Auditory mismatch negativity for speech sound contrasts is modulated by language context.

Auditory mismatch negativity is known to reflect language experience. This study wants to clarify whether this effect is dependent on language context. We compared German subjects' magnetic mismatch negativity in response to a non-native speech contrast presented with and without the context of a native contrast. The presence of the native contrast abolished the response to the nonnative sound at the left hemisphere and reduced the right-sided response. A significant context effect set in 170 ms after stimulus onset. As a control, the native contrast was increased by the context. This suggests that the auditory system adapts to the language context and modulates speech processing at early stages of information processing. This may facilitate elevated concentration on acoustic details that are linguistically relevant.

A magnetoencephalographic study on auditory processing of native and nonnative fricative contrasts in Polish and German listeners.

Linguistic experience shapes auditory processing of speech sounds as indicated by the mismatch negativity (MMN). In the current study, magnetic mismatch fields (MMNm) in response to native and nonnative fricative-vowel syllables were recorded, using whole-head magnetoencephalography (MEG). Earlier difference waves were enhanced in the left hemisphere in native listeners for fricatives with rather subtle acoustic differences in frication and pronounced acoustic differences in the transition to the vowel. For nonnative subjects, difference waves were at first stronger in the right hemisphere for these contrasts. Left hemispheric MMNms only occurred later in nonnative participants. The results are discussed in relation to previous studies suggesting lateralization of speech sound processing.

When "AA" is long but "A" is not short: speakers who distinguish short and long vowels in production do not necessarily encode a short-long contrast in their phonological lexicon.

In some languages (such as Dutch), speakers produce duration differences between vowels, but it is unclear whether they also encode short versus long speech sounds into different phonological categories. To examine whether they have abstract representations for 'short' versus 'long' contrasts, we assessed Dutch listeners' perceptual sensitivity to duration in two vowel qualities: [a] and [ɑ], as in the words maan 'moon' and man 'man,' which are realized with long and short duration respectively. If Dutch represents this phonetic durational difference as a 'short'-'long' contrast in its phonology, duration changes in [a] and [ɑ] should elicit similar neural responses [specifically, the mismatch negativity (MMN)]. However, we found that duration changes evoked larger MMN amplitude for [a] than for [ɑ]. This finding indicates that duration is phonemically relevant for the maan-vowel that is represented as 'long,' while it is not phonemically specified for the man-vowel. We argue that speakers who in speech production distinguish a given vowel pair on the basis of duration may not necessarily encode this durational distinction as a binary 'short'-'long' contrast in their phonological lexicon.

Pre-attentive sensitivity to vowel duration reveals native phonology and predicts learning of second-language sounds.

In some languages (e.g. Czech), changes in vowel duration affect word meaning, while in others (e.g. Spanish) they do not. Yet for other languages (e.g. Dutch), the linguistic role of vowel duration remains unclear. To reveal whether Dutch represents vowel length in its phonology, we compared auditory pre-attentive duration processing in native and non-native vowels across Dutch, Czech, and Spanish. Dutch duration sensitivity patterned with Czech but was larger than Spanish in the native vowel, while it was smaller than Czech and Spanish in the non-native vowel. An interpretation of these findings suggests that in Dutch, duration is used phonemically but it might be relevant for the identity of certain native vowels only. Furthermore, the finding that Spanish listeners are more sensitive to duration in non-native than in native vowels indicates that a lack of duration differences in one's native language could be beneficial for second-language learning.

Language experience modulates weighting of acoustic cues for vowel perception: an event-related potential study.

In behavioral tasks, previous research has found that advanced Spanish learners of Dutch rely on duration cues to distinguish Dutch vowels, while Dutch listeners rely on spectral cues. This study tested whether language-specific cue weighting is reflected in preattentive processing. The mismatch negativity (MMN) of Dutch and Spanish participants was examined in response to spectral and duration cues in Dutch vowels. The MMN at frontal and mid sites was weaker and peaked later at Fz for Spanish than for Dutch listeners for the spectrally cued contrasts, whereas both groups responded similarly to the duration cue. In line with overt categorization behavior, these MMN data indicate that preattentive cue weighting depends on the listeners' language experience.

Masked auditory feedback affects speech motor learning of a plosive duration contrast.

Adult speakers have developed precise forward models of articulation for their native language and seem to rely less on auditory sensory feedback. However, for learning of the production of new speech sounds, auditory perception provides a corrective signal for motor control. We assessed adult German speakers' speech motor learning capacity in the absence of auditory feedback but with clear somatosensory information. Learners were presented with a nonnative singleton-geminate duration contrast of voiceless, unaspirated bilabial plosives /p/ vs. /pp/ which is present in Italian. We found that the lack of auditory feedback had no immediate effect but that deviating productions emerged during the course of learning. By the end of training, speakers with masked feedback produced strong lengthening of segments and showed more variation on their production than speakers with normal auditory feedback. Our findings indicate that auditory feedback is necessary for the learning of precise coordination of articulation even if somatosensory feedback is salient.