The self-organization of speech sounds

The speech code is a vehicle of language: it defines a set of forms used by a community to carry information. Such a code is necessary to support the linguistic interactions that allow humans to communicate. How then may a speech code be formed prior to the existence of linguistic interactions? Moreover, the human speech code is discrete and compositional, shared by all the individuals of a community but different across communities, and phoneme inventories are characterized by statistical regularities. How can a speech code with these properties form? We try to approach these questions in the paper, using the "methodology of the artificial". We build a society of artificial agents, and detail a mechanism that shows the formation of a discrete speech code without pre-supposing the existence of linguistic capacities or of coordinated interactions. The mechanism is based on a low-level model of sensory-motor interactions. We show that the integration of certain very simple and non-language-specific neural devices leads to the formation of a speech code that has properties similar to the human speech code. This result relies on the self-organizing properties of a generic coupling between perception and production within agents, and on the interactions between agents. The artificial system helps us to develop better intuitions on how speech might have appeared, by showing how self-organization might have helped natural selection to find speech.     

The origin of human multi-modal communication

One reason for the apparent gulf between animal and human communication systems is that the focus has been on the presence or the absence of language as a complex expressive system built on speech. But language normally occurs embedded within an interactional exchange of multi-modal signals. If this larger perspective takes central focus, then it becomes apparent that human communication has a layered structure, where the layers may be plausibly assigned different phylogenetic and evolutionary origins—especially in the light of recent thoughts on the emergence of voluntary breathing and spoken language. This perspective helps us to appreciate the different roles that the different modalities play in human communication, as well as how they function as one integrated system despite their different roles and origins. It also offers possibilities for reconciling the ‘gesture-first hypothesis’ with that of gesture and speech having evolved together, hand in hand—or hand in mouth, rather—as one system.     

Infant‐Directed Communication in Lowland Gorillas (Gorilla gorilla): Do Older Animals Scaffold Communicative Competence in Infants?

Infant-directed speech is a linguistic phenomenon in which adults adapt their language when addressing infants in order to provide them with more salient linguistic information and aid them in language acquisition. Adult-directed language differs from infant-directed language in various aspects, including speech acoustics, syntax, and semantics. The existence of a "gestural motherese" in interaction with infants, demonstrates that not only spoken language but also nonvocal modes of communication can become adapted when infants are recipients. Rhesus macaques are so far the only nonhuman primates where a similar phenomenon to "motherese" has been discovered: the acoustic spectrum of a particular vocalization of adult females may be altered when the addressees are infants. The present paper describes how gorillas adjust their communicative strategies when directing intentional, nonvocal play signals at infants in the sense of a "nonvocal motherese." Animals of ages above infancy use a higher rate of repetitions and sequences of the tactile sensory modality when negotiating play with infants. This indicates that gorillas employ a strategy of infant-specific communication.     

Disorders of System Brain Activity in Children with Motor (Expressive) Alalia

Motor alalia refers to a number of disorders of expressive speech that are caused by the dysfunction of cerebral structures in the period when the formation of the speech system is not complete. This form of speech disorder is considered as a language disorder characterized by a persistent disturbance of the assimilation of a system of linguistic units. The possible cause of deviations in the development of speech function in children is a disproportion in the levels of development of speech structures in the left and right hemispheres, and this temporary dominance is often associated with an increased activity in the right hemisphere. According to the results of electroencephalographic studies, in children aged five to six years, there are two types of changes of the bioelectric potential system interaction of the brain cortex. The disorders of the spatial organization of interregional EEG correlations are more pronounced in either the left or right hemispheres of the brain. Thus, motor alalia can be accompanied either by disturbances in the interaction between Broca’s and Wernicke’s areas of the left hemisphere, or between symmetrical areas of the right hemisphere.     

Language Ideology and Women's Speech: Talking Community in the Northwest Amazon

Taking the Northwest Amazon of Brazil as its example, this article argues for the analytic concept of a "speech culture," combining, but heuristically separating, speech practice and language ideology. In the Northwest Amazon, an ideology of language establishes an equivalence between linguistic performance and descent group belonging. In contrast to the fixed, normative notions of groupness, this article explores the dynamic construction of social relations through women's ritualized wept greeting speech. In these interactions, linguistic differentiation is countered by the experience of a single speech act based upon shared principles with organized participation in and by different linguistic codes. Through the collaborative nature of the speech act a common ground is produced and revealed. The community in this sense emerges as a cultural artifact whose production is largely the work of women. Through these speech interactions—of similar sentiments and meanings across different linguistic codes—women of the Northwest Amazon construct a community of talk. [Keywords: women, laments, language, Amazonia]     

Association Process and Functional Brain Asymmetry

Analysis is presented of word associations produced by subjects with left hemispheric (group 1), right hemispheric (group 2), and bilateral (group 3) speech representation. The strategy for producing extralinguistic responses was found to prevail over the strategy for producing linguistic associations in all subjects, irrespective of their type of speech representation. This strategy was more pronounced in subjects with right hemispheric speech laterality, suggesting a correlation between the generation of extralinguistic associations and functional brain asymmetry. Producing linguistic associations also depended on the type of cerebral organization of speech. The most important linguistic associations are syntagmatic. Syntagmatic associations were more closely related to the lateralization of speech to the left hemisphere. The data are compared to the results of studies of the ontogeny of associative processes.     

Cost and complexity: selection for speech and language

The handicap principle has been applied to a number of different traits in the last three decades, but it is difficult to characterize its record, or even its perceived relevance, when it comes to an important human attribute—spoken language. In some cases, assumptions regarding the energetic cost of speech, and the veracity of linguistically encoded messages, have failed to recognize critical aspects of human development, cognition, and social ecology. In other cases, the fact that speech contains honest (physiological) information, and tends to be used honestly with family and friends, has been overlooked. Speech and language are functionally related but they involve different resources. Individuals can increase the attractiveness of their speech, and of more stylized vocal and verbal performances, without enhancing linguistic structure or content; and they can modify their use of language without significant changes in the physical form of speech. That its production costs are normally low enables speech to be produced extravagantly in bids for status and mating relationships, and in evolution, may have allowed its content—linguistic knowledge and structure—to become complex.     

The speech of reality and the speech of the stage: life, science and art

Word is the most frequent way of communication in the human experience. As a mean of communication it influences the sentence formulation, which ought to be the autochthonous expression of thoughts. The experience teaches us that it is necessary to be a sovereign master of our own thoughts and of sentiments of others. This is one of the fundamental postulates of the communication in the word category. To speak correctly means to think correctly and that, on the other hand, means in the grammatical, lexical and stylistic aspect to be able to create a sentence as a way of getting across the thoughts, ideas and contents of the spirit. The community mentality, the person's characteristics (the temper, the type and the intensity), the education level, the range of the knowledge and the volume of their potentially creative synthesis determine the lexical richness and the amplitude of the use and the application of the language with the aim of establishing a high quality communication with words as a basic mean of that process. Within this context a word has its impressive and expressive dimensions. Its impressive dimension is created by the common reliance on the frequency of the use of some lexical possibilities and their variations. It is an individual characteristic of the spoken and the written output of every person and it also determines the singularities of a person's style, to that extent that it helps to detect the author of a text with a high percentage of accuracy even in the cases where the author is unknown. The expressive value of a word denotes the author's level of thinking depending on the situation in which he uses the words to express his thoughts. In this sense the word is chosen with a different approach for the communication on a friendly or intimate level from an approach used in a communication on the official level or in a relation between the individual and the public. All this affirms the word as a mean that is individually chosen and used for the expression of the speaker's ideas, attitudes and points of view in the communication process, which reveals the characteristics and the speaker's level in all the named aspects of the word value assessment. In the case of evaluation., of the word through the experience of the on-stage speech, that is, the words in the experience of the theatre art, the approach to the value assessment is contrary to the assessment carried out in an everyday, real experience. In the artistic language the words are already given, the sentences are formulated and all this is determined by the author's will and the act of creation. The actor is the interpreter of the author, his ideas along with the characters of the protagonists and the spirit of the action and, therefore, he must gradually master the word to the extent where it seems spontaneous from the point of view of the impressive and expressive categories. It also has to sound similar to the natural speech and its suggestive influence. With this counter-natural direction of the treatment of the given word it is important to reach the level of spontaneity of the expression to an almost documentary form in the overall verbal-scenic-mimic articulation. In this process the life and the art mesh and the art illustrates and defends the life.     

Functional imaging of the auditory processing applied to speech sounds

In this paper, we describe domain-general auditory processes that we believe are prerequisite to the linguistic analysis of speech. We discuss biological evidence for these processes and how they might relate to processes that are specific to human speech and language. We begin with a brief review of (i) the anatomy of the auditory system and (ii) the essential properties of speech sounds. Section 4 describes the general auditory mechanisms that we believe are applied to all communication sounds, and how functional neuroimaging is being used to map the brain networks associated with domain-general auditory processing. Section 5 discusses recent neuroimaging studies that explore where such general processes give way to those that are specific to human speech and language.     

The Evolution of the Exponent of Zipf's Law in Language Ontogeny

It is well-known that word frequencies arrange themselves according to Zipf''s law. However, little is known about the dependency of the parameters of the law and the complexity of a communication system. Many models of the evolution of language assume that the exponent of the law remains constant as the complexity of a communication systems increases. Using longitudinal studies of child language, we analysed the word rank distribution for the speech of children and adults participating in conversations. The adults typically included family members (e.g., parents) or the investigators conducting the research. Our analysis of the evolution of Zipf''s law yields two main unexpected results. First, in children the exponent of the law tends to decrease over time while this tendency is weaker in adults, thus suggesting this is not a mere mirror effect of adult speech. Second, although the exponent of the law is more stable in adults, their exponents fall below 1 which is the typical value of the exponent assumed in both children and adults. Our analysis also shows a tendency of the mean length of utterances (MLU), a simple estimate of syntactic complexity, to increase as the exponent decreases. The parallel evolution of the exponent and a simple indicator of syntactic complexity (MLU) supports the hypothesis that the exponent of Zipf''s law and linguistic complexity are inter-related. The assumption that Zipf''s law for word ranks is a power-law with a constant exponent of one in both adults and children needs to be revised.     

A game theoretical approach to the evolution of structured communication codes

Structured meaning-signal mappings, i.e., mappings that preserve neighborhood relationships by associating similar signals with similar meanings, are advantageous in an environment where signals are corrupted by noise and sub-optimal meaning inferences are rewarded as well. The evolution of these mappings, however, cannot be explained within a traditional language evolutionary game scenario in which individuals meet randomly because the evolutionary dynamics is trapped in local maxima that do not reflect the structure of the meaning and signal spaces. Here we use a simple game theoretical model to show analytically that when individuals adopting the same communication code meet more frequently than individuals using different codes—a result of the spatial organization of the population—then advantageous linguistic innovations can spread and take over the population. In addition, we report results of simulations in which an individual can communicate only with its K nearest neighbors and show that the probability that the lineage of a mutant that uses a more efficient communication code becomes fixed decreases exponentially with increasing K. These findings support the mother tongue hypothesis that human language evolved as a communication system used among kin, especially between mothers and offspring.     

Effects of speech clarity on recognition memory for spoken sentences

Extensive research shows that inter-talker variability (i.e., changing the talker) affects recognition memory for speech signals. However, relatively little is known about the consequences of intra-talker variability (i.e. changes in speaking style within a talker) on the encoding of speech signals in memory. It is well established that speakers can modulate the characteristics of their own speech and produce a listener-oriented, intelligibility-enhancing speaking style in response to communication demands (e.g., when speaking to listeners with hearing impairment or non-native speakers of the language). Here we conducted two experiments to examine the role of speaking style variation in spoken language processing. First, we examined the extent to which clear speech provided benefits in challenging listening environments (i.e. speech-in-noise). Second, we compared recognition memory for sentences produced in conversational and clear speaking styles. In both experiments, semantically normal and anomalous sentences were included to investigate the role of higher-level linguistic information in the processing of speaking style variability. The results show that acoustic-phonetic modifications implemented in listener-oriented speech lead to improved speech recognition in challenging listening conditions and, crucially, to a substantial enhancement in recognition memory for sentences.     

Vowel Hyperarticulation in Parrot-, Dog- and Infant-Directed Speech

ABSTRACT

Vowel triangle area is a phonetic measure of the clarity of vowel articulation. Compared with speech to adults, people hyperarticulate vowels in speech to infants and foreigners but not to pets, despite other similarities in infant- and pet-directed-speech. This suggests that vowel hyperarticulation has a didactic function positively related to the actual, or even the expected, degree of linguistic competence of the audience. Parrots have some degree of linguistic competence yet no studies have examined vowel hyperarticulation in speech to parrots. Here, we compared the speech of 11 adults to another adult, a dog, a parrot, and an infant. A significant linear increase in vowel triangle area was found across the four conditions, showing that the degree of vowel hyperarticulation increased from adult- and dog-directed speech to parrot-directed speech, then to infant-directed speech. This suggests that the degree of vowel hyperarticulation is related to the audience's actual or expected linguistic competence. The results are discussed in terms of the relative roles of speakers' expectations versus listeners' feedback in the production of vowel hyperarticulation; and suggestions for further studies, manipulating speaker expectation and listener feedback, are provided.     

How is linguistic memory accessed? A psychophysiological approach

The role of "subvocalization" during language comprehension, especially reading, is examined. Four arguments against it having a role in accessing memory are erroneous because 1) its latency is much shorter than is conventionally stated; 2) rate of visual information processing is erroneously estimated by failing to distinguish between reading and scanning; 3) covert speech does not disappear in the competent language performer; and 4) the argument that subvocalization is an epiphenomenon is irrelevant. Rather, data support the generalization that covert speech is present during all cognitive functioning and that its specific topography is discriminatively related to the class of phoneme being processed. It is thus inferred that during cognition the speech musculature generates a phonetic code that may function to access linguistic memory. However, since there are also numerous other psychophysiologic events associated with covert speech, a multichannel processing system is hypothesized wherein speech, visual, and kinesthetic modalities interact with the brain. Illustrations are given of how this accessing model is compatible with existing holographic and feature analyzer models of memory. Data are presented that illustrate how phonetically encoded neuromuscular events can be directly measured through psychophysiologic methods. It is hypothesized that cognitive processes are generated when cybernetic neuromuscular circuits selectively interact. Consequently, all components of these neuromuscular circuits serve a function during cognition so that a role for "subvocalization" (a muscular component) cannot be ruled out in an apriori manner.     

Auditory Perception of Voice Signals with Abnormal Sounding in Children

Invariant and noise-proof speech understanding is an important human ability, ensured by several mechanisms of the audioverbal system, which develops parallel to mastering linguistic rules. It is a fundamental problem of speech studies to clarify the mechanisms of this understanding, especially their role in the speech development. The article deals with of the regularities of auditory word recognition in noise by preschool children (healthy and with speech development disorders) and patients with cochlear implants. The authors studied the recognition of words using pictures (by children) and verbal monitoring, when the subjects were stimulated by isolated words with one or all syllables in noise. The study showed that children's ability to perceive distorted words develops in ontogeny and is closely related to the development of mental processes and mastering linguistic rules. The data on patients with cochlear implants also confirmed the key role of the central factors in understanding distorted speech.     

Phonetic Ability and Related Anatomy of the Newborn and Adult Human, Neanderthal Man, and the Chimpanzee

The sounds of human speech make human language a rapid medium of communication through a process of speech "encoding." The presence of sounds like the vowels [a], [i], and [u] makes this process possible. The supralaryngeal vocal tracts of newborn Homo sapiens and chimpanzee are similar and resemble the reconstructed vocal tract of the fossil La Chapelle-aux-Saints Neanderthal man. Vocal tract area functions that were directed toward making best possible approximations to the human vowels [a], [i], and [u], as well as certain consonantal configurations, were modeled by means of a computer program. The lack of these vowels in the phonetic repertories of these creatures, who lack a supralaryngeal pharyngeal region like that of adult Homo sapiens, may be concomitant with the absence of speech encoding and a consequently linguistic ability inferior to modern man.     

The Integration of Prosodic Speech in High Functioning Autism: A Preliminary fMRI Study

Background

Autism is a neurodevelopmental disorder characterized by a specific triad of symptoms such as abnormalities in social interaction, abnormalities in communication and restricted activities and interests. While verbal autistic subjects may present a correct mastery of the formal aspects of speech, they have difficulties in prosody (music of speech), leading to communication disorders. Few behavioural studies have revealed a prosodic impairment in children with autism, and among the few fMRI studies aiming at assessing the neural network involved in language, none has specifically studied prosodic speech. The aim of the present study was to characterize specific prosodic components such as linguistic prosody (intonation, rhythm and emphasis) and emotional prosody and to correlate them with the neural network underlying them.

Methodology/Principal Findings

We used a behavioural test (Profiling Elements of the Prosodic System, PEPS) and fMRI to characterize prosodic deficits and investigate the neural network underlying prosodic processing. Results revealed the existence of a link between perceptive and productive prosodic deficits for some prosodic components (rhythm, emphasis and affect) in HFA and also revealed that the neural network involved in prosodic speech perception exhibits abnormal activation in the left SMG as compared to controls (activation positively correlated with intonation and emphasis) and an absence of deactivation patterns in regions involved in the default mode.

Conclusions/Significance

These prosodic impairments could not only result from activation patterns abnormalities but also from an inability to adequately use the strategy of the default network inhibition, both mechanisms that have to be considered for decreasing task performance in High Functioning Autism.