Speech Perception by Non-Native Speakers Declines Drastically in Noisy Conditions

Catherine Caldwell-Harris Boston University

1

Speech Perception by Non-Native Speakers Declines Drastically in

Noisy Conditions

Catherine Caldwell-Harris,Inna Ryvkin, Andrei Anghelescu,

Loraine K. Obler

Catherine Caldwell-Harris Boston University 2 of 23

Expert language processing system

cleans up noisy input -- Wow!

Highly fluent speakers• Fill in from meaning• Are more sensitive to auditory cues

(Barbara Shinn-Cunninghams’ talk)


We already know a lot about factors influencing non-native speech

perception

‘Fluency/ability’ matters; and these factors influence fluency (in order of strength):

• Proficiency• Number of years of language use • Amount and type of current use• Age of acquisition (often determines above factors)

Task and input factors• Noise / environment• Sentence context (predictability of words)


But much less is known about:

How factors that influence skill level interact

• Is early acquisition important even controlling for proficiency and current use?

Does word frequency matter? How do input factors interact?

• Examine word freq in high/low predictable context

Similarity between first and second language

• Those great Dutch learners of English!


Speech Perception In Noise Test (Bilger, 1984)

Participants were instructed to repeat the last word of each sentence.

80 items selected from the original SPIN sentences.Three variables, fully crossed: predictability of target (Predictable/Unpredictable) lexical frequency of target (High/Low) noise (Noise/Clear).

The noise consisted of multi-speaker babble. Signal-to-noise ratio was -2dB for sentence-plus-noise items. Each item is a sentence that was prerecorded by an adult male and

presented in stereo through headphones.

Clear, predictable Noise, predictable Clear, unpredictableNoise unpredictable


Examples of conditions

Predictable Context Target

His plan meant taking a big risk. Hi FreqTom fell down and got a bad bruise. Lo Freq

Unpredictable ContextBill might discuss the foam. Hi Freq I was considering the crook. Lo Freq


Questions in Current Study


• With L1 Spanish, Russian, Mandarin When identifying targets in spoken English

• Predict: Spanish > Russian > MandarinHigh/low frequency of target words• Predict: frequency effects will depend on

proficiencyAge of acquisition• Predict: Doesn’t matter, after controlling for

proficiency?


Procedure

Questionnaire Language History Self-rating of proficiency in L1 and English Adult English Language Use Scale (AELU)

Hearing Threshold determination SPIN meant to be administered 50dB above

hearing threshold. Threshold tested via a Behringer UB502

Eurorack 5 Input Mixer

ENGLISH MANDARIN RUSSIAN SPANISH StatisticalDifferences

Total 25 20 20 20Age 21 21 20 23 n.s.

Verbal SAT 677 570 657 559 (Eng=Rus) >(Mand=Span)

Age ofArrival

14.7 8.3 11.1 Mandarinlatest

Years in US 5.8 11.3 9.8 Mandainfewest

Age ofLearningOnset


AdultEnglish UseScale

20.7(21 totalpossible)

12.3 14.3 13.10 Mandarinleast

Learning History Variables

0

10

20

30

40

50

60

70

80

90

100

Clear Noise Clear Noise

English Mandarin

Predictable, HighFreqPredictable, LowFreqUnpredictable, High FreqUnpredictable, Low Freq

0

10

20

30

40

50

60

70

80

90

100

Clear Noise Clear Noise

Russian Spanish

Predictable HighPredictable LowUnpredictable HighUnpredictable Low


Overview of Results

Native English-speakers performed nearly at ceiling, Mandarin speakers performed most poorly, and Spanish- and Russian-speakers show in intermediate results.

Noise, predictability, frequency matter for all speakers

BUT: Lexical frequency of target is a small effect of native English speakers


Effect sizes for main effects and interactions

Clear Condition

-5

10

25

40

55

70

85

100

-5 5 15 25 35

Age of Arrival in the U.S.

Percentage of Targets Correct

Predictable - High Freq

Predictable - Low Freq

Unpredictable - High Freq

Unpredictable - Low Freq

Poly. (Predictable - HighFreq)

Poly. (Predictable - LowFreq)

Poly. (Unpredictable - HighFreq)Poly. (Unpredictable - LowFreq)

(Native Eng)

Noise Condition

-5

10

25

40

55

70

85

100

-5 5 15 25 35



(Native Eng)

Predictable Hi Freq

Predictable Lo Freq

Unpredictable Hi Freq

Unpredictable Lo Freq

Noise Condition

-5

10

25

40

55

70

85

100

0 5 10 15 20 25 30 35







Linear (Predictable - HighFreq)Linear (Predictable - LowFreq)Linear (Unpredictable - HighFreq)Linear (Unpredictable - LowFreq)

Spanish L1

Russian L1

Noise Condition

-5

10

25

40

55

70

85

100

-5 0 5 10 15 20








(Native Eng)

Mandarin L1Noise Condition

-5

10

25

40

55

70

85

100

0 5 10 15 20 25 30 35









Need more participants to determine cline of Spanish >

Russian > Mandarin

Statistically, group differences greatly diminished when ages-of-arrival are taken into account.

Age-of-arrival effects very strong. Why?Age-of-arrival may organize immigrants’ language

learning environment (Caldwell-Harris et al, under review). Still,plots for language groups show steeper slope

for decline in target word detection with age-of-arrival for Mandarin speakers.

But Mandarin group had on average later age-of-arrival.

ENGLISH MANDARIN RUSSIAN SPANISH StatisticalDifferences

Total 25 20 20 20Age 21 21 20 23 n.s.

Verbal SAT 677 570 657 559 (Eng=Rus) >(Mand=Span)

Age ofArrival


Years in US 5.8 11.3 9.8 Mandainfewest

Age ofLearningOnset


AdultEnglish UseScale

20.7(21 totalpossible)

12.3 14.3 13.10 Mandarinleast

Learning History Variables


Answers in Current Study


• Comparing L1 Spanish, Russian, Mandarin• Confirmed: Spanish > Russian > Mandarin• But: age-of-arrival confoundHigh/low frequency of target words• Confirmed: frequency effects depend on

proficiency• Implies ‘subject/experienced’ proficiency is what

matters for processing. For high proficiency speakers, need very low freq words? Is log transform sufficient?


Second language learning ideal for neural net modeling

Use modeling to clarify proposals about main effects and interactions of:

• The role of frequency (why frequency effects disappear for high proficiency learners)

• Predictability -- test hypotheses about when lower proficiency learners can use context to make predictions

• Vary L1-L2 similarity in simulations• Vary “age of exposure” and intensity of

language contact

Speech Perception by Non-Native Speakers Declines Drastically in Noisy Conditions

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