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研究論文

Examining the Role of Prosody Shadowing in
Sentence Comprehension for Japanese EFL Learners
NAKANISHI, Hiroshi(Seinan Gakuin University)

1. Introduction
The process of comprehending languages involves multiple stages, such as input
perception, lexical, syntactic, semantic, contextual, and pragmatic processing. Notably,syntactic processing, places the greatest cognitive burden on Japanese EFL learners. It
exhausts their finite working memory (WM), which leaves limited resources available
for memory retention or higher-level cognitive functions, such as inference andcontextual processing (Nakanishi & Yokokawa, 2011; Nakanishi et al., 2019).
One reason for the limited automaticity in syntactic processing is that Japanese
EFL learners, unlike native English speakers, cannot immediately use prosodic
information during sentence comprehension (Nakamura et al., 2020). However,prosody provides the syntactic structure of utterances (Frazier et al., 2006), andsentences that offer such prosodic cues (e.g., pausing at the main clause, raising thepitch) are presumed to lighten the cognitive load on syntactic processing (Kadota,
2007; Nakamura, 2012; Yoshikawa, 2006).
English shadowing, a technique that requires learners to repeat the provided
model speech immediately, is expected to help promote automatic syntactic processing.
This assumption is based on two factors. First, frequent exposure to sentences withspecific syntactic patterns improves the processing of sentences with the samestructure, a phenomenon known as syntactic priming (first language: Bock, 1986;
Pickering & Branigan, 1998, second language: Morishita et al., 2010; Sakakibara &Yokokawa, 2015). Speakers tend to unconsciously learn and repeatedly use theimmediately preceding processed sentence when they create a sentence (Kadota, 2015).
Second, shadowing directs learners’ attention mainly to prosody aspect and updates
their speech database, stored in their mental lexicon, not only at the segmental but
also the prosodic level (e.g., pitch range). Some previous studies have reported
improvement in Japanese EFL learners’ prosody through repeated shadowing training(Hori, 2008; Mori, 2011). For example, Hori (2008) revealed that students’ originally
narrow pitch range became wider and closer to the pitch range of native English
speakers through shadowing the same passages 15 times.

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Following these studies, Nakanishi (2023) explored the effects of repeatedshadowing with prosodic structures (e.g., “The farmer that the lady loved % grows acrop in the field. : % indicates a prosodic boundary) . The main finding demonstrated
that repeated shadowing led to improved accuracy, reading time (RT), and solution
time (ST) in the posttest compared to the pretest for all participants. Furthermore, thegroup with higher proficiency outperformed the group with lower proficiency in termsof accuracy and RT for processing object relative clauses. However, regarding ST, thegroup with lower proficiency exhibited longer ST during the pretest, although thisdiscrepancy was not observed in the posttest. Notably, the study had limitations, suchas the absence of a control group (e.g., a listening training group) to isolate the specificeffects of shadowing. Additionally, the participants' proficiency levels were relatively
high, even in the lower proficiency group, with most students classified at CEFR levels
B1 or B2.
2. Purpose of this study
The purpose of this study was to investigate whether repeated shadowing
training aids less proficient learners in processing sentences containing object relative
clauses, which are identified as cognitively demanding sentences (Gibson, 1998;
Grodner & Gibson, 2005; Hashimoto, 2011, 2012; Sakakibara & Yokokawa, 2015;
Yokokawa et al., 2014), as compared to repeated listening training. Furthermore, thestudy was to explore whether shadowing is particularly beneficial for sentences thatcarry cognitive load, such as those containing object relative clauses, by comparing
them with more syntactically simple sentences (simple transitive sentences).
3. Method
3.1 Participants
The study was conducted with 46 Japanese EFL undergraduates, consisting of 21
males and 25 females. Their language proficiency was assessed via the Oxford Online
Placement Test (OOPT), resulting in scores spanning from 11 to 57 (M = 29.09).
According to the Common European Framework of Reference for Languages (CEFR),
the participants comprised of 10 at A1 (Beginners), 29 at A2 (Pre-Intermediate), andseven at B1 (Intermediate). The participants were split into a listening training group
and a shadowing training group. No significant disparity in the average scores
between these two groups was observed ( t (44) = -0.788, ns).
3.2 Procedure
All individuals involved in the study were required to undertake pre/post
evaluations (in other words, pre/post reading aloud tests) as well as either listening orExamining the Role of Prosody Shadowing in
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51

shadowing training tasks. The entire process was carried out in a Computer Assisted
Language Learning (CALL) classroom. For the purpose of assessment, the voices ofparticipants during the pre/posttests and during the listening/shadowing training
were captured on a computer.
3.2.1 Pre/Posttests
Every participant was required to undertake a reading-aloud test both prior toand subsequent to the listening/shadowing training sessions. The tests included 18
total sentences, including 12 of which were target sentences (relative clause) and 6
filler sentences (see Appendix A). All words incorporated in the sentences were selectedfrom the New JACET List of 8,000 Basic Words (Committee of Revising the JACET
Basic Words, 2016). The head nouns in all experimental sentences were animate, citing
Traxler et al. (2002) and Hashimoto (2012), since inanimate head nouns simplify theprocessing of relative clauses, thereby eliminating any influence of animacy on thecomplexity of processing relative clause sentences.
All the target sentences comprising a relative clause consisted of 12 words (e.g.,“The mother that the baby loves washes the dishes in the kitchen."), and filler
sentences containing present perfect progressive with a transitive verb consisted of 10
words (e.g., “The baby has been baking a cake in his room."). Different sentences were
employed for the pretests and the posttests.
The reading-aloud test incorporated semantic judgment tasks, so half thesentences were semantically correct (e.g., " The expert that the students like teach his
subject at the college."). Half were incorrect (e.g, “The climber that the artist wears
drew a picture in the studio."). Participants were presented with a total of 18 sentenceson paper. They were required to read each sentence aloud and declare "Maru (True) " ifthe sentence was semantically valid or “Batsu (False)” if it was not.
3.2.2 Listening/Shadowing Training Sessions
The listening/shadowing sessions consisted of 75 sentences of which 50 weretarget sentences (relative clause) and 25 were fillers (see Appendix B). Every word
used in the sentences was chosen from the New JACET List of 8,000 Basic Words.
Each target sentence consisted of 12 words (e.g., "The swimmer that the climber meetsswims in the sea for the race."), and filler sentence contained 10 words (e.g., “The aunt
has been riding a bicycle in the ocean. ").
For auditory guides, a male native American English speaker’s voice wasrecorded at a rate approximately 188 words per minute (articulation rate). A
0.5-second pause was placed at the appropriate syntactic boundaries (e.g., “Theswimmer that the climber meets % swims in the sea for the race.” : % indicates a

NAKANISHI, Hiroshi

52

prosodic boundary) using Audacity 3.2.1, a freely available sound editing software(Audacity Team, 2021). The waveforms and pitch tracks of the sentences are displayedin Figure 1.
To ensure sentence processing, printed copies of sentences were provided to theparticipants. Both the listening and shadowing groups received audio sentences at
10-second intervals. While the listening group listened to each sentence, theshadowing group shadowed what they heard. Subsequently, participants of bothgroups were asked to determine the semantic validity of the sentence, responding witheither "Maru (True)" or "Batsu (False)". The training session for both groups lasted
approximately 20 minutes.
Figure 1
Example of waveform and pitch contour in target sentence

Figure 2
Example of waveform and pitch contour in filler sentenceExamining the Role of Prosody Shadowing in
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53

4. Results and Discussion
4.1 Results of Pre/Posttest Performances for Target Sentence
Tables 1 and 2 provide the descriptive statistics for accuracy (Score), reading time
(RT: sec.), and solution time (ST: sec.) in the reading-aloud tests for Target Sentence.
Score represents the average number of correct responses in the semantic judgmenttask. Both RT and ST were measured employing via Audacity, with only thosesentences that were accurately answered in the semantic judgment task were includedin the measurement. RT indicates the time from the beginning of the sentence to theend of the sentence, and ST indicates the time from the end of reading to the beginningof answering the semantic judgment task.
To compare the effects of training, we did a two- way ANOVA analysis for training
type and pre/posttest. Regarding score, the two-way ANOVA revealed no significant
main effect in terms of training type (F (l,88) = .230, ns, partial η2 =.003) but showedsignificant main effect in terms of pre/posttest (F (l,88)=4.167, p < .05, partial η2 =.045).
The analysis indicated no significant interaction between the variables of training type
and pre/ posttest at F (l,88) = .407, ns., partial η2 =.005.).
As for RT, the results of the two-way ANOVA revealed no significant main effectfor training type (F (l,88) = .011, ns, partial η2 =.000), whereas the main effect of the
pre/posttest was significant (F(l,88) = 7.062, p < .01, partial η2 =.074). The RT revealed
no significant interaction between training type and pre/posttest (F (l,88) = .184, ns,partial η2 =.002).
Regarding ST, the two-way ANOVA revealed no significant difference for training
type (F (l,88) = 1.315, ns, partial η2 =.015). However, a significant difference exists
between the pretest and posttest (F (l,88) = 17.716, p < .01, partial η2 =.168). The
analysis indicated no significant interaction between the variables of training type andpre/ posttest at F (l,88) = .041, ns., partial η2 =.000).

Table 1
Descriptive statistics of the reading-aloud test data for Listening Training Group
Score

RT

ST

Test

Pre

Post

Pre

Post

Pre

Post

Avg.

6.62

7.14

6.75

6.17

3.37

1.94

S.D.

1.99

2.13

1.05

0.87

1.59

1.04

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Table 2
Descriptive statistics of the reading-aloud test data for Shadowing Training Group
Score

RT

ST

Test

Pre

Post

Pre

Post

Pre

Post

Avg.

6.56

7.56

6.84

6.03

2.93

1.64

S.D.

1.71

1.29

1.76

1.06

2.20

0.98

4.2 Results of Pre/Posttest Performances for Filler Sentence
Tables 3 and 4 provide the descriptive statistics for Score, RT, ST in thereading-aloud tests for Filler Sentence.
To compare the effects of training, we did a two- way ANOVA analysis for training
type and pre/posttest. Regarding score, the two-way ANOVA revealed neither
significant main effect in terms of training type (F (l,88) = .147, ns, partial η2 =.002)
nor pre/posttest (F (l,88) = 2.856, ns, partial η2 =.031). The analysis indicated nosignificant interaction between the variables of training type and pre/posttest at F
(l,88) = .532, ns., partial η2 =.006).
As for RT, the results of the two-way ANOVA revealed neither significant main
effect for training type (F (l,88) = .796, ns, partial η2 =.009) nor pre/posttest (F (l,88) =3.016, ns, partial η2 =.033). The RT revealed no significant interaction between
training type and pre/posttest (F (l,88) = .031, ns, partial η2 =.000).
Regarding ST, the two-way ANOVA revealed no significant difference for training
type (F (l,88) = .037, ns, partial η2 =.003). However, a significant difference exists
between the pretest and posttest (F (l,88) = 7.627, p < .01, partial η2 =.080). The
analysis indicated no significant interaction between the variables of training type andpre/ posttest at F (l,88) = .176, ns., partial η2 =.002.).

Table 3
Descriptive statistics of the reading-aloud test data for Listening Training Group
Score

RT

ST

Test

Pre

Post

Pre

Post

Pre

Post

Avg.

4.29

4.52

4.49

4.18

2.33

1.47

S.D.

1.19

1.33

0.82

0.64

1.19

0.89

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55

Table 4
Descriptive statistics of the reading-aloud test data for Shadowing Training Group
Score

RT

ST

Test

Pre

Post

Pre

Post

Pre

Post

Avg.

4.20

4.80

4.31

4.06

2.07

1.43

S.D.

1.04

1.19

0.83

0.76

1.88

0.87

5. Discussion
The first goal of the present study was to explore whether the repeatedshadowing training can benefit lower-proficiency learners in comprehending object
relative clauses, which are known to be cognitively strenuous for Japanese English
learners, relative to repetitive listening training.
Tables 1 and 2 show that both the shadowing and listening groups experienced
improvements in processing object relative clauses. Notably, not only did theprocessing accuracy of these clauses increase, but the reading and comprehension
times for them also sped up.
There are two main reasons for the observation of this training effect in thelistening group. One is that repeated encounters with the target sentence resulted insyntactic priming, facilitating the processing of that specific sentence structure. The
occurrence of syntactic priming is reported to be apparent not only in language
production but also in language comprehension. According to findings by Noppeney
and Price (2004), a succession of sentences bearing similar syntactic structures leads toa reduction in the time required to process subsequent sentences. The other reason isthat the speech involving object relative clauses used in both listening and shadowing
group provided sufficient prosodic cues (including pauses and pitch rises at syntactic
boundaries), which served to promote comprehension in both the shadowing andlistening groups. As Nakamura et al. (2015) noted, in contrast to English native
speakers, Japanese EFL learners often struggle to utilize prosodic cues effectively insyntactic construction. This problem is particularly noticeable among less proficientlearners (Nakanishi, 2021a). However, through repeated exposure to sentences inwhich prosodic and syntactic information coincide, they may gradually acquire theability to utilize prosodic cues in the construction of sentences.
The second purpose of this study was to examine whether shadowing proves to be
especially valuable when processing sentences carrying significant cognitive load, suchas containing object relative clauses, by comparing them to sentences with simpler
syntactic structures (i.e., simple transitive sentences).

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As Tables 3 and 4 show, the training effect was not as apparent in sentences withlow cognitive load as in sentences with high cognitive load. Specifically, whencomparing pre- and post-training, only ST was significantly faster, but no significant
differences were found in score and RT. In previous investigations into prosody andsyntactic processing in first languages, syntactically ambiguous sentences (e.g.,"Whenever the guard checks the door % it's locked") are frequently employed as
experimental sentences (Speer et al., 1996; Snedeker & Trueswell, 2003). Extending
this line of research to second language learners, Nakanishi (2021b) revealed that
more proficient learners were less reliant on prosodic cues in comprehending
syntactically simple sentences as compared to their usage in understanding
syntactically complex sentences. Therefore, it is suggested that prosodic cues can be
more effectively utilized in the interpretation of syntactically complex sentences.
5. Conclusion and Further study
The findings from this study suggest that learner's syntactic processing can beenhanced through repetitive processing of sentences where prosodic and syntactic
boundaries align, regardless of whether the approach is shadowing or listening. It also
appears that this training method may be more successful when dealing withsentences of a higher syntactic complexity.
Subsequent exploration will involve comparing prosodic attributes of learners'
speech during the pre- and post-training assessments across both shadowing andlistening approaches. One of the observed benefits of shadowing is the enhancement ofprosodic features like pitch in learners’ English expressions (Mori, 2011). Acoustic
analysis will be used to determine whether shadowing enables learners to assign
prosodic information that clarifies syntactic boundaries when they speak syntacticallycomplex sentences.
Acknowledgment
This study was partially supported by JSPS Grant-in-Aid for Scientific Research(C), (PI: Hiroshi Nakanishi, No. 23K00786).
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Examining the Role of Prosody Shadowing in
Sentence Comprehension for Japanese EFL Learners

Appendix A
Sample Target Sentences for Pre/Post-Reading-Aloud Test
Target Sentences
The fighter that the lady loves won the matches in the ring.
The owner that the drivers drank checked the cars on the street.
Filler Sentences
The leader has been eating the team in the park.
The driver has been driving his car on the road.
Appendix B
Sample Target Sentences for Listening/ Shadowing Training
Target Sentences
The swimmer that the singer ate sings a song on the spot.
The author that the readers loved writes a book in his style.
Filler Sentences
The writer has been writing the play for the actors.
The mother has been cooking her children for a meal.

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