Neural Dynamics of Phonetic Trading Relations for Variable-Rate CV Syllables

The perception of CV syllables exhibits a trading relationship between voice onset time (VOT) of a consonant and duration of a vowel. Percepts of [ba] and [wa] can, for example, depend on the durations of the consonant and vowel segments, with an increase in the duration of the subsequent vowel switching the percept of the preceding consonant from [w] to [b]. A neural model, called PHONET, is proposed to account for these findings. In the model, C and V inputs are filtered by parallel auditory streams that respond preferentially to transient and sustained properties of the acoustic signal, as in vision. These streams are represented by working memories that adjust their processing rates to cope with variable acoustic input rates. More rapid transient inputs can cause greater activation of the transient stream which, in turn, can automatically gain control the processing rate in the sustained stream. An invariant percept obtains when the relative activations of C and V representations in the two streams remain uncha.nged. The trading relation may be simulated as a result of how different experimental manipulations affect this ratio. It is suggested that the brain can use duration of a subsequent vowel to make the [b]/[w] distinction because the speech code is a resonant event that emerges between working mernory activation patterns and the nodes that categorize them.Advanced Research Projects Agency (90-0083); Air Force Office of Scientific Reseearch (F19620-92-J-0225); Pacific Sierra Research Corporation (91-6075-2

Investigating computational models of perceptual attack time

The perceptual attack time (PAT) is the compensation for differing attack components of sounds, in the case of seeking a perceptually isochronous presentation of sounds. It has applications in scheduling and is related to, but not necessarily the same as, the moment of perceptual onset. This paper describes a computational investigation of PAT over a set of 25 synthesised stimuli, and a larger database of 100 sounds equally divided into synthesised and ecological. Ground truth PATs for modeling were obtained by the alternating presentation paradigm, where subjects adjusted the relative start time of a reference click and the sound to be judged. Whilst fitting experimental data from the 25 sound set was plausible, difficulties with existing models were found in the case of the larger test set. A pragmatic solution was obtained using a neural net architecture. In general, learnt schema of sound classification may be implicated in resolving the multiple detection cues evoked by complex sounds

Interference Conditions of the Reconsolidation Process in Humans: The Role of Valence and Different Memory Systems

Following the presentation of a reminder, consolidated memories become reactivated followed by a process of re-stabilization, which is referred to as reconsolidation. The most common behavioral tool used to reveal this process is interference produced by new learning shortly after memory reactivation. Memory interference is defined as a decrease in memory retrieval, the effect is generated when new information impairs an acquired memory. In general, the target memory and the interference task used are the same. Here we investigated how different memory systems and/or their valence could produce memory reconsolidation interference. We showed that a reactivated neutral declarative memory could be interfered by new learning of a different neutral declarative memory. Then, we revealed that an aversive implicit memory could be interfered by the presentation of a reminder followed by a threatening social event. Finally, we showed that the reconsolidation of a neutral declarative memory is unaffected by the acquisition of an aversive implicit memory and conversely, this memory remains intact when the neutral declarative memory is used as interference. These results suggest that the interference of memory reconsolidation is effective when two task rely on the same memory system or both evoke negative valence.Fil: Fernández, Rodrigo Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Bavassi, Mariana Luz. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; ArgentinaFil: Kaczer, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Forcato, Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Pedreira, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentin

Moving beyond Kucera and Francis: a critical evaluation of current word frequency norms and the introduction of a new and improved word frequency measure for American English

Word frequency is the most important variable in research on word processing and memory. Yet, the main criterion for selecting word frequency norms has been the availability of the measure, rather than its quality. As a result, much research is still based on the old Kucera and Francis frequency norms. By using the lexical decision times of recently published megastudies, we show how bad this measure is and what must be done to improve it. In particular, we investigated the size of the corpus, the language register on which the corpus is based, and the definition of the frequency measure. We observed that corpus size is of practical importance for small sizes (depending on the frequency of the word), but not for sizes above 16-30 million words. As for the language register, we found that frequencies based on television and film subtitles are better than frequencies based on written sources, certainly for the monosyllabic and bisyllabic words used in psycholinguistic research. Finally, we found that lemma frequencies are not superior to word form frequencies in English and that a measure of contextual diversity is better than a measure based on raw frequency of occurrence. Part of the superiority of the latter is due to the words that are frequently used as names. Assembling a new frequency norm on the basis of these considerations turned out to predict word processing times much better than did the existing norms (including Kucera & Francis and Celex). The new SUBTL frequency norms from the SUBTLEXUS corpus are freely available for research purposes from http://brm.psychonomic-journals.org/content/supplemental, as well as from the University of Ghent and Lexique Web sites

Pronunciation Understood : How intelligible do you think you are?

This study aims at automatically estimating probability of individual words of Japanese English (JE) being perceived correctly by American listeners and clarifying what kinds of (combinations of) segmental, prosodic, and linguistic errors in the words are more fatal to their correct perception. From a JE speech database, a balanced set of 360 utterances by 90 male speakers are firstly selected. Then, a listening experiment is done where 6 Americans are asked to transcribe all the utterances. Next, using speech and language technology, values of many segmental, prosodic, and linguistic attributes of the words are extracted. Finally, the relation between transcription rate of each word and its attribute values is analyzed by the Classification And Regression Tree (CART) method to predict probability of each of the JE words being transcribed correctly. Performance of the machine prediction is compared with that of the human prediction by four American teachers and three Japanese ones. This method is shown to be comparable to the best American teacher of the four. This paper also describes differences in perceiving intelligibility of the pronunciation between American teachers and Japanese ones

The influences and outcomes of phonological awareness: a study of MA, PA and auditory processing in pre-readers with a family risk of dyslexia

The direct influence of phonological awareness (PA) on reading outcomes has been widely demonstrated, yet PA may also exert indirect influence on reading outcomes through other cognitive variables such as morphological awareness (MA). However, PA's own development is dependent and influenced by many extraneous variables such as auditory processing, which could ultimately impact reading outcomes. In a group of pre-reading children with a family risk of dyslexia and low-risk controls, this study sets out to answer questions surrounding PA's relationship at various grain sizes (syllable, onset/rime and phoneme) with measures of auditory processing (frequency modulation (FM) and an amplitude rise-time task (RT)) and MA, independent of reading experience. Group analysis revealed significant differences between high- and low-risk children on measures of MA, and PA at all grain sizes, while a trend for lower RT thresholds of high-risk children was found compared with controls. Correlational analysis demonstrated that MA is related to the composite PA score and syllable awareness. Group differences on MA and PA were re-examined including PA and MA, respectively, as control variables. Results exposed PA as a relevant component of MA, independent of reading experience

Prosody generation with a neural network

The use of neural networks in speech synthesis has been especially successful in the domain of prosody generation. The approach presented here differs from others in a) the transformation from a simple input to an output vector consisting of different parameters and b) the use of subcorpora that allow specialized networks. The network operates in a prominence-based synthesis system, where prominence is the most important parameter and is, consequently, the input parameter for the network. The output is not yet evaluated formally but the synthetic speech sounds natural and lively