /cji/ ( ). In this article, we adapted thesystem of phonemic expressions provided by Matsuzaki.
4. There is no clear outline to express all Japanese sounds perfectly
using phonemic symbols. In order to avoid overlaps of phonemic symbols as much as possible, we set a standard to use /cji/ for(allophoneof the /t/-line mora sounds), /ti/ for, and /ci/ for. Hattori(1955) described the /t/-line morae as /ta/, /ci/, /cu/, /te/, and /to/. How-ever, he did not discuss about a newer mora,. After this mora became
popular, Matsuzaki (1993) adapted a different way, using the phonemic
symbols /ci/ for, /ti/ for, and /cji/ for . The phonemic expressions in the present study are basically adapted from Matsuzaki(1993). The phonemic expression /c/ is also used for /ca/ for, /ce/
for, and /co/ for(see Appendix B). The actual debate on
this issue is much more complicated (see the detailed discussions in
Hattori, 1955, 1956, 1958; Ishihara, 1997; Matsuzaki, 1993, 1994).
Since this issue is beyond the scope and purpose of this article, thisquestion is only briefly mentioned.
5. The phoneme /f/ refers to an unvoiced labio-dental fricative or an
unvoiced bilabial fricative.
6. The brackets, [ ], refer to phonetic symbols, whereas backslashes,/ /, refer to phonemic symbols.

FREQUENCY OF OCCURRENCE FOR JAPANESE PHONOLOGICAL UNITSAPPENDIX A
Frequency Counts of the 100 Basic Morae and Three Special Sounds
Phonemic
Combination

MoraCons/Semi

1
2
3
4
5

ϕV
ϕV
ϕV
ϕV
ϕV

a
i
u
e
o

ϕ
ϕ
ϕ
ϕ
ϕ

6
7
8
9
10
11
12
13
14
15
16
17
18
19
20

CV
CV
CV
CV
CV
CV
CV
CV
CV
CV
CV
CV
CV
CV
CV

pa
pi
pu
pe
po
ta
cji
tu
te
to
ka
ki
ku
ke
ko

21
22
23
24
25
26
27
28
29
30

CV
CV
CV
CV
CV
CV
CV
CV
CV
CV

31
32
33
34
35
36
37
38
39
40
41
42
43

Vowel

Katakana

Token Frequency

Type Frequency

Vowels /a/, /e/, /i/, /o/, and /u/
a
i
u
e
o

6,149,909
43,985,426
39,052,254
4,767,153
14,053,377

18,89867,64384,624
14,10322,195

p
p
p
p
p
t
cj
t
t
t
k
k
k
k
k

/p/, /t/, and /k/ (Voiceless, Stop)
a
i
u
e
o
a
i
u
e
o
a
i
u
e
o

984,460
192,847445,557
182,551
507,561
16,442,465
5,808,199
9,612,206
11,037,767
17,102,180
20,530,065
9,926,212
17,211,261
6,823,149
12,154,255

2,937
1,343
3,480
1,165
2,183
27,384
19,48222,853
12,822
27,131
43,982
31,18338,35914,87327,551

sa
si
su
se
so
ha
hi
hu
he
ho

s
s
s
s
s
h
h
h
h
h

/s/ and /h/ (Voiceless, Fricative)
a
i
u
e
o
a
i
u
e
o

7,932,086
16,518,016
9,271,734
8,127,590
4,303,939
12,594,714
3,554,252
3,067,681
1,254,559
4,064,902

22,624
40,58522,763
16,836
8,857
12,91911,507
11,707
2,633
8,336

CV
CV
CV
CV
CV
CV
CV
CV
CV
CV
CV
CV
CV

ba
bi
bu
be
bo
da
de
do
ga
gi
gu
ge
go

b
b
b
b
b
d
d
d
g
g
g
g
g

/b/ and // (Voiced, Stop)
a
i
u
e
o
a
e
o
a
i
u
e
o

2,749,654
1,177,824
2,758,994
1,591,698
1,104,998
9,953,427
7,744,822
5,306,817
11,996,376
2,009,223
1,210,586
2,328,945
2,549,499

10,011
5,569
9,263
3,769
5,317
17,622
5,965
12,15817,737
6,249
8,951
6,422
7,088

44
45
46
47
48

CV
CV
CV
CV
CV

za
zi
zu
ze
zo

z
z
z
z
z

/z/ (Voiced, Fricative)
a
i
u
e
o

1,384,993
6,550,231
1,644,763
1,646,454
936,779

5,736
15,529
8,670
3,024
3,125

49
50
51
52
53
54
55
56

CV
CV
CV
CV
CV
CV
CV
CV

ma
mi
mu
me
mo
na
ni
nu

m
m
m
m
m
n
n
n

/m/ and /n/ (Voiced, Nasal)
a
i
u
e
o
a
i
u

6,289,027
3,972,466
2,577,386
4,118,162
6,791,877
10,498,607
14,757,618
411,356

28,364
21,4598,694
9,174
12,18018,207
10,038
2,034

545

546

TAMAOKA AND MAKIOKAAPPENDIX A (Continued)

57
58

Phonemic
Combination
CV
CV

Mora
ne
no

Cons/Semi
n
n

59
60
61
62
63

CV
CV
CV
CV
CV

ra
ri
ru
re
ro

r
r
r
r
r

64
65
66
67

SV
SV
SV
SV

ja
ju
jo
wa

j
j
j
w

68
69
70
71
72
73
74
75
76

CSV
CSV
CSV
CSV
CSV
CSV
CSV
CSV
CSV

77
78
79
80
81
82

Token Frequency
2,771,906
19,326,674

Type Frequency
6,260
14,413/r/ (Voiced, Liquid)
a
i
u
e
o

6,947,107
6,116,529
28,899,891
5,777,889
2,927,552

20,44225,431
23,656
9,566
13,925/w/ and /j/ (Voiced, Semivowel)auoa3,432,278
1,620,066
4,484,240
3,777,201

13,622
10,491
5,464
13,922

pja
pju
pjo
tja
tju
tjo
kja
kju
kjo

/pj/, /tj/, and /kj/ (Voiceless, Stop)
pj
a
pj
u
pj
o
tj
a
tj
u
tj
o
kj
a
kj
u
kj
o

95
29,907125,380
199,251
995,900
2,206,487
166,750929,206
2,721,853

9
147
82
1,216
1,898
9,007
551
1,814
4,139

CSV
CSV
CSV
CSV
CSV
CSV

sja
sju
sjo
hja
hju
hjo

/sj/ and /hj/ (Voiceless, Fricative)
sj
a
sj
u
sj
o
hj
a
hj
u
hj
o

2,138,138
2,858,438
3,740,881
53,284
3,304
577,939

3,208
5,175
8,688
170
69
700

83
84
85
86
87
88

CSV
CSV
CSV
CSV
CSV
CSV

bja
bju
bjo
gja
gju
gjo

bj
bj
bj
gj
gj
gj

/bj/ and /j/ (Voiced, Stop)
a
u
o
a
u
o

511
16,016
162,751
59,424
15,343937,044

45
83
504
207
117
2,084

89
90
91

CSV
CSV
CSV

zja
zju
zjo

zj
zj
zj

/zj/ (Voiced, Fricative)auo188,263
1,482,387
2,041,928

1,166
3,623
4,929

92
93
94
95
96
97

CSV
CSV
CSV
CSV
CSV
CSV

mja
mju
mjo
nja
nju
njo

mj
mj
mj
nj
nj
nj

/mj/ and /nj/ (Voiced, Nasal)
a
u
o
a
u
o

14,646
15,49433,782
3,087
446,886
10,406

113
201
400
69
738
175

98
99
100

CSV
CSV
CSV

rja
rju
rjo

rj
rj
rj

/rj/ (Voiced, Liquid)auo50,769214,108
1,541,224

183
1,122
2,442

101

N

N

–

// (Voiced, Nasal)–

35,719,268

81,463R// (Long Vowel Including Two Same Vowels Simply Continued)
R––
3,607,169

23,598

102
103

Q

Q

–

Vowel
e
o

Katakana/Q/ (Geminate)–

7,858,931

14,435FREQUENCY OF OCCURRENCE FOR JAPANESE PHONOLOGICAL UNITSAPPENDIX B
Frequency Counts of 33 Additional Morae (or Kana) Used for Describing Alphabetic Loanwords
Phonemic
Combination
MoraCons/Semi
Vowel
Katakana
Token Frequency
Type Frequency
102
CSV
sje
sj
e
14,924
149
103
CSV
cje
cj
e
37,633
269
104
CV
ca
c
a
2,465
43
105
CV
ce
c
e
4,802
38
106
CV
co
c
o
675
14
107
CV
ti
t
i
66,313
1,205
108
CV
fa
f
a
60,484
681
109
CV
fi
f
i
50,615
474
110
CV
fe
f
e
16,129
346
111
CV
fo
f
o
31,399
408
112
CSV
zje
zj
e
30,738
255
113
CV
di
d
i
65,994
947
114
CSV
dju
dj
u
8,344
65
115
SV
je
j
e
20
7
116
SV
wi
w
i
12,605
170
117
SV
we
w
e
25,909
226
118
SV
wo
w
o
7,747
109
119
CSV
kwa
kw
a
21
2
120
CSV
kwi
kw
i
20
6
121
CSV
kwe
kw
e
2
1
122
CSV
kwo
kw
o
85
10
123
CV
ci
c
i
13,067
15
124
CV
tu
t
u
1,854
78
125
CSV
gwa
gw
a
25
5
126
CV
du
d
u
1,542
55
127
CSV
vwa
vw
a
641
80
128
CSV
vwi
vw
i
733
81
129
CV
vu
v
u
283
29
130
CSV
vwe
vw
e
311
38
131
CSV
vwo
vw
o
66
15
132
CSV
tju
tj
u
72
8
133
CSV
fju
fj
u
206
7
134
CSV
vju
vj
u
34
4
Note—The 33 additional kana are listed on the basis of the Cabinet Announcement of the Government of Japan (1991). The
frequencies of the 33 kana were counted using words described in katakana. The phonemic expressions of these kana werebasically adapted from Matsuzaki (1993), with a few exceptions, such as /v/ for
,
, ,
, and
.
(Manuscript received July 23, 2003;
revision accepted for publication June 4, 2004.)

547