L2 research | phonetics & phonology | SLM | chapters

Flege, J. (1995) The Phonetic Study of Bilingualism. In G. Bloothooft, V. Hazan, D. Huber & J. Llisterri
(Eds) European Studies in Phonetics and Speech Communication. Utrecht: OTS Publications, Pp. 98-103.

Flege, J. (1992) Speech learning in a second language. In C. Ferguson, L. Menn, & C. Stoel-Gammon
(Eds) Phonological Development: Models, Research, and Application. Timonium, MD: York Press, Pp.
Chapter published before 2000.
For later chapter click
Chapters after 2000
Flege, J., Munro, M., & MacKay, I. (1996). Factors affecting the production of word-initial consonants in a
second language. In R. Bayley & D. Preston (Eds) Second Language Acquisition and Linguistic Variation.
Amsterdam: John Benjamins,  Pp. 47-73.
Flege, J. (1995). Second-language Speech Learning: Theory, Findings, and Problems. In W. Strange (Ed)
Speech Perception and Linguistic Experience: Issues in Cross-language research. Timonium, MD: York
Press, Pp. 229-273.
Summary. Many earlier studies led the the creation of the SLM, but this is the first full-blown
presentation of the model. When researchers refer to the model in a single citation, this is often the
chapter that is cited even though the model continued to be elaborated over the following decade. The
stated aim of the SLM is to account for age-related changes in the ability to produce and perceive L2
sounds, that is, position-sensitive vowels and consonants. The model posits that the processes and
mechanisms that permit successful L1 speech acquisition -- including the ability to establish phonetic
categories -- remain intact over the life span. Gone is an earlier distinction between "identical", "similar"
and "new" L2 sounds. Instead, the likelihood of phonetic category formation is hypothesized to
increase as a function of the perceived phonetic dissimilarity of an L2 sound from the closest sound(s)
in the L1 inventory. In the absence of phonetic category formation, the properties of an L2 sound and
a neighboring L1 sound may merge to form a "composite" category. The model posits that the phonic
elements present in the L1 and L2 inventories exist in a common phonological space and may interact
with one another, leading in some cases to a "deflection" of neighboring L1, L2, and L1/L2 categories
to maintain phonetic contrast in the bilingual's dual system.
Flege, J. (1988). Effects of equivalence classification on the production of foreign language speech sounds, In
A. James & B. Leather (Eds) Sound Patterns in Second Language Acquisition. Dordrecht: Foris, Pp. 9-39.
This aim of this 177-page chapter was to "identify and develop theoretical issues of importance with
regard to the production and perception of sounds found in a foreign language." It reviewed nearly all
the literature dealing with L2 speech learning that existed up to 1983. (Publication was, alas, delayed
by five years.) The findings summarized here formed the underpinnings of what later became the
Speech Learning Model
"foreign accent.  Effects of a foreign accent: Accent detection, Diminished acceptability, Diminished
intelligibility, Negative evaluation.
Factors causing accent: Age and amount of L2 experience, L2 input,
Motivation and affective factors, Style and social meaning, individual differences, listener effects.
Phonological and phonetic factors: A two-level model of production, Phonological rules, Phonological
and phonetic features, New vs. similar sounds.
Perceiving L2 speech sounds: Factors affecting
segmental perception, Interlingual identification, Phonological filtering, Reinterpretation,
: Maintenance, Learing, Loss, Phonetic category prototypes  Mechanisms causing accent:
Maintenance, Learning, Loss, Hypercorrection  
Linguistic factors: Orthographic effects, Word familiarity,
Phonetic context, Coarticulation, Basis of articulation  
Phonotactics and syllable structure: English /r/
and /l/, Production by Japanese learners, Production and perception of /r/ and /l/, Word stress  
: Intrinsic timing, Extrinsic timing,  English differential vowel duration, English vowel tensity,
Phonemic length distinctions  
Consonant timing:  Voice onset time, VOT in child speech, The
modification of VOT, VOT in L2 speech acquisition, VOT in L2 perception  
Emerging issues and
:  Phonological translation,  Peripheral sensory feedback, Attention to speech, Strategies
Flege, J. (1991). Perception and production: The relevance of phonetic input to L2 phonological acquisition.
In T. Heubner & C. Ferguson (Eds) Crosscurrents in Second Language Acquisition and Linguistic Theory.
Philadelphia: John Benjamins, Pp. 249-289.

Hammond, R. & Flege, J. (1990). The acquisition of second language phonological systems in a
communicative framework. In B. Lawton & A. Tamburri (Eds) Romance Languages Annual 1989, Volume I.
Purdue: Purdue Research Foundation, Pp. 671-676.

Flege, J. (1988). The production and perception of speech sounds in a foreign languages. In H. Winitz (Ed)
Human Communication and Its Disorders, A Review 1988. Norwood, N.J.: Ablex, Pp. 224-401.
Flege, J. (1992). The intelligibility of English vowls spoken by British and Dutch talkers. In R. Kent
(Ed.)Intelligibility in Speech Disorders: Theory, Measurement, and Management. Amsterdam: John
Benjamins, Pp. 157-232.
The research presented here examined the intelligibility of English vowels spoken by native speakers
of Dutch within the framework of that model. The preliminary version of SLM presented here differs in
important respect from the model formally presented by Flege (1995). Click
here for details.

The L2 production experiment examined six English vowels spoken by eight native speakers of British
English and 50 Dutch adults, all university students aged 20-25 years who had all begun to learn
English in school at the age of 12 years. Subgroups of the Dutch participants (n=16 each) were
established based on overall degree of foreign accent (FA) in the production of English sentences.
The assumption was made that the subgroups differed in experience in English, most for the Mild FA
group and least for the Strong FA group. In support of this assumption, all members of the former
group were majoring in English whereas most members of the latter group were engineering students
who do not seem to have pursued the study of English beyond the formal academic requirements.

L2 vowel production accuracy was assessed by determining the percentage of times the English
vowels were identified as intended by three native speakers of British English, who used keywords to
signal their identifications. One vowel examined, /ɪ/, was as operationally classified as an “identical”
vowel and another vowel, /æ/, was classified as a “new” vowel. The remaining four vowels examined,
/i/, /u/, /˄/ and /ɒ/, the vowel in
hot) were classified as “similar”. The classifications just mentioned
were based on a “phonetic symbol” test (“new” if the L2 vowel is traditionally represented by an IPA
symbol not used for an L1 vowel) and the distances between L1 and L2 vowels seen when visually
inspecting plots of the vowels in an F1-F2 acoustic vowel space.  

The study tested two specific hypotheses regarding the effect L2 experience on L2 vowel production.
First, participants in the three Dutch subgroups would not differ from one another or from the native
English speakers in producing the “identical” L2 vowel because an unmodified use of a Dutch vowel
in English would go undetected by native English speaking listeners. Second, production of the “new”
vowel would improve with experience. Both predictions were confirmed. The Mild FA and Moderate FA
groups were found to produce the new vowel /æ/ more accurately than the Strong FA group did, but
did not differ from native speakers of English.

Somewhat different results were obtained when the vowels were presented for identification to native
speakers of American English were asked to classify the same vowels using keywords. A between
group difference, suggesting an effect of L2 experience on L2 vowel production, was obtained was
obtained for the “new” vowel /æ/. However, an unexpected between group difference was also
obtained for one of the “similar” vowels, /ɒ/. This suggested the importance, in a study that relies of
listener judgments to assess L2 production accuracy, of using listeners who are native speakers of
the variety of the L2 that has been learned.
Summary: This chapter, based on a presentation at Stanford University, further develops ideas later
incorporated into the Speech Learning Model. The aim of the chapter was to provide a "brief overview
of research that has described L2 learners' production and perception of L2 sounds". It starts with the
: This chapter, based on a presentation at Stanford University, further develops ideas later
incorporated into the Speech Learning Model. The aim of the chapter was to provide a "brief overview
of case, L2 production errors may arise from an "inappropriate use of previously acquired [i.e., L1]
research that has described L2 learners' production and perception of L2 sounds". It starts with the
structures", structures", that is, cross-language interference. The author notes the common view that
learners often that is, cross-language interference. The author notes the common view that learners
often attempt to attempt to "decompose" L2 words into sequences of L1 phonemes but stresses that
the simple substitution "decompose" L2 words into sequences of L1 phonemes but stresses that the
simple substitution L1 for L2 "sounds" is merely a starting point for, as demonstrated by evidence
presented in the chapter even most adults who learn an L2 eventually modify previously established
patterns of speech production and perception when attempting to deal with the sound system of an L2.
Thus, the differences one might observe between native and non-native speakers often involve more
than just the maintenance of old articulatory habits (p. 566).
Sections: Production vs. perception, IInterlingual identification, New vs. similar sounds, Equivalence
classification, Defining the "new" vs."similar" distinction, Vowel production, L2 consonant production,
Early versus late learners, Realization rules, Vowel production, Individual differences,  A critical
period?  Changes in speech learning, Linguistic factors,  Summary
A recurrent them of the chapter is that many aspects of L2 production can be understood in terms of
"how L2 sounds are categorized. L2 speech learning is not always just "old wine in new bottles" (p.
566)The author hypothesizes that as L1 categories develop in children, they become ever more
efficient for the production and perception of L1 sounds. He suggests foreign accents are likely to be
evident for individuals who begin learning an L2 after "about the age of five to seven years" because,
as the result of L1 category development, L2 learners become less likely to establish new "phonetic
categories for certain L2 sounds and thus [to produce] them accurately" (p. 597). Although this
hypothesis was incorporated into the first formal presentation of the SLM in 1995 (in W. Strange,
Editor) later research undermined the view that an important shift occurs in the ability to learn L2
speech at about the ages of 5-7 years. Children's L1 phonetic categories continue to develop slowly,
in some cases not reaching adult levels until the age of about 12-14 years. Also, the presence of
foreign accent has been observed in the speech of many children who began learning an L2 before
the age of 5 years, even after years of L2 use.
Flege, J. & Hillenbrand, J. (1987) Limits on Pronunciation Accuracy in Foreign Language Speech Production,
In G. Ioup & S. Weinberger (Eds) Interlanguage Phonology: The Acquisition of a Second Language Sound
System. Rowley, MA: Newbury House, Pp. 176-203.
This chapter examines second language speech acquisiton and work focusing on the remediation of
articulatory errors in monolingual children. The first question was whether "new" L2 sounds -- those
without an obvious equivalent in the L1 -- would be produced more or less accurately than "similar" L2
sounds that differ phonetically from a counterpart in the L1. The second question addressed by this
study was whether accuracy in the production of phonetic segments in an L2 depends on the amount
of attention that can be allocated to the production of speech.

Four groups participated in the three conditions of what was described to the participants as a study of
coherent story including sentences that began with each of the phrases from the original reading task.  

Four groups of young adults participated: (1) monolingual native speakers of English (2) native French
speakers who were residing in Chicago (3) students at Northwestern University who had spent the
previous academic year in Paris (4) native English speakers who taught French at an American
university. The American professors had resided in France somewhat longer than the American
students and, unlike the students, used French on a regular basis with native French-speaking

The English monolinguals produced only English speech materials (Sets 1 and 2) whereas the
remaining three groups produced both English and French materials (Sets 3 and 4) in counterbalanced
order. The dependent variables measured acoustically were VOT (in msec) of word-initial tokens of
French and English /t/ and second formant frequencies (F2) in the production of three vowels. French
/t/ was classified as a similar L2 sound for native speakers of English inasmuch as it is produced with
substantially shorter VOT values than is the /t/ of English. French /u/ was also classified as similar
inasmuch as its production differs, in terms of F2 values, from the /u/ of English. Finally, the front
rounded /y/ of French was classified as "new" because it is labelled using an IPA symbol not employed
in the phonetic description of vowels in English. Moreover, in terms of F2, French /y/ differs far more
from the English /u/ than does the French /u/.
Flege, J. (1999). Age of learning and second language speech. In D. Birdsong (Ed.)
Second Language Acquisition and the Critical Period Hypothesis. Hillsdale, NJ:
Lawrence Erlbaum. Pp. 101-132.

Key words: Speech Learning Model (SLM),confounds, confounded factors, age, age of
L2 learning, AOA, age of arrival, age of first exposure

Flege, J. (1997). English vowel production by Dutch talkers: More evidence for the
"new" vs "similar" distinction". In A. James and J. Leather (Eds) Second-language
speech, Structure and process. Berlin: Mouton de Gruyter, Pp. 11-52. [Studies in
Second Language Acquisition, 13.  ISBN 3-11-014126-4]

Bohn, O.-S. and Flege, J. (1997). Perception and production of a new vowel category
by second-language learners. In A. James & J. Leather (Eds) Second-language
speech: Structure and process. Berlin: Walter de Gruyter, Pp. 53-74. Studies in Second
Language Acquisition, 13.  ISBN 3-11-014126-4]