39

論文
A Comparative Study on Reading Aloud: Instructions by Text-To-Speech
Synthesis Sounds and a High School Japanese English Teacher
Harumi Kataoka(Graduate School, Kansai University)

Makiko Ito(Osaka Prefectural Kashiwara-higashi High School)

１． INTRODUCTION
The curriculum guidelines (2010) of the Ministry of Education, Culture, Sports, Science andTechnology (MEXT) required Information and Communication Technology (ICT) into
practical use in not only Information lessons, but also each subject lessons. For example, thecurriculum guidelines recommend using audio CDs, DVDs, and computers during foreign
language learning in Japanese elementary school education.
With the advancement of computer software, various styles in foreign language
teaching have been developed since the early 2000s, including Text-To-Speech (TTS)
synthesis technology. TTS refers to digital speech synthesis technology using audio
database of native English speakers. Users can produce TTS synthesized speechsounds automatically by typing English words on their computer keyboards. By using
TTS, teachers can control English speech sounds of (a) the speed, (b) the pause, (c) the
duration, and (d) even choosing TTS speakers. Then they can produce audio English
language learning materials to fit their students’ English proficiency (Kataoka, 2009).
However, there are not enough research results on how to use TTS speech sounds in theclassroom, especially for Japanese high school students. This may be the reason why some
native and non-native English teachers in Japan have negative perceptions about using
TTS synthesized speech sounds during their classroom lessons.
In short, more studies on the use of TTS speech sounds as English language learningmaterials are needed in Japanese English as a Foreign Language (EFL) education.
２． LITERATURE REVIEW
2.1 English Education for EFL Learners
Palmer (1921), a British linguist, who endeavored to build the foundation of English
language education in Japan, insisted that students needed to develop their listening
abilities to understand English speech (pp. 400–401). In order to do so, Hatori (1977, p.74)
recommended that Japanese students need to understand both English spelling andEnglish pronunciation of each English word on an individual basis. He also pointed out thatusing English speech sounds during English lessons would enhance Japanese students’learning motivation. Widdowson (1978, p.57) suggested that four skills—speaking, listening (orHarumi Kataoka, Makiko Ito

40

understanding speech), reading, and writing—are closely related to each other in developing
English acquisition among learners. Kohno (1984) carried out studies which proved that
English speech sounds helped Japanese students understand English. He mentioned that
the Japanese and English languages present differences in their prospective linguistic
structures and pronunciations, and suggested that using English speech sounds as much as
possible during English lessons is of utmost importance. These previous studies haveindicated that audio information and visual information are closely related to understand English.
2.2 Reading Aloud for Japanese EFL learners
Reading aloud, which is called “Ondoku ” in Japanese, is one form of English learning
activities. As suggested by Widdowson concerning four skills, a reading aloud activity would
be practical English learning strategy. There have been some studies on reading aloud inJapanese EFL education.
Watanabe (1988, 2009) conducted a series of comparative studies about reading aloud.
In Watanabe (2009), the participants were categorized into two groups: (a) a reading aloudgroup consisting of 44 second-year Japanese high school students, and (b) a non-reading aloudgroup consisting of 45 second-year Japanese high school students. The results showed thatstudents in the reading aloud group obtained higher test scores and could read andunderstand English sentences faster than the learners in the non-reading aloud group.
Suzuki (1998) conducted a comparative study on reading English sentences aloud duringclassroom lessons in a high school. The results of the English Test of National Center Test for
University Admissions revealed that students who had participated in reading aloudshowed higher test scores than those without reading aloud during their English lessons.
His results suggest that reading aloud during classroom lessons helped promote Japanesehigh school students’ English proficiency.
Ishihara (2002) also conducted comparative research on reading aloud. The participants
were 80 second-year high school students who were divided into two groups. The results ofthe cloze test revealed that 40 students in a reading aloud group marked higher scores than
40 students in non-reading aloud group. The results show that the activity of reading aloudis effective in keeping the memory of the text which they read.
Ikeda and Takeuchi (2003) examined a reading aloud activity conducted by 37 Japanese
university students. They read aloud two kinds of English passages, and were then asked toanswer a cloze test. The findings in this study showed that their reading aloud abilities
were correlated with their English proficiency levels. This suggested that reading short andsimple English sentences aloud would be appropriate for Japanese EFL learners.
Miyasako (2002) investigated a reading aloud activity for 40 high school students during theirEnglish lessons. The results showed that reading aloud improved students’ English
grammar, vocabulary, listening and reading abilities, which implied that this activity.
Reading aloud could help develop high school students’ English proficiency. Miyasako (2007)

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also concluded that reading aloud is an effective English learning method for learners toacquire comprehensive English proficiency.
Kitamura (2007) researched the effect of reading aloud while writing English sentences
repeatedly. A total of 158 Japanese high school students—36 first graders, 59 second
graders, and 63 third graders—participated in the treatment groups. Their regular school
tests and two kinds of tests offered by The Society for Testing English Proficiency (STEP),
Inc. were used to monitor the progress of the participants’ English proficiency. The results
revealed that test scores were positively correlated with the time spent in reading aloud.
These previous studies suggest that reading aloud is an effective learning strategy forJapanese EFL learners to acquire English. Reading aloud activities appear to be effective
for Japanese high school students to learn and memorize English grammatical structures.
2.3 TTS Studies in EFL Education
There have been some research on TTS synthesis technology in EFL education conducted inJapan and overseas. Jones, Berry, and Stevens (2007) conducted an experiment using a
TTS voice. The results showed that both native and non-native speakers of English did not
perceive any differences between TTS speech sounds and human speech sounds. The
findings indicated TTS’s usability for English education in Australia. Chew (2009) reported thata written news text was digitally converted into TTS speech sounds, and used as an English
language test material in Singapore. The finding suggested that the TTS system is useful for
language teachers who want to create audio language learning materials by themselves.
In Japan, Azuma (2008) described how the synthesized English speech generated by
TTS technology could be used, and discussed its introduction in an EFL class in a
Japanese university. He also pointed out that TTS speech sounds differ depending on which
TTS system is used. A study conducted by Yoshida (2008) on an electronic phrasal verb
workbook paired GIF animation together with TTS synthetic speech. The result showed thatthe moving images combined with TTS speech sounds were effective in learning English
among Japanese university students. Kataoka (2009) investigated whether Japanese
undergraduate students and university graduates perceived any differences among three
types of speech sounds: (a) TTS speech sounds, (b) the voice of a native British speaker, and(c) an American speaker. The results concluded that participants did not find any differencesamong the three types of speech sounds. The results indicated that TTS speech sounds havesufficiently high quality to be used as audio materials for Japanese EFL learners.
Hirai and O’ki (2011) examined the quality of TTS synthetic speech by comparing itwith natural human speech. The participants were Japanese university students who
were divided into groups. The results of listening tests showed that TTS speech sounds
were perceived to be almost as natural as human speech by both upper and lower English
proficiency groups, and more students in the lower level group tended to prefer TTS speechsounds.

Harumi Kataoka, Makiko Ito42

３． COMPARISON BETWEEN TWO KINDS OF INSTRUCTIONS
3.1 Purpose
The results of previous TTS studies (Azuma, 2008; Chew, 2009; Hirai and O’ki, 2011;
Jones, Berry, and Stevens, 2007; Kataoka, 2009; Yoshida, 2008) show that there are not somuch difference in voice qualities between TTS speech sounds and English speech sounds byhuman speakers. Because TTS speech sounds are originally created using native English
speakers’ voices. TTS speech sounds appear to be useful for both Japanese EFL learners andEnglish language teachers who really want to create audio language learning materials that
fit their students’ English proficiency level. Unfortunately, some native and Japanese English
teachers have negative perceptions about using TTS speech sounds during theirclassroom lessons, especially high school education in Japan. Most of the English teachers inJapan are not aware of the usability of the TTS systems. Moreover, there are notenough research results to show how TTS can be used in the classroom, especially forJapanese high school students. Therefore, there is a need for more experimental studies of
TTS speech sounds to be conducted for Japanese high school EFL education.
This study investigated whether TTS speech sounds could be used as an English language
learning material for Japanese high school students to learn basic English verbs throughreading aloud activities.
With the purpose of revealing TTS speech sounds as an audio English language learningmaterial, TTS speech sounds were recorded and produced on TTS CDs1 to be used in thepresent study. The research question (RQ) is as follows.
RQ: Is there any significant difference in basic English verb learning between thetwo kinds of reading aloud instructions: (a) a TTS CD style instruction, and (b) a verbal
instruction made by a Japanese English teacher?
If there is no significant difference between the two kinds of instructions in theireffectiveness, the TTS speech sounds in this study would prove to be of high quality andusability as an audio language learning material for Japanese EFL education.
3.2 Review of Ten Basic Verb Words
In order to have the students review basic verb words, which they had learned injunior high schools, following ten basic English sentences cited from Otsuka’s 2
online English language learning materials (2009) were used in this study.
1. Are you a student?
2. Are you from Sapporo?
3. Is this a book?
4. Is Tokyo Disneyland in Tokyo?
5. Is there a pen on the desk?
6. Is Japanese spoken in China?

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7. Are there any good restaurants in your city?
8. Do you have any good restaurants in your city?
9. Do you like English?
10. Do you study English every day?
3.3 TTS System in This Study
The TTS systems are composed of two items: (a) a TTS engine, and (b) a TTS audio
database (Dutoit, 1997). The free TTS software application Balabolka Version 1.9.0.241,
which can be downloaded free of charge, was used as a TTS engine in this study. With
Balabolka, it is possible to define the duration of a short pause to within 1/1000 of asecond. As a TTS audio database, “Mike & Crystal”, who were male and female nameswith synthesized American English voices respectively, and produced by AT & T, was also
installed in a personal computer. These two items were used to produce a TTS system forthis study (Figure 1).

Read Aloud

Pull Down Menu for

Stop Key

Speaker Selection Bar

Pitch Key

VolumeTargetXML Tag, which set

Sentence“Pause”

Figure 1 . A screen of the TTS system.
４． Experiment 1: Speech Analyses
In order to examine the speech quality, two types of speech analyses were conducted: (1)acoustic analyses by a speech analyzer “Praat”, and (2) speech evaluation by raters.
4.1 Results of Acoustic Analyses by a Speech Analyzer “Praat”
Three kinds of speech sound (1) male TTS speech sounds, “Mike”, (2) female TTS speech sounds,“Crystal”, and (3) speech produced by a Japanese female English teacher were used inthis study.

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Figure 2 . A screen image of the speech analyzer “Praat”.
We analyzed duration, the maximum pitch, the minimum pitch, and pitch range to
identify features of speech sounds. Table 1 shows average rate of three kinds ofspeech sounds in this study.
Table 1. The Average Rates of Ten English Sentences by Three Kinds of Speech Sounds

Speech sounds
TTS Male
TTS Female
JET

Duration
1.72 ms
1.98 ms
2.01 ms

Pitch (Max.)
222.37 Hz
239.60 Hz
372.35 Hz

Pitch (Min.)
79.71 Hz125.30 Hz
165.95 Hz

Pitch Range
142.66 Hz
114.30 Hz
206.40 Hz

Note. A Japanese female English teacher’s speech sounds shows “JET”.
As Table 1 indicates a Japanese female English teacher used higher pitch than TTS male/
female speech did. The duration of speech of the Japanese female English teacher was thelongest among three kinds speech sounds, which indicates that her speech rate was theslowest among three speech materials.
4.2 Results of Speech Analyses by Raters
Seven English teachers participated in this study as raters and they were asked tojudge three kinds of speech sounds. The raters consisted of six Japanese English teachers andone assistant language teacher (ALT). They worked at a Japanese high school where theexperiment of this study was conducted. They were asked to listen to the three kinds ofspeech sounds, and then they evaluated three speech samples based on its intelligibility,
comprehensibility, and naturalness as spoken English using the five-point Likert scale style(Takeuchi, 2003, p. 254). Table 2 shows the results judged by seven raters in this study.
The “α ” in table 2 means “Cronbach’s coefficient alpha”. Generally speaking, it is said that
if α value shows over 0.703, there is enough “Inter Rater Reliability”. The α values ofthree kinds of speech sounds in this study showed over 0.90, and revealed there were no
significant difference between seven raters’ scores.

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Synthesis Sounds and a High School Japanese English Teacher

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Table 2. The Results of Three Kinds of Speech Sounds by Seven Raters
Speech sounds
TTS Male
TTS Female
JET

M
3.12
3.38
3.35

SD
0.92
0.88
0.99

α
0.93
0.90
0.96

Note. The “α ” means “Cronbach’s coefficient alpha”, which shows “Inter Rater Reliability”.
Table 2 also showed that TTS female speech sounds gained the highest mean score ofthree speech sounds. This result suggests that TTS female speech sounds had higher speech
quality than a Japanese English teacher’s speech sounds, and thus easy to understand forseven raters.
５． Experiment 2: Basic Verb Words Learning by Reading Aloud
It became evident from the results of experiment 1 that three kinds of speech sounds in thisstudy had enough speech quality. These speech sounds were used as listening materials forreading aloud activities in this study. The results of previous studies on reading aloudactivities (Ikeda and Takeuchi, 2003; Ishihara, 2002; Kitamura, 2007; Miyasako,
2002, 2007; Suzuki, 1998; Watanabe, 1988, 2009) show that this activity is one of theeffective English learning methods for Japanese EFL learners. This is thereason why reading aloud was adopted as a learning method in the current study. Results ofreading aloud were measured with the cloze test styles, as were used by most ofprevious reading aloud studies.
5.1 ParticipantsThis study was conducted in January 2010, and a total of 151 male and female Japanesehigh school students participated in this experiment. The participants were all first year
students from four classes in the same public high school in the Kansai area. They weredivided into two groups according to their regular classes. Group A consisted of 59 students(25 boys and 34 girls), and Group B had 56 students (24 boys and 32 girls). All of them wereborn in Japan and had been studying English for more than three years. None of them had
stayed in an English-speaking country or had any experience of participating in this kind ofexperiment. We ensured that the participants remained anonymous throughout the study.
When all participants took their high school entrance examinations, the average rating points ofschool evaluation, Naishinten , was 4.2 points on a zero-to-ten scale. Therefore, it isspeculated that most of the students in this high school had not mastered basic English
grammar, which was taught in junior high schools, they had to spend a few minutes
reviewing junior high school level English grammar during their senior high school English
lessons.

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5.2 Research Design and Procedure
To investigate the effectiveness of TTS speech sounds as an audio English language
learning material for Japanese high school students to study basic English grammar, thefollowing four phases of the learning process (Table 3) were adopted in this research. The
classroom practice consisted of two reading aloud tasks for six lessons. In the reading aloudtask, students read English sentences silently, while listening to English speech sounds.
After that, students repeated exactly what they heard, while reading the English sentences.
Table 3 shows the timeline for this study.
Table 3. Timeline for This Study
Phase

Day

Activities

English Sentences

1
2

1
2
3
4
5
6
7
8

Pre 10-item Cloze Test
Reading Aloud (1)Reading Aloud (1)Reading Aloud (1)Reading Aloud (2)Reading Aloud (2)Reading Aloud (2)Post 10-item Cloze Test

No. 1 – No. 10
No. 1 – No. 5
No. 1 – No. 5
No. 1 – No. 5
No. 6 – No. 10
No. 6 – No. 10
No. 6 – No. 10
No. 1 – No. 10

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Audio Instruction
Group A ( n = 59)
Group B ( n = 56)
No Audio Instruction No Audio Instruction
TTS CD Sounds
A JET's VoiceTTS CD Sounds
A JET's VoiceTTS CD Sounds
A JET's VoiceA JET's VoiceTTS CD Sounds
A JET's VoiceTTS CD Sounds
A JET's VoiceTTS CD Sounds
No Audio Instruction No Audio Instruction

5.3 Materials
5.3.1 Cloze Test
English sentences in the cloze test were selected from English learning materials
published on the Web page by Otsuka2 (2009). Participants in this study were unable tomaster basic English grammar taught in junior high school level. We decided to use all
English sentences offered by Mr. Otsuka on his Web page, and his permission was obtained touse them in this study. Our aim is for the participants to be able to understand basic
English grammar through reading aloud during classroom practice in this study.
The cloze test styles were used by previous studies on reading aloud activities (Ikeda and
Takeuchi, 2003; Ishihara, 2002; Kitamura, 2007; Miyasako, 2002, 2007; Suzuki, 1998;
Watanabe, 1988, 2009) to check the progress in learners’ English proficiency. In this study,
the same 10-item cloze tests at pre- and post-test were used to check the learning process ofhigh school students (Appendix A). The cloze test in this study was a multiple-choicequestion format. Students were asked to select the best answer among four choices foreach blank, and wrote one answer for each question on their answer sheets. The
maximum number of points in the cloze test was ten. This type of cloze test withfour multiple choice questions is used in the university entrance examination as (1)the first-stage English Test of the National Center Test for University Admissionsand (2) written tests in many private universities. We consider that high school
students in this study should be offered this type of test as much as possible to havelearners get accustomed to this pattern of university entrance examination tests. This

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is why the cloze test with four multiple-choice questions was used in this study.
5.3.2 Materials for Reading Aloud Task: Activity Sheets and TTS CDs
In order to compare the effectiveness of two kinds of instructions, (a) TTS CD style
instruction and (b) instructions using only a Japanese English teacher’s voice, were carriedout with the two groups.
All students in Groups A and B were given either TTS speech sounds or a female
Japanese-English teacher’s voice for each English sentence. During the reading aloud practice,students read English silently while listening to English speech sounds, and then they
repeated English sentences exactly as they had heard. The pauses between the English
sentences were set 5,000 ms (= five seconds) so that they could repeat each English sentence
together in the lessons (Figure 1).
The students in Groups A and B had to learn ten English sentences—1 through 10—in thecloze test (Appendix A) by reading them aloud. It appeared difficult for the students in thetwo groups to learn ten English sentences in one lesson. Therefore, five of the ten English
sentences in the cloze test were learned in three lessons, each under Reading Aloud Tasks(1) and (2) respectively (Appendix B).
According to previous studies (Hatori, 1977; Kohno, 1984; Palmer, 1921), knowing bothpronunciation and meaning of each English and Japanese word would facilitate Japanesehigh school students to understand English. Each group was given “Activity Sheets (1) and(2)” (Appendix B), which were used for the Reading Aloud Tasks (1) and (2) respectively.
In each activity sheet, five English sentences in the cloze test were printed in both English
and Japanese. This way, students could easily understand English sentences by aid of theJapanese sentences. In the cloze test, there were ten English sentences that were
all question sentences. In the reading aloud task, students learned how to answer eachquestion by using activity sheets and reading aloud practice.
The following is a description of the two-step learning process adopted for the reading aloud task:
1. The first step was a “reading and listening” phase. Students were given an “Activity
Sheet”. They read this sheet silently while listening to either TTS CD sounds or a JET’s voice.
2. The second step was a “repeating” phase. After the first step, all students repeated in unison
each English sentence exactly what they had heard, while reading each English sentence on theactivity sheet.

Figure 3 . Procedure of Reading Aloud.

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The number of repetitions is an important issue for English language learners. Tinkham(1993) found that most learners required five to seven repetitions for learning a group of six
paired associates.
To memorize each English sentence in this study, high school students repeated one
English sentence twice for one lesson, and repeated one English sentence six times in total.
In order to exclude the influence of gender, both male and female TTS speech sounds were
given to the students. This reading aloud task was conducted for five minutes during the six
lessons (Table 3).
5.4 Basic Data of the Two Groups
Prior to the experiment, a 10-item cloze test (Appendix A) was administered toGroups A and B to measure their English proficiency. For each correct answer, 1 point in
the cloze test was given, with a total score of 10. The preliminary data is summarized inTable 4.
Table 4. Basic Data of Two Groups

Cloze Test

Group A (n = 59)
M
SD
7.08
1.25

Group B ( n = 56)
M
SD
7.29
1.66

Note. A correct answer was given 1 point, with a total score of 10.
A two-tailed independent t -test4 confirmed that a statistically significant difference did notexist between the results of the two groups (t = -0.74, df = 113, p = 0.46, d = 0.15). Therefore,
they were considered equal in terms of a 10-item cloze test.
The Cronbach’s alpha of the cloze test was 0.38. Judging from this score3, the cloze test
appears to be difficult for the participants, but we hope they were able to learn thegrammatical rule of each English sentence in the cloze test.
5.5 Results and Discussions
5.5.1 Results of a Ten-item Cloze Test
In order to investigate the speech sounds of two kinds of instructions (a) a TTS CD style
instruction and (b) a teacher’s voice instruction, a 10-item cloze test (Appendix A) wasused for the pre-and post-test. The t -test was used to compare the results of a ten-itemcloze test. The p values are generally used to analyze the results of studies. However,the p values change according to the sample size. Effect sizes are the absolute value,
which are not affected by the sample size. Therefore, the effect sizes are needed to reveal thestatistical analyses results (APA, 2009, pp. 32–33; Field, 2009; Mizumoto & Takeuchi, 2008;
Mizumoto, 2009). There are two types of effect sizes5 (1) r and (2) d in a t -test.

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5.5.2 Results of the Reading Aloud Task (1)In order to measure the development of students’ English proficiency using the Reading
Aloud Task (1), students in Groups A and B took a post ten-item cloze test. Then, the answers ofEnglish sentences No. 1 to 5 in a post ten-item cloze test were selected to analyze theReading Aloud Task (1). During the Reading Aloud Task (1), students learned English
sentences No. 1 to 5 in the cloze test (Appendix A, Appendix B). The students in Group A
learned the five English sentences by using an activity sheet (1) (Appendix B) and a TTS CD
for three lessons. The students in Group B learned the five English sentences by using anactivity sheet (1) (Appendix B) and listening to only a teacher’s voice for three lessons.
Table 5 and Figure 4 show the results of items No. 1 to 5 in a post ten-item cloze test.
Table 5. Results of T -Test: Items No. 1 to 5
Group nSounds
M
SD
A
B

59
56

TTS CD
JET's Voice

4.32
4.36

0.65
0.74

Note. One point was granted to each correct
answer, and the total score was 5.

Figure 4 . Comparison between TTS CD andthe teacher’s voice: Items No. 1 to 5.

A two-tailed independent t -test was conducted to compare between a TTS CD (Group A)
and a teacher’s voice (Group B), which were used in the Reading Aloud Task (1).
The results confirmed that a statistically significant difference did not exist (t = -0.27, df =113, p = 0.79, d = 0.06), and the effect size was small. In brief, the result did not show asignificant difference between a TTS CD (Group A) and a JET’s voice (Group B).
5.5.3 Results of the Reading Aloud Task (2)In order to measure the development of students’ English proficiency using the Reading
Aloud Task (2), students in Groups A and B took a post ten-item cloze test. The answers ofEnglish sentences No. 6 to 10 in a post ten-item cloze test were selected to analyze theReading Aloud Task (2). During the Reading Aloud Task (2), students learned English
sentences No. 6 to 10 in the cloze test (Appendixes A and B). The students in Group A learned
the five English sentences by using an activity sheet (2) (Appendix B) and listening to ateacher’s voice, and not a TTS CD, for three lessons. The students in Group B learned the five
English sentences by using an activity sheet (2) (Appendix B) and a TTS CD for three lessons.
Table 6 and Figure 5 show the results of items No. 6 to 10 in ten-item the post cloze test.

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Table 6. Results of T -Test: Items No. 6 to 10
Group nSounds
M
SD
A
B

59
56

JET's VoiceTTS CD

3.64
3.73

1.17
1.14

Note. One point was granted to each correct
answer, and the total score was 5.

Figure 5 . Comparison between TTS CD andthe teacher’s voice: Items No. 6 to 10.

A two-tailed independent t -test was conducted to compare between a teacher’s voice(Group A) and a TTS CD (Group B), which were used in the Reading Aloud Task (2).
The results confirmed that a statistically significant difference did not exist (t = -0.41, df =113, p = 0.68, d = 0.08), and the effect size was small. In brief, the result did not show asignificant difference between a teacher’s voice (Group A) and a TTS CD (Group B).
5.5.4 Results of a Ten-item Cloze Test in Each Group
Table 7 shows the results of a 10-item pre- and post-cloze test in each group. Figure 6graphically shows the test results of Group A and Group B respectively.
Table 7. Result of Dependent T -Test
Pre Test
Group
A
B

n
59
56

M
7.08
7.29

Post Test

SD
1.25
1.66

M
7.97
8.09

SD
1.49
1.44

Note. One point was given to each correct answer, and the total score was 10.

Figure 6 . Comparison of pre- and post-test in Groups A and B.
A two-tailed dependent t -test confirmed that a statistically significant difference existed
between the results of the pre- and post-test in Group A (t = -5.43, df = 58, p = 0.00, r = 0.58),
and a large effect size was found.
A two-tailed dependent t -test also confirmed that a statistically significant difference
existed between the results of a pre- and post-test in Group B (t = -4.20, df = 55, p = 0.00, r =0.49), and a middle effect size was found.
The results in Groups A and B showed that TTS speech sounds have enough audio quality
as much as a JET’s voice, and can be used as audio English language learning materials forA Comparative Study on Reading Aloud: Instructions by Text-To-Speech
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Japanese high school students.
６． SUMMARY AND CONCLUDING REMARKSThis study focuses on the use of TTS synthesized speech sounds introduced in English
grammar instruction in high school education.
There are two limitations in our experiment.
1. The scope of our present study was limited to the question sentence level.
2. This study only compared the usability of TTS speech sounds and a Japanese-English
language teacher’s voice.
Given the research design of this study, some of our conclusions remain tentative. To
overcome this problem, future studies on (1) a variety of sentences and (2) a comparison
between TTS speech sounds and the ALT’s voice, are needed.
Research question (RQ) in this study was “Is there any significant difference in basic
English verb learning between the two kinds of reading aloud instructions: (a) a TTS CD style
instruction, and (b) a verbal instruction made by a Japanese English teacher?”
Our findings revealed two set of results.
First, the results obtained in a pre- and post-cloze test show that a statistically significant
difference existed in Group A and Group B respectively (see section 5.5.4). This suggests that
TTS speech sounds can be used as audio English language learning materials for Japanesehigh school EFL education.
Second, a statistically significant difference did not exist between the two types of
instructions: (a) a TTS CD style instruction, and (b) a JET’s voice instruction (see sections
5.5.2 and 5.5.3).
The results confirm that TTS speech sounds used in this study had enough usability as
speech sounds for Japanese high school EFL education. The difference or gap did not appear
between the TTS speech sounds and the teacher’s voice in this study.
Our results prove the usability of TTS speech sounds in high school EFL education.
Without the aid of ALTs by using the TTS system, high school English teachers can easily
create audio materials to fit their students’ English proficiency.
English speech sounds can be of great help for Japanese EFL learners to study English(Hatori, 1977; Kohno, 1984; Palmer, 1921). However, almost all of the audio language
learning materials used in Japanese high schools are developed by commercial publicationcompanies.
We Japanese-English teachers sometimes feel that such audio materials do not fit ourstudents’ English proficiency. Using TTS will be one way for teachers who want to improveaudio materials for their students during their lessons. We believe that teachers can use TTS
synthesized digital speech sounds so that they can create audio English language learningmaterials suitable for their students, based on their English proficiency level. For teachers tocreate audio English learning materials for high school students, students will need to findHarumi Kataoka, Makiko Ito

52

opportunities to listen to English speech sounds in order to develop their English proficiency.
Their teachers can help develop their students’ English proficiency little by little, by using
TTS speech sounds during their lessons.
We hope that a greater number of English teachers in Japanese high schools use TTS
speech sounds to create audio materials for their lessons and that additional research on
TTS synthetic speech is carried out to further develop high school EFL education.
ACKNOWLEDGEMENTS
The authors gratefully acknowledge the cooperation and support of the high school teachersand students to take time for this research. We would like to express our deep gratitude to
Dr. Shigeru Yamane, Kansai University for his valuable comments on this paper. We also
thank Dr. Eiichi Yamamoto, Professor Taichi Usami, and Professor Takaichi Okuda, Kansai
University for their warm encouragement to our high school English educational studies.
NOTES
1. We received permission through the selling agent of an audio database in this study tocreate TTS CD-ROMs.
2. Mr. Kenji Otsuka has been teaching English in public junior high schools in Hokkaido
since 1986, and he was awarded as a professional English teacher by the Ministry of
Education, Culture, Sports, Science and Technology (MEXT) in 2010.
3. According to Pallant (2007, p. 6, p. 95), Cronbach’s alpha of a scale should be above 0.70.
4. A two-tailed independent t -test: Effect size d = 0.20, small effect size (S); d = 0.50, medium
effect size (M); d = 0.80, large effect size (L).
5. A two-tailed dependent t -test: Effect size r = 0.10, small effect size (S); r = 0.30, medium
effect size (M); r = 0.50, large effect size (L).
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Appendix A. Ten English
Sentences in the Cloze Test

Appendix B. Activity Sheets (1) and (2)