Phonetics/Phonology

Acceptability judgments are reports of a speaker’s or signer’s subjective sense of the well-formedness, nativeness, or naturalness of (novel) linguistic forms. Their value comes in providing data about the nature of the human capacity to generalize beyond linguistic forms previously encountered in language comprehension. For this reason, acceptability judgments are often also called grammaticality judgments (particularly in syntax), although unlike the theory-dependent notion of grammaticality, acceptability is accessible to consciousness. While acceptability judgments have been used to test grammatical claims since ancient times, they became particularly prominent with the birth of generative syntax. Today they are also widely used in other linguistic schools (e.g., cognitive linguistics) and other linguistic domains (pragmatics, semantics, morphology, and phonology), and have been applied in a typologically diverse range of languages. As psychological responses to linguistic stimuli, acceptability judgments are experimental data. Their value thus depends on the validity of the experimental procedures, which, in their traditional version (where theoreticians elicit judgments from themselves or a few colleagues), have been criticized as overly informal and biased. Traditional responses to such criticisms have been supplemented in recent years by laboratory experiments that use formal psycholinguistic methods to collect and quantify judgments from nonlinguists under controlled conditions. Such formal experiments have played an increasingly influential role in theoretical linguistics, being used to justify subtle judgment claims or new grammatical models that incorporate gradience or lexical influences. They have also been used to probe the cognitive processes giving rise to the sense of acceptability itself, the central finding being that acceptability reflects processing ease. Exploring what this finding means will require not only further empirical work on the acceptability judgment process, but also theoretical work on the nature of grammar.

Child phonology refers to virtually every phonetic and phonological phenomenon observable in the speech productions of children, including babbles. This includes qualitative and quantitative aspects of babbled utterances as well as all behaviors such as the deletion or modification of the sounds and syllables contained in the adult (target) forms that the child is trying to reproduce in his or her spoken utterances. This research is also increasingly concerned with issues in speech perception, a field of investigation that has traditionally followed its own course; it is only recently that the two fields have started to converge. The recent history of research on child phonology, the theoretical approaches and debates surrounding it, as well as the research methods and resources that have been employed to address these issues empirically, parallel the evolution of phonology, phonetics, and psycholinguistics as general fields of investigation. Child phonology contributes important observations, often organized in terms of developmental time periods, which can extend from the child’s earliest babbles to the stage when he or she masters the sounds, sound combinations, and suprasegmental properties of the ambient (target) language. Central debates within the field of child phonology concern the nature and origins of phonological representations as well as the ways in which they are acquired by children. Since the mid-1900s, the most central approaches to these questions have tended to fall on each side of the general divide between generative vs. functionalist (usage-based) approaches to phonology. Traditionally, generative approaches have embraced a universal stance on phonological primitives and their organization within hierarchical phonological representations, assumed to be innately available as part of the human language faculty. In contrast to this, functionalist approaches have utilized flatter (non-hierarchical) representational models and rejected nativist claims about the origin of phonological constructs. Since the beginning of the 1990s, this divide has been blurred significantly, both through the elaboration of constraint-based frameworks that incorporate phonetic evidence, from both speech perception and production, as part of accounts of phonological patterning, and through the formulation of emergentist approaches to phonological representation. Within this context, while controversies remain concerning the nature of phonological representations, debates are fueled by new outlooks on factors that might affect their emergence, including the types of learning mechanisms involved, the nature of the evidence available to the learner (e.g., perceptual, articulatory, and distributional), as well as the extent to which the learner can abstract away from this evidence. In parallel, recent advances in computer-assisted research methods and data availability, especially within the context of the PhonBank project, offer researchers unprecedented support for large-scale investigations of child language corpora. This combination of theoretical and methodological advances provides new and fertile grounds for research on child phonology and related implications for phonological theory.

Computational phonology studies the nature of the computations necessary and sufficient for characterizing phonological knowledge. As a field it is informed by the theories of computation and phonology.

The computational nature of phonological knowledge is important because at a fundamental level it is about the psychological nature of memory as it pertains to phonological knowledge. Different types of phonological knowledge can be characterized as computational problems, and the solutions to these problems reveal their computational nature. In contrast to syntactic knowledge, there is clear evidence that phonological knowledge is computationally bounded to the so-called regular classes of sets and relations. These classes have multiple mathematical characterizations in terms of logic, automata, and algebra with significant implications for the nature of memory. In fact, there is evidence that phonological knowledge is bounded by particular subregular classes, with more restrictive logical, automata-theoretic, and algebraic characterizations, and thus by weaker models of memory.

Connectionism is an important theoretical framework for the study of human cognition and behavior. Also known as Parallel Distributed Processing (PDP) or Artificial Neural Networks (ANN), connectionism advocates that learning, representation, and processing of information in mind are parallel, distributed, and interactive in nature. It argues for the emergence of human cognition as the outcome of large networks of interactive processing units operating simultaneously. Inspired by findings from neural science and artificial intelligence, connectionism is a powerful computational tool, and it has had profound impact on many areas of research, including linguistics. Since the beginning of connectionism, many connectionist models have been developed to account for a wide range of important linguistic phenomena observed in monolingual research, such as speech perception, speech production, semantic representation, and early lexical development in children. Recently, the application of connectionism to bilingual research has also gathered momentum. Connectionist models are often precise in the specification of modeling parameters and flexible in the manipulation of relevant variables in the model to address relevant theoretical questions, therefore they can provide significant advantages in testing mechanisms underlying language processes.

Morphological defectiveness refers to situations where one or more paradigmatic forms of a lexeme are not realized, without plausible syntactic, semantic, or phonological causes. The phenomenon tends to be associated with low-frequency lexemes and loanwords. Typically, defectiveness is gradient, lexeme-specific, and sensitive to the internal structure of paradigms.

The existence of defectiveness is a challenge to acquisition models and morphological theories where there are elsewhere operations to materialize items. For this reason, defectiveness has become a rich field of research in recent years, with distinct approaches that view it as an item-specific idiosyncrasy, as an epiphenomenal result of rule competition, or as a normal morphological alternation within a paradigmatic space.

The theory of speech perception as direct derives from a general direct-realist account of perception. A realist stance on perception is that perceiving enables occupants of an ecological niche to know its component layouts, objects, animals, and events. “Direct” perception means that perceivers are in unmediated contact with their niche (mediated neither by internally generated representations of the environment nor by inferences made on the basis of fragmentary input to the perceptual systems). Direct perception is possible because energy arrays that have been causally structured by niche components and that are available to perceivers specify (i.e., stand in 1:1 relation to) components of the niche. Typically, perception is multi-modal; that is, perception of the environment depends on specifying information present in, or even spanning, multiple energy arrays.

Applied to speech perception, the theory begins with the observation that speech perception involves the same perceptual systems that, in a direct-realist theory, enable direct perception of the environment. Most notably, the auditory system supports speech perception, but also the visual system, and sometimes other perceptual systems. Perception of language forms (consonants, vowels, word forms) can be direct if the forms lawfully cause specifying patterning in the energy arrays available to perceivers. In Articulatory Phonology, the primitive language forms (constituting consonants and vowels) are linguistically significant gestures of the vocal tract, which cause patterning in air and on the face. Descriptions are provided of informational patterning in acoustic and other energy arrays. Evidence is next reviewed that speech perceivers make use of acoustic and cross modal information about the phonetic gestures constituting consonants and vowels to perceive the gestures.

Significant problems arise for the viability of a theory of direct perception of speech. One is the “inverse problem,” the difficulty of recovering vocal tract shapes or actions from acoustic input. Two other problems arise because speakers coarticulate when they speak. That is, they temporally overlap production of serially nearby consonants and vowels so that there are no discrete segments in the acoustic signal corresponding to the discrete consonants and vowels that talkers intend to convey (the “segmentation problem”), and there is massive context-sensitivity in acoustic (and optical and other modalities) patterning (the “invariance problem”). The present article suggests solutions to these problems.

The article also reviews signatures of a direct mode of speech perception, including that perceivers use cross-modal speech information when it is available and exhibit various indications of perception-production linkages, such as rapid imitation and a disposition to converge in dialect with interlocutors.

An underdeveloped domain within the theory concerns the very important role of longer- and shorter-term learning in speech perception. Infants develop language-specific modes of attention to acoustic speech signals (and optical information for speech), and adult listeners attune to novel dialects or foreign accents. Moreover, listeners make use of lexical knowledge and statistical properties of the language in speech perception. Some progress has been made in incorporating infant learning into a theory of direct perception of speech, but much less progress has been made in the other areas.

Iconicity is a relationship of resemblance or similarity between the two aspects of a sign: its form and its meaning. An iconic sign is one whose form resembles its meaning in some way. The opposite of iconicity is arbitrariness. In an arbitrary sign, the association between form and meaning is based solely on convention; there is nothing in the form of the sign that resembles aspects of its meaning. The Hindu-Arabic numerals 1, 2, 3 are arbitrary, because their current form does not correlate to any aspect of their meaning. In contrast, the Roman numerals I, II, III are iconic, because the number of occurrences of the sign I correlates with the quantity that the numerals represent. Because iconicity has to do with the properties of signs in general and not only those of linguistic signs, it plays an important role in the field of semiotics—the study of signs and signaling. However, language is the most pervasive symbolic communicative system used by humans, and the notion of iconicity plays an important role in characterizing the linguistic sign and linguistic systems. Iconicity is also central to the study of literary uses of language, such as prose and poetry.

There are various types of iconicity: the form of a sign may resemble aspects of its meaning in several ways: it may create a mental image of the concept (imagic iconicity), or its structure and the arrangement of its elements may resemble the structural relationship between components of the concept represented (diagrammatic iconicity). An example of the first type is the word cuckoo, whose sounds resemble the call of the bird, or a sign such as RABBIT in Israeli Sign Language, whose form—the hands representing the rabbit's long ears—resembles a visual property of that animal. An example of diagrammatic iconicity is vēnī, vīdī, vīcī, where the order of clauses in a discourse is understood as reflecting the sequence of events in the world.

Iconicity is found on all linguistic levels: phonology, morphology, syntax, semantics, and discourse. It is found both in spoken languages and in sign languages. However, sign languages, because of the visual-gestural modality through which they are transmitted, are much richer in iconic devices, and therefore offer a rich array of topics and perspectives for investigating iconicity, and the interaction between iconicity and language structure.

The study of second language phonetics is concerned with three broad and overlapping research areas: the characteristics of second language speech production and perception, the consequences of perceiving and producing nonnative speech sounds with a foreign accent, and the causes and factors that shape second language phonetics. Second language learners and bilinguals typically produce and perceive the sounds of a nonnative language in ways that are different from native speakers. These deviations from native norms can be attributed largely, but not exclusively, to the phonetic system of the native language. Non-nativelike speech perception and production may have both social consequences (e.g., stereotyping) and linguistic–communicative consequences (e.g., reduced intelligibility). Research on second language phonetics over the past ca. 30 years has resulted in a fairly good understanding of causes of nonnative speech production and perception, and these insights have to a large extent been driven by tests of the predictions of models of second language speech learning and of cross-language speech perception. It is generally accepted that the characteristics of second language speech are predominantly due to how second language learners map the sounds of the nonnative to the native language. This mapping cannot be entirely predicted from theoretical or acoustic comparisons of the sound systems of the languages involved, but has to be determined empirically through tests of perceptual assimilation. The most influential learner factors which shape how a second language is perceived and produced are the age of learning and the amount and quality of exposure to the second language. A very important and far-reaching finding from research on second language phonetics is that age effects are not due to neurological maturation which could result in the attrition of phonetic learning ability, but to the way phonetic categories develop as a function of experience with surrounding sound systems.

In their conversational interactions with speakers, listeners aim to understand what a speaker is saying, that is, they aim to arrive at the linguistic message, which is interwoven with social and other information, being conveyed by the input speech signal. Across the more than 60 years of speech perception research, a foundational issue has been to account for listeners’ ability to achieve stable linguistic percepts corresponding to the speaker’s intended message despite highly variable acoustic signals. Research has especially focused on acoustic variants attributable to the phonetic context in which a given phonological form occurs and on variants attributable to the particular speaker who produced the signal. These context- and speaker-dependent variants reveal the complex—albeit informationally rich—patterns that bombard listeners in their everyday interactions.

How do listeners deal with these variable acoustic patterns? Empirical studies that address this question provide clear evidence that perception is a malleable, dynamic, and active process. Findings show that listeners perceptually factor out, or compensate for, the variation due to context yet also use that same variation in deciding what a speaker has said. Similarly, listeners adjust, or normalize, for the variation introduced by speakers who differ in their anatomical and socio-indexical characteristics, yet listeners also use that socially structured variation to facilitate their linguistic judgments. Investigations of the time course of perception show that these perceptual accommodations occur rapidly, as the acoustic signal unfolds in real time. Thus, listeners closely attend to the phonetic details made available by different contexts and different speakers. The structured, lawful nature of this variation informs perception.

Speech perception changes over time not only in listeners’ moment-by-moment processing, but also across the life span of individuals as they acquire their native language(s), non-native languages, and new dialects and as they encounter other novel speech experiences. These listener-specific experiences contribute to individual differences in perceptual processing. However, even listeners from linguistically homogenous backgrounds differ in their attention to the various acoustic properties that simultaneously convey linguistically and socially meaningful information. The nature and source of listener-specific perceptual strategies serve as an important window on perceptual processing and on how that processing might contribute to sound change.

Theories of speech perception aim to explain how listeners interpret the input acoustic signal as linguistic forms. A theoretical account should specify the principles that underlie accurate, stable, flexible, and dynamic perception as achieved by different listeners in different contexts. Current theories differ in their conception of the nature of the information that listeners recover from the acoustic signal, with one fundamental distinction being whether the recovered information is gestural or auditory. Current approaches also differ in their conception of the nature of phonological representations in relation to speech perception, although there is increasing consensus that these representations are more detailed than the abstract, invariant representations of traditional formal phonology. Ongoing work in this area investigates how both abstract information and detailed acoustic information are stored and retrieved, and how best to integrate these types of information in a single theoretical model.