Functional neuroimaging of speech perception in infants

Human infants begin to acquire their native language in the first months of life. To determine which brain regions support language processing at this young age, we measured with functional magnetic resonance imaging the brain activity evoked by normal and reversed speech in awake and sleeping 3-month-old infants. Left-lateralized brain regions similar to those of adults, including the superior temporal and angular gyri, were already active in infants. Additional activation in right prefrontal cortex was seen only in awake infants processing normal speech. Thus, precursors of adult cortical language areas are already active in infants, well before the onset of speech production.     

1Localization effects with steady thermal noise in one ear and pulsed thermal noise in the other

When the duration or repetition rate of pulses in the left ear is increased, while steady, in-phase, thermal noise sounds in the right ear, the pulses are heard to move toward the median plane. At still longer durations (for a given repetition rate) the loudness of noise on the right diminishes, until finally all sound is localized at the median plane.     

Speech perception in infants

Discriminiationi of synthetic speech sounds was studied in 1- and 4-month-old infants. The speech sounds varied along an acoustic dimension previously shown to cue phonemic distinctions among the voiced and voiceless stop consonants in adults. Discriminability was measured by an increase in conditioned response rate to a second speech sound after habituation to the first speech sound. Recovery from habituation was greater for a given acoustic difference when the two stimuli were from different adult phonemic categories than when they were from the same category. The discontinuity in discrimination at the region of the adult phonemic boundary was taken as evidence for categorical perception.     

Human brain: left-right asymmetries in temporal speech region

We have found marked anatomical asymmetries between tile upper surfaces of the human right and left temporal lobes. The planum temporale (the area behind Hesch's gyrus) is larger on the left in 65 percent of brains; on the right it is larger in only 11 percent. The left planum is on the average one-third longer than the planum. This area makes up part of the temporal speech cortex, whose importance is well established on the basis of both anatomical findings in aphasic patients ans cortical stimulation at operation.     

Sound Playback Experiments with Southern Right Whales (Eubalaena australis)

A variety of sound recordings were played to southern right whales. Whales approached the loudspeaker and made frequent sounds in response to recordings of other southern right whales, but swam away and made relatively few sounds in response to playbacks of water noise, 200-hertz tones, and humpback whale sounds. Thus it appears that southern right whales can differentiate between con-specific sounds and other sounds.     

Auditory induction: perceptual synthesis of absent sounds

Within certain auditory patterns, fainter sounds may be "heard" clearly when replaced by louder sounds having appropriate spectral compositions. This auditory induction of fainter by louder sounds can cancel the perceptual effects of masking. Phonemic restorations, which have been reported previously, appear to be a specialized application to speech of the much broader phenomenon of auditory induction. The rules governing auditory induction indicate that it helps maintain stable auditory perception in our frequently noisy environment.     

Is face processing species-specific during the first year of life?

Between 6 and 10 months of age, the infant's ability to discriminate among native speech sounds improves, whereas the same ability to discriminate among foreign speech sounds decreases. Our study aimed to determine whether this perceptual narrowing is unique to language or might also apply to face processing. We tested discrimination of human and monkey faces by 6-month-olds, 9-month-olds, and adults, using the visual paired-comparison procedure. Only the youngest group showed discrimination between individuals of both species; older infants and adults only showed evidence of discrimination of their own species. These results suggest that the "perceptual narrowing" phenomenon may represent a more general change in neural networks involved in early cognition.     

Infant intermodal speech perception is a left-hemisphere function

Prelinguistic infants recognized structural correspondences in acoustic and optic properties of synchronized, naturally spoken disyllables, but did so only when they were looking to their right sides. This result suggests that intermodal speech perception is facilitated by rightward orientation of attention and subserved by the left hemisphere.     

Restoration of auditory nerve synapses in cats by cochlear implants

Congenital deafness results in abnormal synaptic structure in endings of the auditory nerve. If these abnormalities persist after restoration of auditory nerve activity by a cochlear implant, the processing of time-varying signals such as speech would likely be impaired. We stimulated congenitally deaf cats for 3 months with a six-channel cochlear implant. The device used human speech-processing programs, and cats responded to environmental sounds. Auditory nerve fibers exhibited a recovery of normal synaptic structure in these cats. This rescue of synapses is attributed to a return of spike activity in the auditory nerve and may help explain cochlear implant benefits in childhood deafness.     

ADDRESS OF COL. GARRICK MALLERY,U. S. ARMY

It may be conceded that after man had all his present faculties, he did not choose between the adoption of voice and gesture, and never with those faculties, was in a state where the one was used, to the absolute exclusion of the other. The epoch, however, to which our speculations relate is that in which he had not reached the present symmetric development of his intellect and of his bodily organs, and the inquiry is: Which mode of communication was earliest adopted to his single wants and informed intelligence? With the voice he could imitate distinictively but few sounds of nature, while with gesture he could exhibit actions, motions, positions, forms, dimensions, directions and distances, with their derivations and analogues. It would seem from this unequal division of capacity that oral speech remained rudimentary long after gesture had become an efficient mode of communication. With due allowance for all purely imitative sounds, and for the spontaneous action of vocal organs under excitement, it appears that the connection between ideas and words is only to be explained by a compact between speaker and hearer which supposes the existence of a prior mode of communication. This was probably by gesture. At least we may accept it as a clew leading out of the labyrinth of philological confusion, and regulating the immemorial quest of man's primitive speech.     

Auditory evoked potentials during speech perception

Neural responses evoked by the same binaural speech signal were recorded from ten right-handed subjects during two auditory identification tasks. One task required analysis of acoustic parameters important for making a linguistic distinction, while the other task required analysis of an acoustic parameter which provides no linguistic information at the phoneme level. In the time interval between stimulus onset and the subjects' identification responses, evoked potentials from the two tasks were significantly different over the left hemisphere but identical over the right hemisphere. These results indicate that different neural events occur in the left hemisphere during analysis of linguistic versus nonlinguistic parameters of the same acoustic signal.     

Hemispheric asymmetry of electrocortical responses to speech stimuli

In a group of normal adults, averaged cortical evoked responses to natural speech stimuli were recorded from scalp electrodes placed symmetrically over the two cerebral hemispheres at frontal, Rolandic, and temporoparietal leads. The amplitude of the most prominent component was consistently larger in left hemisphere derivations, with the major hemisphere difference observed in the temporoparietal records. These electrophysiological measures may be sensitive indicators of hemispheric specialization of function.     

Forms of Sounds as Shown on an Oscilloscope by Roulette Figures

It has been found that with an oscilloscope driven through a simple network of two resistors and two capacitors it is possible to produce recognizable pictures from speech sounds. These pictures thus become a natural phonetic alphabet, with which both standard pronunciation and the nuances of dialect and accent can be represented. While a given speech sound has certain invariant characteristics, it has also an overlay of accent, which can be represented in the alphabetic character. It is suggested that the technique may be useful in teaching deaf children to speak.     

Neurochemical correlate of a spatial preference in rats

Spatial (left or right) preferences were determined for rats given foot shock in a T-maze. The animals were killed, and left and right striata were assayed separately for dopamine and left and right teldiencephalic regions were assayed for norepinephrine. Dopamine content was significantly higher (by 12 percent) in the striata contralateral to rats' side preferences than in the ipsilateral striata; there was no such difference for teldiencephalic norepinephrine. The small asymmetry in striatal dopamine content is not due to any learning- or stress-related change induced by the testing procedure but is probably inherent in normal rats. Some spatial behavior appears to be the manifestation of a normal and specific difference in the activity of left and right nigrostriatal systems.     

Human voice recognition depends on language ability

The ability to recognize people by their voice is an important social behavior. Individuals differ in how they pronounce words, and listeners may take advantage of language-specific knowledge of speech phonology to facilitate recognizing voices. Impaired phonological processing is characteristic of dyslexia and thought to be a basis for difficulty in learning to read. We tested voice-recognition abilities of dyslexic and control listeners for voices speaking listeners' native language or an unfamiliar language. Individuals with dyslexia exhibited impaired voice-recognition abilities compared with controls only for voices speaking their native language. These results demonstrate the importance of linguistic representations for voice recognition. Humans appear to identify voices by making comparisons between talkers' pronunciations of words and listeners' stored abstract representations of the sounds in those words.     

用负熵最大化小波实现强噪声下的语音识别

针对高噪环境下语音识别的困难,以独立分量分析和小波理论为基础,提出一种负熵最大化小波语音降噪预处理新方法,对不同种类和不同输入信噪比的噪声设计了试验,结果表明在低输入信噪比情况下本方法的优越性,此结论对高噪环境下的信号分析和语音识别具有重要意义。     

教师正确的吐字发音方法探析

教师只有掌握正确的吐字发音方法，做到字正腔圆，利用普通话语音圆润悦耳的音色和抑扬顿挫的音调讲课，才能收到以声传情，声情并茂的表达效果，使学生在学习知识抽时，得到语言美的享受。     

Aspects of a cognitive neuroscience of mental imagery

Although objects in visual mental images may seem to appear all of a piece, when the time to form images is measured this introspection is revealed to be incorrect; objects in images are constructed a part at a time. Studies with split-brain patients and normal subjects reveal that two classes of processes are used to form images--ones that activate stored memories of the appearances of parts and ones that arrange parts into the proper configuration. Some of the processes used to arrange parts are more effective in the left cerebral hemisphere and some are more effective in the right cerebral hemisphere; the notion that mental images are the product of right hemisphere activity is an oversimplification.     

试论农民代言人出现的背景及其对农民话语权回归的作用

介绍了在目前我国农民存在着制度缺陷型、能力欠缺型及信息断裂型话语缺失的背景下,一些非农精英人士自觉自愿承担起农民代言人的角色,为推动"三农"问题的解决发挥了巨大的作用。并提出农民代言人的终极使命应该是帮助农民完全掌握与其他阶层平等的话语权,实现从"代农民言"到"农民自己言"的转变。     

Asymmetric cochlear processing mimics hemispheric specialization

Otoacoustic emissions or OAEs (reflections of cochlear energy produced during the processing of sound) were measured in response to two types of stimuli, rapid clicks and sustained tones, in each ear of neonates. OAEs were larger to tones when elicited in the left ear and to clicks when elicited in the right. This finding is similar to those of enhanced processing of tones in right auditory cortical areas and of rapid stimuli on the left, given strong crossed connections from ear to brain. These findings indicate that processing at the level of the ear may facilitate lateralization of auditory function in the brain.