L2 research | phonetics & phonology | SLM | chapters

Flege, J. and MacKay, I (2011). What accounts for “age” effects on overall degree of foreign accent? In M.
Wrembel, M. Kul and Dziubalska-Kołaczyk, K. (Eds)
Achievements and perspectives in the acquisition of
second language speech: New Sounds 2010
, Vol. 2, Bern, Switzerland: Peter Lang, Pp. 65-82.
Chapters that appeared in 2000 or later.
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Earlier chapters                    
Piske, T., Flege, J., MacKay, I., and Meador, D. (2011). Investigating native and non-native vowels
produced in conversational speech. In M. Wrembel, M. Kul and Dziubalska-Kołaczyk, K. (Eds)
and perspectives in the acquisition of second language speech: New Sounds 2010, Vol. 2,
Switzerland: Peter Lang,  Pp. 195-205.
Mora, J., Keidel, J. and Flege, J. (2011). Why are the Catalan contrasts between /e/-/eh/ and /o/-/oh/ so
difficult for even early Spanish-Catalan bilinguals to perceive? In M. Wrembel, M. Kul and Dziubalska-
Kołaczyk, K. (Eds)
Achievements and perspectives in the acquisition of second language speech: New
Sounds 2010, Vol. 2,
Bern, Switzerland: Peter Lang,  Pp. 183-193.
Mora, J.C., Keidel, J.L. & Flege, J.E. (2015) Effects of Spanish use on the production of
Catalan vowels by early Spanish-Catalan bilinguals. In J. Romero & M. Riero (Eds.)
Phonetics-Phonology Interface, Representations and methodologies
. Amsterdam: John
Summary. Two studies by Mora et al. (here 2015, below, 2011) examined the production and perception
of Catalan vowels by individuals who had learned both Spanish and Catalan by school age. Previous
research focusing on immigrants who learned an L2 after arriving in a predominantly L2-speaking
environment have shown that some early learners continue to pronounce the L2 with a foreign accent and
may produce certain L2 vowels inaccurately. Flege & MacKay (2004) focused on the perception of English
vowels by early Italian-English bilinguals who had lived in Canada for decades. These authors noted
inaccuracy in the perception of L2 (English) vowels by early learners who continued to use the L1 (Italian)
frequently but not by those who used the L1 infrequently.  

But what about individuals who use both the L1
and the L2 frequently in a city like  Barcelona, where
bilingualism is the norm? Sebastan-Gallès & Soto-Faraco (1999, p. 120) observed errors in vowel
perception by early learners in Barcelona, which the authors interpreted as possible evidence for a "lack
of plasticity".  Further, the authors suggested that the malleability of the speech perception system may be
limited "severely" by school age because exposure to the L1 exerts a "very strong constraint" on the
"organization and acquisition of phonemic categories". Pallier et al. (1997, p. B14) concluded that even
early and frequent exposure to an L2 might be insufficient to permit the learning of "two new phonetic
categories which overlap" a single L1 category. Bosch et al. (2000, pp. 215-216) inferred that early
learners continued to represent Catalan vowels as "foreign"  speech sounds for which "stable
representations in long-term memory" were not established.

The results obtained by Mora et al. (2011, 2015), on the other hand, do not support the view that severe
limits exist on the ability of early learners to produce and perceive vowel distinctions found in one of their
two languages, but not the other. The research by Mora et al. confirmed the existence of differences in
accuracy among bilinguals, but showed that the variation is largely determined by patterns of language
Flege, J. (2008). Give input a chance!  In T. Piske and Young-Scholten, M. (Eds) Input Matters in SLA.  
Bristol: Multilingual Matters, Pp. 175-190.
Key words: input, LOR, length of residence, AOA, age of arrival, age, age-related, individual
differences, longitudinal study, long-term memory representation, early learners, late learners, foreign
accent, sound system, amount of input, quality of input, Polish, Chinese, language  use estimates,
percentage L1 use, principle components analysis, language background questionnaire, perceived
foreign accent, pronunciation, immigrants, language dominance, neurological development, phonetic
category, native-speaker input, foreign-accented input, L1 proficiency, confounds, confounds,
self-report, Experience Sampling Method
Summary. This chapter considers the role of input by re-examining data obtained in studies
examining degree of foreign accent (FA) in English sentences spoken by Italian and Korean
immigrants (n = 240 per group). A variable often used to index amount of L2 input, LOR (length of
residence), accounted for little variance in FA. The participants' AOA (age of arrival in the host
country) accounted for far more variance, probably because AOA is a macro-variable that is broadly
related to both the quantity and quality of L2 input (i.e., how much input came from compatriots who
spoke English with a foreign accent). The importance of input has been underestimated in L2
research because of the difficulty inherent in actually measuring input rather than obtaining estimates
via language background questionnaires. The best way to advance the field is to make use of the
Experience Sampling Method (ESM) via dedicated applications on participants' smart phones. The
ESM/EMA approach is based on the principle that participants can respond far more accurately to
simple questions about the here-and-now (e.g., What language are you now using? What is the L1 of
the people you are talking to?) than to broader questions such as  "What percentage of the time do
you use English?" Aggregating responses to simple questions asked many times will likely yield more
accurate assessments of percent L2 use, and provide a way to determine what percentage of L2 input
is foreign-accented.
Flege, J. (2007). Language contact in bilingualism: Phonetic system interactions. In J. Cole and Hualde, J.
(Eds.), Laboratory Phonology 9. Berlin: Mouton de Gruyter, Pp. 353-380.
Summary. This is the last comprehensive exposition of the Speech Learning Model (SLM), a model
which attempts to account for L2 speech learning. The fundamental tenets of the SLM are that (a)
the processes and mechanisms used in successful L1 learning, including the ability to create new
long-term memory representations called phonetic categories, remain intact across the life span, and
(b) the phonetic information needed to distinguish the sounds of an L2 from one another, and from
previously established L1 sounds, remains accessible. The chapter devotes considerable time to
elucuding what happens when new phonetic categories are established, and when they are not
established for L2 sounds that differ auditorily from the closest L1 sound.
Key words: Speech Learning Model (SLM), early vs. late learners, production vs. perception,
plasticity, neural maturation, critical period, L2 input, ultimate attainment, Chinese, Korean, LOR,
immigrants, confounds with age, confounded factors, bilinguals, constraints, mutual influence,
L2-on-L1 effect, language dominance, phonetic interaction, perceptually assimilate, equivalence
classification, phonetic category formation, phonetic category assimilation, phonetic category
Key words: conversational speech, fluent early bilinguals, early vs. late bilinguals, vowel production
accuracy, native Italian, auditory evaluation, spelling pronunciation, L2 vowel production
Summary. to appear.
Key words: second language, L2, individual differences, age effects, age-related effects, age of L2
learning, ultimate L2 proficiency, L2 input, amount of L2 input, quality of L2 input, early learners,
late learners, AOA, age of arrival, LOR, length of residence, immersion, immigrants, neural
maturation, language background questionnaire, plasticity, critical period, foreign accent, perceived
foreign accent, VOT, native Italian, Korean, frequency of L1 use, social networks, immigrants,
delayed repetition, maturational constraint,  phonological acquisition, grammaticality judgment test,
confounds, subgroup matching procedure, cognitive development, phonetic category development,
cross-language phonetic differences, SLM, Speech Learning Model, perceived phonetic
dissimilarity, input, motivation, L1 proficiency, macro variable, frequency of L2 use, phonological
short-term memory
Summary. To appear.
Key words: vowel perception, Catalan, Spanish, early learners,  bilinguals, bilingualism, bilingual
vowel perception, frequency, frequency of L2 use,  categorical,  L2 performance, AOA, age of
learning, late learners, maturation, categories, new categories, single-category assimilation,
robust contrasts, dialect variation, neutralize, functional load, foreign-accented input, phonological
variation, degree of robustness, experience, AXB, production, read-aloud task, percent L2 use,
identification, discrimination, category boundary
Summary. See above.
McAllister, R., Flege, J. and Piske, T. (2003). Second language comprehension: A discussion of some
influencing factors. In L. Costamagna and S. Giannini (Eds) La Fonologia dell’Interlingua. Milan:
Fancoangeli, Pp. 57-70.
Key words: second language phonology, contrastive, phonetic realization, perceptual foreign
accent, L1 use, L2 vowel perception, native Italian, new phonetic categories, AOA, native Italian,
discrimination scores, phonetic perception, SLM, word final consonants, unaspirated, functionally
equivalent, interference, frequency of L2 use, feature hypothesis, phonetic category formation,
Swedish, vowel quantity, contrastive use, spectral vs. temporal cues, English, Estonian, Spanish,
phonological length distinction, feature prominence, individual differences, age of arrival, word
familiarity,  L2 use
Summary. to appear.
Flege, J. (2003). Assessing constraints on second-language segmental production and perception. In A.
Meyer and N. Schiller (Eds) Phonetics and Phonology in Language Comprehension and Production,
Differences and  Similarities. Berlin: Mouton de Gruyter. Pp. 319-355.  
Key words: Speech Learning Model (SLM), age, age of learning, L2, second language, age of L2
learning, input, use, L2 use, amount of L2 use
Summary. to appear.
Trofimovich, P., Baker, W., Flege, J., and Mack, M. (2003). Second language sound learning in children
and adults: Learning sounds, words of both? In Proceedings of the Boston University Conference on
Language Development 27. Sommerville: Cascadilla Press. pp. 775-786.
Key words: second-language, production, adults, children, vowel production, English, Korean,
perceived cross-language similarity, perceived dissimilarity, equivalence classification, phonetic
realization, phonetic context, word frequency, word familiarity, lexical factors, segmental factors,
picture-naming task, years of English education, SLM,
Summary. to appear.
Flege, J. (2003). Methods for assessing the perception of vowels in a second language. In E. Fava & A.
Mioni (Eds) Issues in Clinical Linguistics. Padova: UniPress, Pp. 19-44.
Key words: second language, segmental perception, vowel perception, identification, discrimination,
AXB, ABX, triadic, guessing, AX, same-different, accuracy, relation between prodution and perception,
Korean, Japanese, Czech, Hungarian, Arabic, Portuguese, German, Dutch, individual differences,
memory, categorial, categorial discrimination, Perceptual Assimilation Model, Speech Learning Model,
A', A-prime
Summary: This chapter summarizes some of the many techniques that have been used to examine
the perception of L2 vowels and consonants. It is crucial to understand if L2 learners can identify L2
sounds like native speakers. However, doing so is difficult.  Major problem with identification
experiments is how to provide Ss with labels they can readily understand and use. Another is that ID
results are subject to range and frequency effects.  This is why most research has focused on the
discrimination of the contrasts that exist between pairs of distinct L2 sounds. In discrimination
paradigms a key objective is find techiques that are bias free (characteristics of the AXB but not ABX
paradigm) and to be clear about the level of processing at which stimuli are processed. Discrimination
tests can provide fairly "clean" data but a problem is that they do not relate direction to what matters in
language processing, i.e., the identification of phonetic segments in the service of lexical access. A
categorial oddity test is proposed here that has the virtual of being "phonetically relevant" but, alas, it
is not bias free.
Flege, J. (2002). Interactions between the Native and Second-language Phonetic Systems. In P.
Burmeister, T. Piske and A. Rohde (Eds) An Integrated View of Language Development: Papers in Honor of
Henning Wode. Trier: Wissenschaftlicher Verlag, Pp. 217-244.
Flege, J. (2018) A non-critical period for L2 learning. In Mette Nyvad, M. HejnáHoyen, A.
Jespersen, & M. Sorensen (Eds.) A sound approach to language matters. In Honor of
Ocke-Schwen Bohn. Aarhus University, Denmark: School of Communication and
Culture. [Open Access e-book at Aarhus University Library].

Abstract. Early learners usually enjoy greater success in second-language (L2)
learning than Late learners do. This is often interpreted to mean that the capacity for
L2 learning diminishes after the close of a critical period. However the seeming limits on
Late learners’ success in learning an L2 following immigration, even after years of
regular L2 use in the host country, may not be the unwanted consequence of normal
neurocognitive maturation. It may instead arise from differences in the quantity and
quality of input that Early and Late learners typically receive. This hypothesis was
supported by the research reviewed in this chapter for both L2 speech learning and
some aspects of L2 morphosyntax learning, leading to the proposal that long-term
success in L2 learning is determined probabilistically by a non-critical period defined by
age-related variation in L2 input.