CFL learners’ perception of temporally modified speech

Jun Da ( 笪骏 )Middle Tennessee State University

Jun.Da@mtsu.eduDenver, 11/19/2011

1. Speech rates in CFL learning and instruction

• Speech rate has been one of the many factors that are often controlled by native speakers and instructors to assist learners’ listening comprehension. – In the real world

• Average normal speech rate for Chinese native speakers– Meng (2005): 244.45 characters/min

• Foreigner talk/teacher talk

– In CFL instruction• Speech rates of selected CFL textbooks (Da 2009)

– Chinese Link (1st edition)– Integrated Chinese (2nd edition)

• Prescribed speech rates for CFL learners: HSK– Basic level: 120-170 characters/min– Elementary-intermediate: 170-220 c/m for

– Observation• There are disparities between normal speech rates and those used in CFL

learning and instruction.

Normal speech rates (Meng 2005)

Speech rates of Chinese Link and Integrated Chinese

Slow Normal Fast

Integrated Chinese

65 111 176

Chinese Link 81 115

2. Learner needs and solutions (I)

• Pedagogy– Authentic materials are preferred for communicative

language learning and instruction.• Learner needs– Many beginning and (sometimes) even intermediate level

learners (intuitively) feel that slow speech rate would help their listening comprehension.

• A practical problem– While multimedia authentic materials are readily available,

it is often impossible to find materials that are slow enough for those needy CFL learners.

2. Learner needs and solutions (II)

• Possible solutions: – Instructors/native speakers produce slow rate audio materials for CFL

learners.• Examples: CFL textbooks such as Integrated Chinese (Yao, et al 2005), and

Chinese Link (Wu, et al 2006), etc.;• Problem: It takes time, effort and experience to produce slow rate audio

learning materials.

– Instructors and CFL learners can use software to vary the playback rate of audio recordings (Da 2011).• Benefits: Everybody can do it; saves instructor’s time;• Software applications:

– Windows Media Player: Available on PC– QuickTime player: Available on Mac and PC– VLC Player: Cross platform (http://www.videolan.org/vlc/)– Audacity: Cross platform (http://audacity.sourceforge.net/)

3. Research questions (I)

• Previous research findings about the effects of varying speech rate on listening comprehension– Empirical research has produced mixed results (Rost 2005, Zhao

1997): • Griffiths (1990): Slower speech rate will improve ESL (English as a Second

Language) learners’ listening comprehension when aided with other simplifications in syntax and rhetorical structure.

• Blau (1990): Simply reducing speech rate from faster to slower did not improve the listening comprehension of intermediate and advanced level EFL learners.

• Zhao’s (1997) with ESL learners: “(a) when given control, students’ listening comprehension improved, and (b) improved comprehension control was achieved by slowing down the speech rate.”

– Research on CFL learners: Not available

3. Research questions (II)

• Questions for this research– Do software modified audio recordings sound

unnatural?• Yes and no, depending on the rate change.

– How do CFL learners perceive software modified audio recordings?• Can CFL learners detect any speech rate change, e.g.,

do the modified materials sound slow to them?• Does speech rate change help improving CFL learners’

listening comprehension?

1. Objectives and research design2. Data collection3. Results4. Discussions

4. This experiment

4.1 Objectives and research design

• Objectives– To find out and compare CFL learners’ perception of the

speech rates of both unmodified and software modified audio recordings;

– To determine if there is any improved listening comprehension when the same audio clip is slowed down by software.

• Research design– CFL learners listen to 7 unmodified and modified audio

recordings of various speech rates and report their judgment of speech rates and comprehension.

4.2 Data collection (I)

• Subjects– 28 students at Middle Tennessee State University

• 26 true beginners with 2 months of Chinese learning, 3 classroom hours per week;

• 2 native/heritage speakers (excluded in statistical analysis)

– 20 students at Beijing Normal University• Proficiency

– Advanced level (Self reported): 14– Intermediate level (Self reported): 6

• Native languages– Korean, Vietnamese, Indonesian, Portuguese, Thai, English.

4.2 Data collection (II)

• Stimuli: – Seven audio clips

• Chinese Link: – Unmodified CL Normal: cln.mp3– Unmodified CL Slow: cls.mp3 – Modified CL Normal (-25%): cln25.mp3– Modified CL Normal (-40%): cln40.mp3

• 中央人民广播电台《新闻和报纸摘要》 (http://aod.cnr.cn)– Unmodified normal speed: xy1.mp3 – Modified normal (-25%): xy25.mp3– Modified normal (-40%): xy40.mp3

– Average speech rates– Acoustic differences

Average speech rates of the 7 audio clips

Sound file Syllables Duration (seconds) Syllables/Min

CL Normal: cln.mp3 20 9 133CL Slow: cls.mp3 20 17.5 69News Normal: xy1.mp3 35 8.5 247

CL Normal at -25%: cln25.mp3 20 12 100

CL Normal at -40%: cln40.mp3 20 15 80News at -25%: xy25.mp3 35 11.2 188News at -40% xy40.mp3 35 14 150

CL Normal: cln.mp3

CL Slow: cls.mp3 News Normal: xy1.mp3

CL Normal at -25%: cln25.mp3

CL Normal at -40%: cln40.mp3

News at -25%: xy25.mp3

News at -40% xy40.mp3

0

50

100

150

200

250

Syllables/min

Syllables/Min

Average speech rates of the 7 audio clips

Contrast between human produced speech and software modified speech• Modified: Only tempo• Naturally slow: Tempo, pitch and intensity (volume)

Acoustic differences between natural and software modified audio clips

4.2 Data collection (III)

• The Questionnaire– CFL learners’ perception of the speech rate of

those seven clips;– CFL learners’ self-reported comprehension of 3

sample clips• CL normal speed• News report at normal speed• News report at -40% speed

• Sample question

1. Click on the speaker icon below to listen to Audio Clip 1. Then decide if the clip sounds fast, slow or just about right to you. 点击左边的喇叭听录音 1 。然后决定该录音对你来说是快、慢还是不快不满。

Clip 1 Very slow Slow Neither slow nor fast Fast Very fast

很慢 慢 不快不慢 快 很快

To what extend do you understand this clip (您听懂这段录音的程度 )?

Not at all Just a little Somewhat Most part Completely

完全听不懂

听懂一点点 听懂一些

大部分能听懂

完全能听懂

Sample question

4.3 Results (I)

• CFL learners’ perceived speech rates of the 7 audio clips– All subjects– By groups: Novice vs. Intermediate and Advanced

• CFL learners’ self reported comprehension of 3 audio clips– CL normal, News normal and News at -40%– Analysis:

• All subjects• By groups: Novice vs. Intermediate and Advanced

4.3 Results (II)

Qs Sound file SubjectsAverage

speed s.d. Max Min

RangeQ1 CL Normal: cln.mp3 46 2.7 0.8 5 1 4Q2 CL Slow: cls.mp3 46 1.4 0.8 5 1 4Q3 News Normal: xy1.mp3 46 4 0.8 5 1 4

Q4CL Normal at -25%: cln25.mp3 46 2 0.7 3 1 2

Q5CL Normal at -40%: cln40.mp3 46 1.4 0.6 4 1 3

Q6 News at -25%: xy25.mp3 45 3.1 0.9 5 1 4Q7 News at -40% xy40.mp3 46 2.2 1 4 1 3

All subjects: CFL learners’ perceived speech rates

1 2 3 4 5

Very slow Slow Neither slow nor fast Fast Very fast

CL Normal: cln.mp3

CL Slow: cls.mp3 News Normal: xy1.mp3

CL Normal at -25%: cln25.mp3

CL Normal at -40%: cln40.mp3

News at -25%: xy25.mp3

News at -40% xy40.mp3

1

1.5

2

2.5

3

3.5

4

4.5

5

All subjects: CFL learners’ perceived average speed

Average speed

1 2 3 4 5

Very slow Slow Neither slow nor fast Fast Very fast

• A one-way ANOVA was used to test for perceived rate differences among three audio clips of the news clip: Normal, Normal at -25% and Normal at -40%. Perceived speech rates of the three audio clips differed significantly across the three rates, F (2, 134) = 51.7, p < .001.

All subjects: CFL learners’ perceived speech rates

By groups: CFL learners’ perceived speech rates

Qs Sound file All Novice learnersAdvanced leaners

Q1 CL Normal: cln.mp3 2.7 3.1 2.2

Q2 CL Slow: cls.mp3 1.4 1.6 1.1

Q3 News Normal: xy1.mp3 4 4.5 3.5

Q4CL Normal at -25%: cln25.mp3 2 2.3 1.6

Q5CL Normal at -40%: cln40.mp3 1.4 1.5 1.1

Q6 News at -25%: xy25.mp3 3.1 3.6 2.3

Q7 News at -40% xy40.mp3 2.2 2.8 1.3

1 2 3 4 5

Very slow Slow Neither slow nor fast Fast Very fast

4.3 Results (III)

CL Normal: cln.mp3

CL Slow: cls.mp3 News Normal: xy1.mp3

CL Normal at -25%: cln25.mp3

CL Normal at -40%: cln40.mp3

News at -25%: xy25.mp3

News at -40% xy40.mp3

1

1.5

2

2.5

3

3.5

4

4.5

5

Novice learnersAdvanced leaners

By groups: CFL learners’ perceived speech rates

1 2 3 4 5

Very slow Slow Neither slow nor fast Fast Very fast

4.3 Results (III)

All subjects: CFL learners’ self reported comprehension of 3 audio clips

Sound file Subjects Comprehension s.d. Max Min Range

CL Normal: cln.mp3 45 4.5 0.9 5 1 4News Normal: xy1.mp3 45 2.5 1.5 5 1 4News at -40%: xy40.mp3 41 2.6 1.6 5 1 4

1 2 3 4 5 Not at all Just a little Somewhat Most part Completely

完全听不懂 听懂一点点 听懂一些 大部分能听懂 完全能听懂

t-test for News Normal vs. Modified News Normal at -40% : p<0.01

CL Normal: cln.mp3 News Normal: xy1.mp3 News at -40%: xy40.mp31

1.5

2

2.5

3

3.5

4

4.5

5

All subjects: CFL learner’s self reported comprehension of 3 audio clips

Comprehension

4.3 Results (III)

4.3 Results (IV)

Sound fileNovice

learners Advanced learners All learners

CL Normal: cln.mp3 4.2 5 4.5News Normal: xy1.mp3 1.3 4.1 2.5News at -40%: xy40.mp3 1.5 4.4 2.6

By groups: CFL learners’ self reported comprehension of 3 audio clips

1 2 3 4 5 Not at all Just a little Somewhat Most part Completely

完全听不懂 听懂一点点 听懂一些 大部分能听懂 完全能听懂

Novice group: t-test for News at normal vs. News at -40%: not significantAdvanced group: t-test for News at normal vs. News at -40%: p<0.004

CL Normal: cln.mp3 News Normal: xy1.mp3 News at -40%: xy40.mp31

1.5

2

2.5

3

3.5

4

4.5

5

Novice leanersAdvanced learners

By groups: CFL learners’ self reported comprehension of 3 audio clips

4.4 Discussions

• CFL learners, both beginning and advanced level learners do detect speech rate change. Such detection of different speech rates is statistically significant when normal speech rate is reduced by 25% or 40%;

• When normal speech rate is reduced by 40%, significantly improved comprehension is self reported by learners at the intermediate to advanced level by not the novice group. This matches with Zhao’s (1997) findings with intermediate and advanced level ESL learners.

• Findings from this experiment suggest that we can confidently make use of software applications to provide students with learning materials at various speed rates, and thus enabling them to engage in more learning practices.

5. Concluding remarks

• Some issues with current research project– Research design: More stimulus clips– Setting: Homogeneous experiment environment– Questions: Need to ask questions on the

naturalness of software modified speeches

References

• Blau, Eileen, 1990. “The effect of syntax, speed and pauses on listening comprehension.” TESOL Quarterly, 24, 4,746-752.

• Da, Jun. 2009. Speech rate and CFL instructional audio materials preparation. Paper presented at the 7th International Conference on Chinese Language Pedagogy. Guilin, China.

• Da, Jun. 2011. How to adjust the playback speed of audio and video learning materials. Journal of Chinese Language Teaching and Research in the U.S., 2011,93-97.

• Griffiths, Roger, 1990. “Speech Rate and NNS Comprehension: A Preliminary Study in Time-Benefit Analysis.” Language Learning. 40,3,311-336.

• Rost, M., 2005. “L2 listening.” In Handbook of Research in Second Language Teaching and Learning, edited by HinkKel, E., 503-527. Mahwah, NJ: Erlbaum.

• Wu, Sue-mei Wu, Yueming Yu, Yanhui Zhang, and Weizhong Tian, 2006. Chinese Link ( 《中文天地》 ). New Jersey: Prentice Hall.

• Yao, Tao-chung, Yuehua Liu, Liangyan Ge, Yea-fen Chen, Nyan-Ping Bi, Xiaojun Wang, and Yaohua Shi. 2005. Integrated Chinese (2nd Ed.) ( 《中文听说读写》 ). Boston: Cheng & Tsui Company.

• Zhao, Yong, 1997. “The effects of listeners’ control of speech rate on second language comprehension.” Applied Linguistics, 18,1,49-68.

• 孟国 . 2005. 对外汉语听力教学中语速问题的调查和思考 . 《第八届国际汉语教学讨论会论文选》 . 北京