A Comparison of Phonology-Orthography Consistency and L1-Absent Phonemes in Junior High School English Language Textbooks in Japan and South Korea ()
1. Introduction
The intricate relationship between letters, sounds, and graphophonemic correspon- dence in English presents a significant challenge, particularly for those learning English as a foreign language (EFL). In English, a single letter can represent multiple sounds, and conversely, a single sound can be represented by multiple letters, indicating inconsistencies in orthography and phonology (Lim, O’Brien, & Onni, 2024).
According to Narita (2009), although the relationship between sound-letter and letter-sound correspondences in English is highly complex, many of these correspondences exhibit discernible patterns. For instance, the English phoneme /e/ is represented by the grapheme <e> in 96% of instances. Similarly, the phoneme /ʌ/ is represented by the grapheme <u> in 91% of cases (e.g., but), while the grapheme <o> accounts for 7% of occurrences (e.g., love). In contrast, the English graphemes <ough> (e.g., enough) and <oo> (e.g., blood) are rarely associated with the phoneme /ʌ/, indicating an irregular phoneme-grapheme relationship.
Some alphabetic languages such as Finnish and Spanish exhibit an almost one-to-one correspondence between letters and sounds. Consequently, for learners of English who have a different first language (L1), acquiring the complex letter-sound relationships found in English, whether through letter-to-sound conversion (decoding) or sound-to-letter conversion (encoding), is likely to present a significant challenge even in the earlier stages of learning.
Another factor that complicates EFL learners’ acquisition of English is the absence of English phonemes in their L1 (Ohata, 2004). To illustrate, the Japanese language has only 22 phonemes (5 vowels and 17 consonants), whereas English has 44 phonemes (20 vowels and 24 consonants), which is double the number (Kavanagh, 2007). This discrepancy signifies that English phonemes, particularly vowels, are approximately three times more unfamiliar to Japanese learners of English, while consonants are approximately 1.4 times more unfamiliar to them (see Table 1).
Similarly, the Korean language has 26 phonemes, including 7 vowels and 19 consonants (Uchida & Takagi, 2018). South Korean learners of English encounter approximately three times as many unfamiliar vowels, which can result in phonological errors such as the substitution of unfamiliar phonemes with more familiar ones (Kania & Ardi, 2022).
Both Japanese and South Korean learners of English must not only grasp the complex relationship between English letters and sounds, but also acquire a range of previously unfamiliar phonemes. However, Japanese learners of English face a greater challenge in this area, as they are required to master approximately 1.3 times more phonemes (24 phonemes) than their South Korean counterparts (19 phonemes).
The analysis of English language textbooks is one of the most frequently addressed topics in EFL research. A Google Scholar search for the keyword “English language textbook” yielded 17,800 and 17,200 results, respectively, when the search was and was not restricted to those published after 2020, indicating considerable scholarly attention to the theme.
Some studies have compared Japanese and South Korean English language textbooks (Takeda, Choi, Mochizuki, & Watanabe, 2006; Ookawa, 2017). For example, Takeda, Choi, Mochizuki, and Watanabe (2006) conducted a comparative analysis of high school English language textbooks in Japan and South Korea. Their study encompassed a range of aspects, including the quantity and difficulty level of textbooks, structural elements, types of activities and tasks, and cultural content. The findings revealed that English language textbooks in Korea contained approximately three times the number of passages, particularly within the reading section, compared to those in Japan. Ookawa (2017) conducted a comparative analysis of English language textbooks for Japanese and South Korean high school students, and found that English language textbooks in Korea incorporated a greater number of activities and tasks encompassing all four skills (reading, writing, speaking, and listening) within each chapter than did their Japanese counterparts.
Interestingly, prior studies on textbooks have focused relatively little on difficulty levels with regards to the relationship between English sounds and letters, especially phonemes absent in L1 (Ichiyama, 2018; Mukai, Järvikivi, & Tucker, 2023). Therefore, this study aims to compare the difficulty levels of English used in the reading sections of Japanese and South Korean junior high school English language textbooks in terms of the relationship between English sounds and letters, with a particular focus on phonemes that do not exist in L1.
Based on previous research findings (Takeda, Choi, Mochizuki, & Watanabe, 2006; Ookawa, 2017), this study hypothesized that Korean English language textbooks would demonstrate a higher standard compared to their Japanese counterparts in all respects, including the frequencies of phonemes and their relationships to graphemes.
The findings of this study will be beneficial for learners and educators whose L1 is a language with phonemes different from those in English to recognize the importance of teaching and learning the complex sound-letter relationship in the English language.
Table 1. Phonemes of the English, Japanese, and Korean Languages.
|
Vowels |
Consonants |
Total |
| Phonemes |
n |
Phonemes |
n |
n |
| Japanese |
/e//ɑ//i://u://ɑ://ei//ai/ |
8 |
/p// t// k// b// d// g// s/ /h// m// n// l// r/ |
12 |
20 |
| Non-Japanese |
/ɪ//æ//ʊ//ɔ://ʌ//ə//ə://ɔɪ//aʊ//oʊ//ɪər//eər//ʊər/ |
13 |
/ʧ// ʤ// f// θ// ʃ// v/ /ð/ / ʒ// ŋ// w// j/ |
11 |
24 |
| Korean |
/e//ɑ//ɔ//ə//i://u://ɑ://ə://ei//ai//ɪə//eə/ |
12 |
/p// t// k// b// d// s/ /h// m// n// ŋ// l// r/ |
13 |
25 |
| Non-Korean |
/ɪ//æ//ʊ//ʌ//ɔɪ//aʊ//oʊ//ʊər/ |
8 |
/g// ʧ// ʤ// f// θ// ʃ// v/ / ð// ʒ// w// j/ |
11 |
19 |
n: number.
2. Materials and Methods
2.1. Materials
This study examined English language textbooks used by third-year junior high school students in Japan and South Korea, a research focus that has been largely neglected in prior studies within the field of EFL. The rationale for selecting textbooks for third-year junior high school students is grounded in the expectation that, at this stage of education, students should develop a deeper understanding of the subject matter and engage with a prescribed volume of reading material. Notably, all Japanese junior high school students, except for those in some private institutions, are required to take and pass a senior high school entrance examination to secure admission. Given that English is a mandatory subject on this examination, it can be reasonably inferred that the texts are chosen to support the progressive development of English reading comprehension skills. Furthermore, in contrast to Japan, in South Korea, English is offered as an elective subject beginning in the second year of high school. Therefore, it is considered appropriate to utilize textbooks from the third year of junior high school, where English remains a compulsory subject (Chung & Choi, 2016). Six textbooks comprising the three most widely used texts in each country were selected. Each textbook consists of multiple units, each comprising various sections. These sections explicitly delineate the specific skills—reading, writing, speaking, and listening—that constitute the primary focus of each unit. Therefore, this study concentrated on the English texts within the specifically designated reading sections. Table 2 lists the titles and publishers of the selected textbooks.
2.2. Procedure
The texts were entered into an Excel spreadsheet for analyzing the various linguistic elements, including the total number of words, sentences, words per sentence, phonemes, phonemes present and absent in L1, and the regularity of graphemes corresponding to vowel phonemes absent in L1.
Cobb’s (2000) Lextutor software was used to evaluate the lexical difficulty of the textbooks. The software systematically categorized the words based on their frequency distribution, organizing them into four distinct categories: the first thousand (K1) and second thousand (K2) frequency bands, the academic word list (AWL), and an “off list” category (Off) comprising words that did not fall within these established frequency bands. This categorization allowed for a comprehensive analysis of the lexical challenges posed by the selected vocabulary.
In addition to lexical analysis, the software toPhonetics (2013) was used to detect and analyze the phonemes within words.
2.3. Analysis
One-way analysis of variance (ANOVA) was used to examine potential differences in the number of words, sentences, words per sentence, difficulty level, and phonemes between the three English language textbooks from Japan and South Korea, respectively. Additionally, a t-test was conducted to assess differences in the number of words, sentences, words per sentence, and phonemes between the Japanese and South Korean English language textbooks. A chi-square test was conducted to investigate differences in word difficulty, L1-absent phonemes, and phoneme-grapheme correspondence in non-L1 vowel phonemes in the Japanese and South Korean English language textbooks.
Table 2. Titles and publishers of the six textbooks.
|
Title |
Publisher |
Country |
| 1 |
New Horizon |
Tokyo Shoseki |
Japan |
| 2 |
New crown |
Sanseido |
Japan |
| 3 |
Sunshine |
Kiryudo |
Japan |
| 4 |
Middle School English 3 |
Chunjae Education |
South Korea |
| 5 |
Middle School English 3 |
Visang Education |
South Korea |
| 6 |
Middle School English 3 |
Neungyule Education |
South Korea |
3. Results
The vocabulary of the reading sections in the six English language textbooks were analyzed according to Ichiyama’s (2018) framework, focusing on the following five aspects:
Length (word, sentence, words per sentence).
Lexical difficulty (K1, K2, AWL, Off list).
Frequencies of 44 phonemes (20 vowels, 24 consonants).
L1 phoneme correspondence (present vs. absent).
Graphemes corresponding to non-L1 vowel phonemes (regular vs. irregular).
3.1. Length
Table 3 shows the number of words, sentences, and words per sentence in the Japanese and South Korean English language textbooks. In this section, we first examine whether there are significant differences between the three English language textbooks from Japan and South Korea and then examine whether there are differences in linguistic features between the Japanese and South Korean English language textbooks.
3.1.1. Comparison between Japanese English Language Textbooks
An ANOVA was performed to assess differences between the three English language textbooks used in Japanese junior high schools in terms of linguistic features, including the number of words, number of sentences, and words per sentence. The results indicated no statistically significant differences across the three textbooks, F (2, 6) = 5.1, p = 0.98. As the p-value exceeded the significance threshold, no further post hoc analysis was conducted, indicating that the three textbooks contain similar linguistic features.
3.1.2. Comparison between Korean English Language Textbooks
Similarly, an ANOVA was performed to examine differences in linguistic features across the three English language textbooks used in South Korean junior high schools. The analysis revealed no statistically significant differences between the textbooks, F (2, 6) = 5.1, p = 0.99, suggesting that the three textbooks had similar linguistic characteristics.
3.1.3. Comparison between Japanese and Korean Textbooks
To assess whether the difference in the mean number of words in the reading comprehension sections of the English language textbooks from Japan (M = 302.2, SD = 88.1) and South Korea (M = 398.9, SD = 45.8) was statistically significant, a two-tailed t-test was performed at a 5% significance level. The results indicated a significant difference, t (45) = −8.2, p < 0.01, confirming that the mean number of words per sentence in the South Korean English language textbooks was significantly higher than that in the Japanese English language textbooks.
A two-tailed t-test was used to assess the statistical significance of the difference in the mean number of sentences within the reading comprehension sections of the Japanese (M = 33.9, SD = 11.1) and South Korean (M = 41.3, SD = 38) English language textbooks at the 5% significance level, t (47) = −3.1, p < 0.01, indicating a statistically significant mean difference. These findings suggest that the South Korean English language textbooks featured a significantly higher mean number of sentences than did the Japanese English language textbooks.
The independent samples t-test revealed that there was no statistically significant difference in the mean number of words per sentence between the Japanese (M = 9.1, SD = 1.6) and South Korean (M = 9.8, SD = 1.8) English language textbooks, t (46) = −1.6, p = 0.11.
Table 3. Word length, sentence length, and words per sentence in the six English language textbooks.
|
Words |
Sentences |
Words per sentences |
| JT average |
302 |
34 |
9.1 |
| JT1 |
313 |
34 |
9.3 |
| JT2 |
332 |
39 |
8.8 |
| JT3 |
263 |
29 |
9.1 |
| KT average |
399 |
41 |
9.8 |
| KT1 |
393 |
42 |
9.9 |
| KT2 |
412 |
41 |
10 |
| KT2 |
392 |
41 |
9.8 |
JT: Japanese English language textbook, KT: South Korean English language textbook.
3.2. Lexical Difficulty
This section compares the vocabulary levels of the three English language textbooks for third-year junior high school students in Japan and South Korea using the three English language textbooks (see Table 4). After initially examining potential significant differences between the three English language textbooks from Japan and South Korea respectively, we analyzed the language-level differences between the Japanese and South Korean English language textbooks.
3.2.1. Comparison between Japanese English Language Textbooks
A one-way ANOVA was conducted to compare the difficulty of the vocabularies in the three English language textbooks used by Japanese third-year junior high school students. The results showed no significant differences in vocabulary levels between the three textbooks, indicating uniformity in these measures, F (2, 9) = 4.26, p = 0.98.
3.2.2. Comparison between Korean English Language Textbooks
Similarly, an ANOVA was performed to examine the difficulty of the vocabularies in the three English language textbooks used by South Korean third-year junior high school students. No statistically significant differences were found between the textbooks in terms of vocabulary level, F(2, 9) = 0.45, p = 0.99. This suggests that the textbooks have similar textual characteristics.
3.2.3. Comparison between Japanese and Korean Textbooks
We conducted a chi-square test of independence and found significant differences between the conditions, χ2(3) = 101.4, N = 6632, p = 0.017. Residual analysis indicated that English language textbooks in Japan preferred words from the Off list (p = 0.002) over English language textbooks in South Korea. Analyzing the vocabulary levels of the six textbooks revealed that the occurrence rates of K1, K2, and AWL words were consistent across both countries. However, the occurrence rate of words not included in these three categories (Off) was slightly higher in Japanese English language textbooks.
Table 4. Lexical complexity levels in English language textbooks in Japan and South Korea.
|
K1 |
K2 |
AWL |
Off |
| n |
% |
n |
% |
n |
% |
n |
% |
| JT average |
2784 |
83.4 |
189.3 |
5.7 |
61.3 |
1.8 |
303.7 |
9.1 |
| JT1 |
2453 |
83.8 |
134 |
4.6 |
73 |
2.5 |
268 |
9.2 |
| JT2 |
2818 |
83.9 |
230 |
6.8 |
72 |
2.1 |
240 |
7.1 |
| JT3 |
3,081 |
82.7 |
204 |
5.5 |
39 |
1 |
403 |
10.8 |
| KT average |
2802.3 |
85.1 |
192 |
5.8 |
68 |
2.1 |
230.7 |
7.0 |
| KT1 |
2839 |
85.5 |
190 |
5.7 |
100 |
3 |
191 |
5.8 |
| KT2 |
2823 |
84.7 |
207 |
6.2 |
55 |
1.7 |
246 |
7.4 |
| KT2 |
2745 |
85 |
179 |
5.5 |
49 |
1.5 |
255 |
7.9 |
K1: The most frequent 1000 words; K2: The second most frequent 1000 words; AWL: Academic words; Off: Words not listed in K1, K2, and AWL; JT: Japanese English language textbook; KT: Korean English language textbook.
3.3. Frequencies of 44 Phonemes
Table 5 and Table 6 present the frequency of phoneme occurrence in the reading sections of the Japanese and South Korean English language textbooks, categorized by vowels and consonants. In this section, we first examine whether there are significant differences between the three English language textbooks from Japan and South Korea, and then examine whether there are differences in phonemes between the Japanese and South Korean English language textbooks.
Table 5. Frequency of phoneme occurrence in English language textbooks used in Japan.
|
|
JT1 |
JT2 |
JT3 |
JT average |
| Vowel |
ɪ |
899 |
945 |
958 |
934 |
| e |
255 |
240 |
310 |
268 |
| æ |
177 |
192 |
216 |
195 |
| ʊ |
70 |
94 |
134 |
99 |
| ɔ: |
61 |
82 |
108 |
84 |
| ɑ |
101 |
125 |
125 |
117 |
| ʌ |
142 |
187 |
140 |
156 |
| ə |
901 |
1036 |
1116 |
1018 |
| i: |
158 |
161 |
201 |
173 |
| u: |
116 |
96 |
134 |
115 |
| ɑ: |
38 |
30 |
31 |
33 |
| ə: |
430 |
386 |
380 |
399 |
| ei |
210 |
181 |
168 |
186 |
| ai |
306 |
277 |
206 |
263 |
| ɔɪ |
7 |
8 |
7 |
7 |
| aʊ |
88 |
110 |
76 |
91 |
| oʊ |
198 |
144 |
131 |
158 |
| ɪər |
22 |
22 |
25 |
23 |
| eər |
35 |
28 |
44 |
36 |
| ʊər |
9 |
6 |
4 |
6 |
| Consonant |
p |
258 |
226 |
255 |
739 |
| t |
696 |
771 |
884 |
2351 |
| k |
313 |
358 |
392 |
1063 |
| b |
170 |
170 |
243 |
583 |
| d |
470 |
537 |
545 |
1552 |
| g |
103 |
127 |
124 |
354 |
| ʧ |
67 |
58 |
87 |
212 |
| ʤ |
67 |
103 |
81 |
251 |
| f |
196 |
228 |
214 |
638 |
| Consonant |
θ |
36 |
47 |
41 |
124 |
| s |
500 |
487 |
663 |
1650 |
| ʃ |
67 |
127 |
80 |
274 |
| h |
144 |
158 |
225 |
527 |
| v |
182 |
188 |
187 |
557 |
| ð |
286 |
338 |
393 |
1017 |
| ｚ |
360 |
385 |
372 |
1117 |
| ʒ |
3 |
6 |
3 |
12 |
| m |
316 |
381 |
346 |
1043 |
| n |
712 |
829 |
842 |
2383 |
| ŋ |
98 |
134 |
107 |
339 |
| l |
467 |
510 |
571 |
1548 |
| w |
247 |
250 |
275 |
772 |
| r |
228 |
255 |
266 |
749 |
| j |
126 |
125 |
165 |
416 |
JT: Japanese English language.
Table 6. Frequency of phoneme occurrence in English language textbooks used in South Korea.
|
|
KT1 |
KT2 |
KT3 |
KT average |
| Vowel |
ɪ |
887 |
925 |
824 |
879 |
| e |
276 |
229 |
230 |
245 |
| æ |
201 |
218 |
172 |
197 |
| ʊ |
95 |
62 |
135 |
97 |
| ɔ |
86 |
72 |
70 |
76 |
| ɑ |
120 |
107 |
117 |
115 |
| ʌ |
146 |
159 |
159 |
155 |
| ə |
993 |
1015 |
912 |
973 |
| i: |
190 |
120 |
173 |
161 |
| u: |
126 |
126 |
106 |
119 |
| ɑ: |
82 |
118 |
113 |
104 |
| ə: |
348 |
395 |
411 |
385 |
| ei |
151 |
216 |
223 |
197 |
| ai |
253 |
266 |
280 |
266 |
| ɔɪ |
18 |
15 |
18 |
17 |
| aʊ |
75 |
60 |
110 |
82 |
| oʊ |
124 |
101 |
162 |
129 |
| Vowel |
ɪə |
30 |
26 |
12 |
23 |
| eə |
39 |
35 |
26 |
33 |
| ʊər |
5 |
6 |
9 |
7 |
| Consonant |
p |
282 |
259 |
245 |
786 |
| t |
852 |
842 |
757 |
2451 |
| k |
408 |
342 |
319 |
1069 |
| b |
196 |
215 |
205 |
616 |
| d |
506 |
471 |
476 |
1453 |
| g |
107 |
98 |
89 |
294 |
| ʧ |
71 |
66 |
58 |
195 |
| ʤ |
49 |
47 |
65 |
161 |
| f |
232 |
243 |
223 |
698 |
| θ |
65 |
50 |
48 |
163 |
| s |
555 |
553 |
495 |
1603 |
| ʃ |
81 |
77 |
73 |
231 |
| h |
203 |
223 |
184 |
610 |
| v |
226 |
188 |
151 |
565 |
| ð |
354 |
375 |
325 |
1054 |
| z |
380 |
381 |
330 |
1091 |
| ʒ |
5 |
3 |
4 |
12 |
| m |
365 |
383 |
302 |
1050 |
| n |
757 |
716 |
704 |
2177 |
| ŋ |
162 |
123 |
115 |
400 |
| l |
478 |
443 |
420 |
1341 |
| w |
273 |
267 |
274 |
814 |
| r |
276 |
224 |
246 |
746 |
| j |
121 |
111 |
123 |
355 |
KT: South Korean English language textbook.
3.3.1. Comparison between Japanese English Language Textbooks
A one-way ANOVA was performed to assess differences in the phonemes between the three English language textbooks used in Japanese junior high schools. The results indicated no statistically significant differences across the three textbooks, F (2, 78) = 3.1, p = 0.99. As the p-value exceeded the significance threshold, no further post hoc analysis was conducted, indicating that the three textbooks contained similar linguistic features.
3.3.2. Comparison between Korean English Language Textbooks
Additionally, an ANOVA examining phoneme differences between the three English language textbooks used in South Korean junior high schools found no statistically significant differences between the textbooks, F (2, 78) = 3.1, p = 0.99, suggesting that the three textbooks have similar linguistic characteristics.
3.3.3. Comparison between Japanese and Korean Textbooks
An independent samples t-test revealed no statistically significant difference in phoneme occurrence between the Japanese (M = 219.3, SD = 226.4) and South Korean English textbooks (M = 213.8, SD = 217.8), t (100) = −0.1, p = 0.9.
3.4. L1 Phoneme Correspondence
A comparative analysis of the phonemes in the Japanese and South Korean English language textbooks, with particular attention to the phonemes present or absent in Japanese and Korean (see Table 7). Only 68.3% of the phonemes found in the Japanese English language textbooks corresponded to those in Japanese, whereas 74.7% of the phonemes in the South Korean English language textbooks were shared with Korean. Notably, approximately 11.1% of the phonemes in the South Korean English language textbooks were associated with vowels present in Korean, in contrast to a mere 4.7% correspondence of phonemes to Japanese vowels in Japanese English language textbooks.
Comparison between Japanese and Korean Textbooks
A chi-square test revealed significant differences between the conditions, χ2(1) = 362.1, N = 13,922, p < 0.00. Subsequent residual analysis demonstrated a statistically significant preference for non-L1 phonemes in Japanese English language textbooks compared to their South Korean counterparts (p < 0.00).
The findings indicate that, while the South Korean English language textbooks exhibited a greater lexical richness compared to their Japanese counterparts, the number of instances of phonemes absent from the learners’ L1 was comparatively lower. Conversely, the Japanese English language textbooks displayed a more limited vocabulary compared to their South Korean counterparts, yet featured a higher frequency of phonemes absent from the learners’ L1s.
Table 7. Phonemes present and absent in Japanese and Korean.
|
Present in L1 |
Absent in L1 |
|
Vowel |
Consonant |
Vowel |
Consonant |
|
n |
% |
n |
% |
n |
% |
n |
% |
| JT |
1157 |
4.7 |
15,659 |
63.6 |
3206 |
13 |
4612 |
18.7 |
| KT |
2697 |
11.1 |
15,393 |
63.6 |
1562 |
6.5 |
4542 |
18.8 |
JT: Japanese English language textbook; KT: Korean English language textbook.
3.5. Graphemes Corresponding to Non-L1 Vowel Phonemes
This section provides a comparative analysis of the graphemes corresponding to non-L1 vowel phonemes. Vowel phonemes that do not exist in L1 (six phonemes in Japanese and four phonemes in Korean) were selected from the top ten most frequently occurring vowel phonemes. The frequencies and percentages of the graphemes corresponding to each phoneme were subsequently calculated. Following the methodology proposed by Narita (2009), graphemes that occurred at a rate of 5% or higher were classified as graphemes possessing regular phoneme-grapheme relationships, whereas those with a percentage below 5% were categorized as irregular graphemes (see Table 8 and Table 9).
Many irregular phoneme-grapheme correspondences occur in Japanese English language textbooks, particularly in relation to the phonemes /ə/ and /ə:/, which are not present in Japanese. For example, the phoneme /ə:/ is represented by the grapheme <er> in 54% of instances; <ur>, 24%; <ir>, 11%; and <our>, 2% (Narita, 2009).
In Japanese English language textbooks, words such as “hour” are classified as K1 words—those considered fundamental yet possessing rare phoneme-grapheme relationships—and appear more than ten times. In contrast, South Korean English language textbooks exhibit a relatively frequent occurrence of irregular graphemes, primarily with the phoneme /ɪ/. It is exceedingly rare for the phoneme /ɪ/ to appear in the graphemes <ie> in “movie” or <a> in “garbage,” as seen in South Korean English language textbooks. Nevertheless, with the exception of the phoneme /ɪ/, vocabularies with irregular sound-letter relationships in non-L1 vowel phonemes are seldom employed.
Comparison between Japanese and Korean Textbooks
The chi-square test conducted in this study found significant differences between the conditions, χ2(3) = 168.6, N = 10213, p < 0.00. Residual analysis further revealed that Japanese English language textbooks exhibited a statistically significant preference for phonemes with irregular graphemes (p < 0.00) compared to South Korean English language textbooks.
The findings indicate that South Korean English language textbooks use a considerable number of non-native phonemes that adhere to established regular phoneme-grapheme relationships, whereas Japanese English language textbooks use a significant proportion of relatively basic-level vocabularies that possess non-L1 phonemes that deviate from conventional regular phoneme-grapheme relationships.
Table 8. Frequency of graphemes corresponding to non-L1 vowel phonemes (regular vs. irregular) in Japanese English language textbooks.
|
|
K1 |
K2 |
AWL |
Off |
|
|
n |
% |
n |
% |
n |
% |
n |
% |
| ə |
Irregular G |
204 |
9 |
9 |
10 |
10 |
18 |
22 |
7 |
| Regular G |
2087 |
91 |
82 |
90 |
46 |
82 |
275 |
93 |
| ɪ |
Irregular G |
33 |
3 |
1 |
1 |
0 |
0 |
0 |
0 |
| Regular G |
1112 |
97 |
149 |
99 |
95 |
100 |
256 |
100 |
| ə: |
Irregular G |
283 |
42 |
20 |
32 |
7 |
16 |
16 |
23 |
| Regular G |
389 |
58 |
43 |
68 |
38 |
84 |
53 |
77 |
| æ |
Irregular G |
2 |
1 |
0 |
0 |
0 |
0 |
0 |
0 |
| Regular G |
225 |
99 |
69 |
100 |
6 |
100 |
182 |
100 |
| oʊ |
Irregular G |
6 |
2 |
0 |
0 |
0 |
0 |
0 |
0 |
| Regular G |
248 |
98 |
34 |
100 |
12 |
100 |
211 |
100 |
| ʌ |
Irregular G |
30 |
6 |
0 |
0 |
0 |
0 |
0 |
0 |
| Regular G |
385 |
94 |
55 |
100 |
12 |
100 |
27 |
100 |
G: Grapheme; K1: The most frequent 1000 words; K2: The second most frequent 1000 words; AWL: Academic words; Off: Words not listed in K1, K2, and AWL.
Table 9. Frequency of graphemes corresponding to non-L1 vowel phonemes (regular vs. irregular) in South Korean English language textbooks.
|
|
K1 |
K2 |
AWL |
Off |
|
|
n |
% |
n |
% |
n |
% |
n |
% |
| ɪ |
Irregular G |
18 |
1 |
6 |
4 |
0 |
0 |
20 |
12 |
| Regular G |
1741 |
99 |
143 |
96 |
88 |
100 |
148 |
88 |
| æ |
Irregular G |
22 |
8 |
1 |
2 |
0 |
0 |
0 |
0 |
| Regular G |
241 |
92 |
63 |
98 |
8 |
100 |
100 |
100 |
| oʊ |
Irregular G |
12 |
3 |
2 |
4 |
0 |
0 |
0 |
0 |
| Regular G |
368 |
97 |
49 |
96 |
6 |
100 |
25 |
100 |
| ʌ |
Irregular G |
7 |
2 |
1 |
3 |
0 |
0 |
0 |
0 |
| Regular G |
288 |
98 |
35 |
97 |
17 |
100 |
72 |
100 |
G: grapheme; K1: The most frequent 1 - 1000 words; K2: The 1001 - 2000 most frequent words; AWL: Academic word; Off: Words not listed in K1, K2, and AWL.
4. Discussion
This study aimed to evaluate the phonology-orthography consistency and phonemes absent in L1 and their relationships to the graphemes of Japanese and South Korean English language textbooks to identify potential differences. Regarding the length of the reading sections in English language textbooks, we initially hypothesized that South Korean English language textbooks would surpass Japanese English textbooks in terms of words, sentences, and words per sentence. The hypothesis that South Korean English language textbooks would use longer sentences was supported by the findings related to the number of words and sentences. However, no significant difference was observed in the number of words per sentence, which suggests that lengthy sentences have become less common in South Korean English language textbooks, potentially in response to critiques emphasizing the need to foster communicative competence and shift away from translation-focused teaching methods (Rose, 2023).
Interestingly, there were no significant differences in the frequencies of vocabulary items classified as K1, K2, and AWL. Similarly, there were no significant differences in the frequencies of phoneme occurrence for the 44 English phonemes between the Japanese and South Korean English language textbooks, which also challenges the hypothesis that Korean English language textbooks are superior. Consistent with previous findings, it may be posited that the use of lexical complexity is no longer aligned with the educational policy in South Korea, which prioritizes the enhancement of communicative competence (Chung & Choi, 2016).
Furthermore, the results revealed that Japanese junior high school English language textbooks present significant phonemic challenges to learners, particularly because of the high proportion of non-L1 phonemes and the irregular phoneme-grapheme correspondences they entail. Specifically, 31.7% of the phonemes in these textbooks do not exist in the Japanese phonemic inventory, compared to 25% in the South Korean English language textbooks. Additionally, the Japanese English language textbooks included 643 non-L1 vowel phonemes with irregular phoneme-grapheme correspondences, accounting for approximately 10% of the 6734 non-L1 vowel phonemes analyzed. In contrast, the South Korean English language textbooks exhibited a lower rate of such irregularities, with only 3% of the 3481 non-L1 vowel phonemes displaying irregular correspondences. In summary, these findings suggest that Japanese English language textbooks may not sufficiently prioritize the student’s sound-letter relationships or graphophonemic knowledge critical to reading proficiency, potentially making English language acquisition more challenging for Japanese students.
Given these results, it is imperative that English language textbook developers place greater emphasis on the inclusion and treatment of non-L1 phonemes and their corresponding graphemes, especially in contexts where the L1 has a limited phonemic inventory and predominantly regular phoneme-grapheme correspondences, such as in Japan. Such an approach could help mitigate the difficulties learners face, enhancing both their reading proficiency and overall language acquisition. It could also benefit learners and educators in similar linguistic contexts where irregular phoneme-grapheme correspondences in English present significant obstacles to learning.
However, the present findings should be interpreted with caution because of the limited sample size, which may affect their generalizability. Future research should seek to analyze a wider range of textbooks to provide a more comprehensive understanding of these challenges. Additionally, surveys at the primary school level are essential to evaluate the effectiveness of English language materials during the early stages of language learning. Future studies should consider exploring the necessity of explicit instruction on the complex relationship between English phonemes and graphemes in classroom settings to better support learners facing these challenges.
Acknowledgements
This work was supported by JSPS KAKENHI Grant-in-Aid for Scientific Research (C) No. 23K00727. The author is grateful for their support.