Low-frequency acoustic modulations generated by the high-frequency portion of the cochlea, noninvasively recorded from the scalp of mice (Mus musculus)

Vocalizations often contain low-frequency modulations of the envelope of a high-frequency sound. The high-frequency portion of the cochlear nerve of mice (Mus musculus) generates a robust phase-locked response to these low-frequency modulations, and it can be easily recorded from the surface of the scalp. The cochlea is most sensitive to envelope modulation frequencies of approximately 500 to 2000 Hz. These responses have detection thresholds that are approximately 10 dB more sensitive than auditory brainstem responses, and they are very sharply tuned. These measurements may provide a nontraumatic means of repeatedly assessing cochlear functions involved in sound localization and perception of vocalizations.     

Early and late mismatch negativity elicited by words and speech-like stimuli in children

In auditory perception the brain's attentional and preattentional mechanisms select certain stimuli for preferential processing and filter out irrelevant input. This study investigated nonattentive auditory processing in children. Event-related potentials (ERPs) provide a means to study neural correlates related to language and speech-sound processing. Mismatch negativity (MMN) is an ERP wave that indicates attention-independent perceptual change detection. In this study cortical ERPs were elicited by complex tones, naturally spoken words, and pseudowords, with each stimulus type containing equal acoustical elements. Tones elicited a bifurcated mismatch negativity (MMN), with early MMN (peaking at 150-200 ms) being more dominant. On the other hand, words elicited a strong late MMN, peaking at about 400-450 ms after stimulus onset. The MMN wave form was significantly weaker for pseudowords than for words. The late MMN wave, especially for word differences, was found to reflect summating MMN generators and memory trace formation on gestalt bases. Results suggest that the auditory processing, even nonattended, is highly associated with the cognitive meaning of the stimuli.     

The time course of neural changes underlying auditory perceptual learning

Improvement in perception takes place within the training session and from one session to the next. The present study aims at determining the time course of perceptual learning as revealed by changes in auditory event-related potentials (ERPs) reflecting preattentive processes. Subjects were trained to discriminate two complex auditory patterns in a single session. ERPs were recorded just before and after training, while subjects read a book and ignored stimulation. ERPs showed a negative wave called mismatch negativity (MMN)—which indexes automatic detection of a change in a homogeneous auditory sequence—just after subjects learned to consciously discriminate the two patterns. ERPs were recorded again 12, 24, 36, and 48 h later, just before testing performance on the discrimination task. Additional behavioral and neurophysiological changes were found several hours after the training session: an enhanced P2 at 24 h followed by shorter reaction times, and an enhanced MMN at 36 h. These results indicate that gains in performance on the discrimination of two complex auditory patterns are accompanied by different learning-dependent neurophysiological events evolving within different time frames, supporting the hypothesis that fast and slow neural changes underlie the acquisition of improved perception.     

汉语口语韵律的作用及其神经机制

汉语是一种声调语言, 在口语韵律表达中存在独特的特点。本项目利用汉语不同于非声调语言的特点, 探讨已有研究中尚未澄清的问题, 即汉语声调在早期自动加工中对语义激活的作用, 以及在不同认知阶段中, 汉语声调和语调加工的神经机制。这些问题是当前的研究热点, 但仍存在着各种分歧和激烈的争论。本项目拟采用ERP方法, 结合LORETA源定位技术, 通过不同的实验范式考察以下内容：(1)在早期自动加工过程中, 汉语声调对词汇语义激活的作用; (2)在早期阶段, 汉语声调和语调加工的大脑激活模式; (3)在晚期阶段, 汉语声调和语调加工的大脑激活模式。对这些问题的考察将有助于澄清当前的激烈争论, 拓展以往基于非声调语言研究建立的口语加工理论的适用范围, 为完善言语认知加工的理论模型提供新的实验证据。     

On the perception of speech from time-varying acoustic information: contributions of amplitude variation

The cyclic variation in the energy envelope of the speech signal results from the production of speech in syllables. This acoustic property is often identified as a source of information in the perception of syllable attributes, though spectral variation can also provide this information reliably. In the present study of the relative contributions of the energy and spectral envelopes in speech perception, we employed sinusoidal replicas of utterances, which permitted us to examine the roles of these acoustic properties in establishing or maintaining time-varying perceptual coherence. Three experiments were carried out to assess the independent perceptual effects of variation in sinusoidal amplitude and frequency, using sentence-length signals. In Experiment 1, we found that the fine grain of amplitude variation was not necessary for the perception of segmental and suprasegmental linguistic attributes; in Experiment 2, we found that amplitude was nonetheless effective in influencing syllable perception, and that in some circumstances it was crucial to segmental perception; in Experiment 3, we observed that coarse-grain amplitude variation, above all, proved to be extremely important in phonetic perception. We conclude that in perceiving sinusoidal replicas, the perceiver derives much from following the coherent pattern of frequency variation and gross signal energy, but probably derives rather little from tracking the precise details of the energy envelope. These findings encourage the view that the perceiver uses time-varying acoustic properties selectively in understanding speech.     

Atypical central auditory speech-sound discrimination in children who stutter as indexed by the mismatch negativity

PurposeRecent theoretical conceptualizations suggest that disfluencies in stuttering may arise from several factors, one of them being atypical auditory processing. The main purpose of the present study was to investigate whether speech sound encoding and central auditory discrimination, are affected in children who stutter (CWS).MethodsParticipants were 10 CWS, and 12 typically developing children with fluent speech (TDC). Event-related potentials (ERPs) for syllables and syllable changes [consonant, vowel, vowel-duration, frequency (F0), and intensity changes], critical in speech perception and language development of CWS were compared to those of TDC.ResultsThere were no significant group differences in the amplitudes or latencies of the P1 or N2 responses elicited by the standard stimuli. However, the Mismatch Negativity (MMN) amplitude was significantly smaller in CWS than in TDC. For TDC all deviants of the linguistic multifeature paradigm elicited significant MMN amplitudes, comparable with the results found earlier with the same paradigm in 6-year-old children. In contrast, only the duration change elicited a significant MMN in CWS.ConclusionsThe results showed that central auditory speech-sound processing was typical at the level of sound encoding in CWS. In contrast, central speech-sound discrimination, as indexed by the MMN for multiple sound features (both phonetic and prosodic), was atypical in the group of CWS. Findings were linked to existing conceptualizations on stuttering etiology.Educational objectives: The reader will be able (a) to describe recent findings on central auditory speech-sound processing in individuals who stutter, (b) to describe the measurement of auditory reception and central auditory speech-sound discrimination, (c) to describe the findings of central auditory speech-sound discrimination, as indexed by the mismatch negativity (MMN), in children who stutter.     

2~4岁普通话儿童前注意阶段的声调感知机制

以MMN、p-MMR作为汉语词汇声调感知的神经关联物,探究2~4岁汉语普通话儿童前注意阶段对声调刺激的失匹配响应,关注范畴信息和偏差大小两个因素对儿童感知水平的影响。结果显示:在范畴间大偏差条件下(T1/T3),诱发明显的MMN;在范畴内或小偏差条件下(T3a/T3、T3b/T3、T2/T3),都未诱发显著的MMR。表明:2~4岁普通话儿童正处于声调感知能力的发展过程中,音位信息和声学信息共同影响其声调感知。     

Auditory perception of temporal and spectral events in patients with focal left and right cerebral lesions

The auditory perception of temporal and spectral information was studied in subjects with lesions in the temporoparietal region of the left (LH group), or right (RH group) hemisphere (n = 5 in each group) and in five normal controls. The temporal tasks included gap detection and two complex pattern perception tasks in which subjects had to identify the placement of the two closest tones (separated by the shortest interval) within a sequence of six tones. The spectral tasks involved pitch matching and frequency discrimination. The results showed a "double dissociation": (1) the LH group was impaired in their ability to perceive temporal information, but the perception of spectral information was normal, and (2) the RH group was impaired in their ability to perceive spectral information, but the perception of temporal information was normal. The findings are consistent with the notion that temporal processing is a function of left-hemisphere structures and that spectral processing is a function of right-hemisphere structures.     

Auditory color constancy: Calibration to reliable spectral properties across nonspeech context and targets

Brief experience with reliable spectral characteristics of a listening context can markedly alter perception of subsequent speech sounds, and parallels have been drawn between auditory compensation for listening context and visual color constancy. In order to better evaluate such an analogy, the generality of acoustic context effects for sounds with spectral-temporal compositions distinct from speech was investigated. Listeners identified nonspeech sounds—extensively edited samples produced by a French horn and a tenor saxophone—following either resynthesized speech or a short passage of music. Preceding contexts were “colored” by spectral envelope difference filters, which were created to emphasize differences between French horn and saxophone spectra. Listeners were more likely to report hearing a saxophone when the stimulus followed a context filtered to emphasize spectral characteristics of the French horn, and vice versa. Despite clear changes in apparent acoustic source, the auditory system calibrated to relatively predictable spectral characteristics of filtered context, differentially affecting perception of subsequent target nonspeech sounds. This calibration to listening context and relative indifference to acoustic sources operates much like visual color constancy, for which reliable properties of the spectrum of illumination are factored out of perception of color.     

Attention modulates somatosensory influences in passive speech listening

Previous studies showed that manipulating the speech production system influenced speech perception. This influence was mediated by task difficulty, listening conditions, and attention. In the present study we investigated the specificity of a somatosensory manipulation – a spoon over the tongue – in passive listening. We measured the mismatch negativity (MMN) while participants listened to vowels that differ in their articulation – the tongue height – and familiarity – native and unknown vowels. The same participants heard the vowels in a spoon and no-spoon block. The order of the blocks was counterbalanced across participants. Results showed no effect of the spoon. Instead, starting with the spoon enhanced the MMN amplitude. A second experiment showed the same MMN enhancement for starting with a somatosensory manipulation applied to a non-articulator – the hand. This result suggests that starting a study with a somatosensory manipulation raises attention to the task.     

Brain mechanisms involved in angry prosody change detection in school-age children and adults,revealed by electrophysiology

Voices transmit social signals through speech and/or prosody. Emotional prosody conveys key information about the emotional state of a speaker and is thus a crucial cue that one has to detect in order to develop efficient social communication. Previous studies in adults reported different brain responses to emotional than to neutral prosodic deviancy. The aim of this study was to characterize such specific emotional deviancy effects in school-age children. The mismatch negativity (MMN) and P3a evoked potentials, reflecting automatic change detection and automatic attention orienting, respectively, were obtained for neutral and emotional angry deviants in both school-age children (n = 26) and adults (n = 14). Shorter latencies were found for emotional than for neutral preattentional responses in both groups. However, whereas this effect was observed on the MMN in adults, it appeared in an early discriminative negativity preceding the MMN in children. A smaller P3a amplitude was observed for the emotional than for the neutral deviants at all ages. Overall, the brain responses involved in specific emotional change processing are already present during childhood, but responses have not yet reached an adult pattern. We suggest that these processing differences might contribute to the known improvement of emotional prosody perception between childhood and adulthood.     

汉语普通话声调感知的老年化效应：来自ERP的证据

研究考察汉语普通话老年人前注意阶段声调感知状况, 探究是否存在领域特殊的老年化。运用事件相关电位技术, 采用被动oddball范式诱发MMN回应, 控制领域一般性因素的影响。结果显示涉及范畴变化的声调和非语音音调诱发MMN强度衰减, 不涉及范畴变化的声调诱发MMN强度未衰退。研究结果表明在前注意阶段, 在特定汉语普通话声调范畴知识加工能力上存在领域特殊的衰退, 而不涉及母语音位知识的声调的感知存在领域特殊的一定程度的保留, 这一保留与时间维度上补偿机制的调用有关。受补偿机制调节, 语言加工呈现出衰退或保留等不同的老年化进程。     

Single-band amplitude demodulation of Müller-Lyer illusion images

The perception of the Müller-Lyer illusion has previously been explained as a result of visual low band-pass spatial filtering, although, in fact, the illusion persists in band-pass and high-pass filtered images without visible low-spatial frequencies. A new theoretical framework suggests that our perceptual experience about the global spatial structure of an image corresponds to the amplitude modulation (AM) component (or its magnitude, also called envelope) of its AM-FM (alternatively, AM-PM) decomposition. Because demodulation is an ill-posed problem with a non-unique solution, two different AM-FM demodulation algorithms were applied here to estimate the envelope of images of Müller-Lyer illusion: the global and exact Daugman and Downing (1995) AMPM algorithm and the local and quasi-invertible Maragos and Bovik (1995) DESA. The images used in our analysis include the classic configuration of illusion in a variety of spatial and spatial frequency content conditions. In all cases, including those of images for which visual low-pass spatial filtering would be ineffective, the envelope estimated by single-band amplitude demodulation has physical distortions in the direction of perceived illusion. It is not plausible that either algorithm could be implemented by the human visual system. It is shown that the proposed second order visual model of pre-attentive segregation of textures (or "back-pocket" model) could recover the image envelope and, thus, explain the perception of this illusion even in Müller-Lyer images lacking low spatial frequencies.     

The auditory sensory memory trace decays rapidly in newborns

The present study investigated the temporal dynamics of auditory sensory memory in newborns as reflected by the mismatch negativity (MMN), a preattentive electric change-detection response. MMN was obtained from 24 full-term healthy newborns who were either awake or asleep (quiet or active sleep) during the experiments. Stimuli were 1,000 Hz tones (standards) that were occasionally replaced by 1,100 Hz tones (deviants). The constant stimulus onset asynchrony (SOA) was, in separate blocks, either 450, 800, or 1,500 ms. A prominent MMN was obtained at the 800 ms SOA in all three sleep or waking states, whereas no MMN occurred at 450 and 1,500 ms SOAs. In view of the fact that in adults MMN is elicited even with a 10s SOA, these results imply that the time span of auditory memory is considerably shorter in neonates than in adults and 8-12-year-old children.     

The Effect of Language Immersion Education on the Preattentive Perception of Native and Non-native Vowel Contrasts

Proficiency in a second language (L2) may depend upon the age of exposure and the continued use of the mother tongue (L1) during L2 acquisition. The effect of early L2 exposure on the preattentive perception of native and non-native vowel contrasts was studied by measuring the mismatch negativity (MMN) response from 14-year-old children. The test group consisted of six Finnish children who had participated in English immersion education. The control group consisted of eight monolingual Finns. The subjects were presented with Finnish and English synthetic vowel contrasts. The aim was to see whether early exposure had resulted in the development of a new language-specific memory trace for the contrast phonemically irrelevant in L1. The results indicated that only the contrast with the largest acoustic distance elicited an MMN response in the Bilingual group, while the Monolingual group showed a response also to the native contrast. This may suggest that native-like memory traces for prototypical vowels were not formed in early language immersion.     

Toward an electrocortical biomarker of cognition for newborn infants

The event-related potential (ERP) effect of mismatch negativity (MMN) was the first electrophysiological probe to evaluate cognitive processing (change detection) in newborn infants. Initial studies of MMN predicted clinical utility for this measure in identification of infants at risk for developmental cognitive deficits. These predictions have not been realized. We hypothesized that in sleeping newborn infants, measures derived from wavelet assessment of power in the MMN paradigm would be more robust markers of the brain's response to stimulus change than the ERP-derived MMN. Consistent with this premise, we found increased power in response to unpredictable and infrequent tones compared to frequent tones. These increases were present at multiple locations on the scalp over a range of latencies and frequencies and occurred even in the absence of an ERP-derived MMN. There were two predominant effects. First, theta band power was elevated at middle and late latencies (200 to 600 ms), suggesting that neocortical theta rhythms that subserve working memory in adults are present at birth. Second, late latency (500 ms) increased power to the unpredictable and infrequent tones was observed in the beta and gamma bands, suggesting that oscillations involved in adult cognition are also present in the neonate. These findings support the expectation that frequency dependent measures, such as wavelet power, will improve the prospects for a clinically useful test of cortical function early in the postnatal period.     

/n/-/l/音位合并现象的神经机制：来自MMN的证据

采用ERP技术,比较音位合并者与非音位合并者辨别合并音位/n/-/l/的脑电和行为反应。结果发现,非音位合并者在注意前阶段展现了显著的MMN;而音位合并者没有展现MMN,但在晚期展现了一个显著的负波。行为实验发现,相比于音位合并者,非音位合并者在分辨/n/-/l/时正确率更高,反应时更短。这些结果表明：两组被试区分/n/-/l/的能力在早期自动加工阶段就已经有了显著的差异。方言经验可能降低了音位合并者在听觉感觉加工阶段检测合并音位差异的敏感度。     

Behavioral and electrophysiological evidence for the impact of regional variation on phoneme perception

This event-related potential (ERP) study examined the impact of phonological variation resulting from a vowel merger on phoneme perception. The perception of the /e/-/ε/ contrast which does not exist in Southern French-speaking regions, and which is in the process of merging in Northern French-speaking regions, was compared to the /ø/-/y/ contrast, which is stable in all French-speaking regions. French-speaking participants from Switzerland for whom the /e/-/ε/ contrast is preserved, but who are exposed to different regional variants, had to perform a same-different task. They first heard four phonemically identical but acoustically different syllables (e.g., /be/-/be/-/be/-/be/), and then heard the test syllable which was either phonemically identical to (/be/) or phonemically different from (/bε/) the preceding context stimuli. The results showed that the unstable /e/-/ε/ contrast only induced a mismatch negativity (MMN), whereas the /ø/-/y/ contrast elicited both a MMN and electrophysiological differences on the P200. These findings were in line with the behavioral results in which responses were slower and more error-prone in the /e/-/ε/ deviant condition than in the /ø/-/y/ deviant condition. Together these findings suggest that the regional variability in the speech input to which listeners are exposed affects the perception of speech sounds in their own accent.     

Brief pitch-priming facilitates infants’ discrimination of pitch-evoking noise: Evidence from event-related potentials

Pitch is derived by the auditory system through complex spectrotemporal processing. Pitch extraction is thought to depend on both spectral cues arising from lower harmonics that are resolved by cochlear filters in the inner ear, and on temporal cues arising from the pattern of action potentials contained in the cochlear output. Adults are capable of extracting pitch in the absence of robust spectral cues, taking advantage of the temporal cues that remain. However, recent behavioral evidence suggests that infants have difficulty discriminating between stimuli with different pitches when resolvable spectral cues are absent. In the current experiments, we used the mismatch negativity (MMN) component of the event related potential derived from electroencephalographic (EEG) recordings to examine a cortical representation of pitch discrimination for iterated rippled noise (IRN) stimuli in 4- and 8-month-old infants. IRN stimuli are pitch-evoking sounds generated by repeatedly adding a segment of white noise to itself at a constant delay. We created IRN stimuli (delays of 5 and 6 ms creating pitch percepts of 200 and 167 Hz) and high-pass filtered them to remove all resolvable spectral pitch cues. In experiment 1, we did not find EEG evidence that infants could detect the change in the pitch of these IRN stimuli. However, in Experiment 2, after a brief period of pitch-priming during which we added a sine wave component to the IRN stimulus at its perceived pitch, infants did show significant MMN in response to pitch changes in the IRN stimuli with sine waves removed. This suggests that (1) infants can use temporal cues to process pitch, although such processing is not mature and (2) that a short amount of pitch-priming experience can alter pitch representations in auditory cortex during infancy.     

Input to verbal working memory: Preattentive construction of the central speech representation

Working memory uses central sound representations as an informational basis. The central sound representation is the temporally and feature-integrated mental representation that corresponds to phenomenal perception. It is used in (higher-order) mental operations and stored in long-term memory. In the bottom-up processing path, the central sound representation can be probed at the level of auditory sensory memory with the mismatch negativity (MMN) of the event-related potential. The present paper reviews a newly developed MMN paradigm to tap into the processing of speech sound representations. Preattentive vowel categorization based on F1-F2 formant information occurs in speech sounds and complex tones even under conditions of high variability of the auditory input. However, an additional experiment demonstrated the limits of the preattentive categorization of language-relevant information. It tested whether the system categorizes complex tones containing the F1 and F2 formant components of the vowel /a/ differently than six sounds with nonlanguage-like F1-F2 combinations. From the absence of an MMN in this experiment, it is concluded that no adequate vowel representation was constructed. This shows limitations of the capability of preattentive vowel categorization.