NEUROBIOLOGY OF LANGUAGE Edited by GREGORY HICKOK Department of Cognitive Sciences, University of California, Irvine, CA, USA STEVEN L. SMALL Department of Neurology, University of California, Irvine, CA, USA AMSTERDAM • BOSTON • HEIDELBERG • LONDON NEW YORK • OXFORD • PARIS • SAN DIEGO SAN FRANCISCO • SINGAPORE • SYDNEY • TOKYO Academic Press is an imprint of Elsevier SECTION C BEHAVIORAL FOUNDATIONS This page intentionally left blank CHAPTER 12 Phonology William J. Idsardi1,2 and Philip J. Monahan3,4 1Department of Linguistics, University of Maryland, College Park, MD, USA; 2Neuroscience and Cognitive Science Program, University of Maryland, College Park, MD, USA; 3Centre for French and Linguistics, University of Toronto Scarborough, Toronto, ON, Canada; 4Department of Linguistics, University of Toronto, Toronto, ON, Canada 12.1 INTRODUCTION have very specific knowledge about a word’s form from a single presentation and can recognize and Phonology is typically defined as “the study of repeat such word-forms without much effort, all speech sounds of a language or languages, and the without knowing its meaning. Phonology studies the laws governing them,”1 particularly the laws govern- regularities of form (i.e., “rules without meaning”) ing the composition and combination of speech (Staal, 1990) and the laws of combination for speech sounds in language. This definition reflects a seg- sounds and their sub-parts. mental bias in the historical development of the field Any account needs to address the fact that and we can offer a more general definition: the study speech is produced by one anatomical system (the of the knowledge and representations of the sound mouth) and perceived with another (the auditory system of human languages. From a neurobiological system). Our ability to repeat new word-forms, or cognitive neuroscience perspective, one can such as “glark,” is evidence that people effortlessly consider phonology as the study of the mental model map between these two systems. Moreover, new for human speech. In this brief review, we restrict word-forms can be stored in both short-term and ourselves to spoken language, although analogous long-term memory. As a result, phonology must concerns hold for signed language (Brentari, 2011). confront the conversion of representations (i.e., data Moreover, we limit the discussion to what we con- structures) between three broad neural systems: mem- sider the most important aspects of phonology. ory, action, and perception (the MAP loop; Poeppel & These include: (i) the mappings between three sys- Idsardi, 2011). Each system has further sub-systems tems of representation: action, perception, and long- that we ignore here. The basic proposal is that this term memory; (ii) the fundamental components of is done through the use of phonological primitives speech sounds (i.e., distinctive features); (iii) the laws (features), which are temporally organized (chunked, of combinations of speech sounds, both adjacent and grouped, coordinated) on at least two fundamental long-distance; and (iv) the chunking of speech sounds time scales: the feature or segment and the syllable into larger units, especially syllables. (Poeppel, 2003). To begin, consider the word-form “glark.” Given this string of letters, native speakers of English will have an idea of how to pronounce it and what it 12.2 SPEECH SOUNDS would sound like if another person said it. They would AND THE MAP LOOP have little idea, if any, of what it means.2 The meaning of a word is arbitrary given its form, and it could The alphabet is an incredible human invention, but mean something else entirely. Consequently, we can its ubiquity overly influences our ideas regarding the 1Longman Dictionary of Contemporary English. 2Urban Dictionary (http://www.urbandictionary.com/) states that it means “to slowly grasp the meaning of a word or concept, based on the situation in which it is used” (i.e., almost grokking a concept). Neurobiology of Language. DOI: http://dx.doi.org/10.1016/B978-0-12-407794-2.00012-2 141 © 2016 Elsevier Inc. All rights reserved. 142 12. PHONOLOGY basic units of speech. This continues to this day and is Each of these structures has some degrees of free- evident in the influence of the International Phonetic dom of movement, which we describe in terms of Alphabet (IPA; http://www.langsci.ucl.ac.uk/ipa/) their deflection from a neutral posture for speaking. for transcribing speech. Not all writing systems are The position for the mid-central vowel schwa, [ə], is alphabetic, however. Some languages choose ortho- considered to be the neutral posture of the speech graphic units larger than single sounds (moras, sylla- articulators. In most structures, two opposite directions bles) and a few, such as Bell’s Visible Speech (Bell, of movement are possible, yielding three stable regions 1867) and the Korean orthographic system Hangul of articulation, that is, the tongue dorsum can be put (Kim-Renaud, 1997), decompose sounds into their into a high, mid (neutral), or low position. In the neu- component articulations, all of which constitute impor- tral posture the velum is closed, but it can be opened tant, interconnected representations for speech. to allow air to flow through the nose, and such speech sounds are classified as nasal (as in English “m” [m]). 12.2.1 Action or Articulation of Speech The lips can deflect from the neutral posture by being rounded (as in English “oo” [u]) or drawn back (as in The musculature of the mouth has historically been English “ee” [i]). The tongue tip can be curled conca- somewhat more accessible to investigation than audi- vely or convexly either along its length (yielding retro- tion or memory, and linguistic phonetics has often dis- flex and laminal sounds, respectively) or across its played a bias toward classifying speech sounds in terms width (yielding grooved and lateral sounds, respec- of the actions needed to produce them (i.e., the articula- tively). The tongue dorsum (as mentioned) can be tion of the speech sounds by the mouth). For example, moved vertically (high or low) and horizontally (front the standard IPA charts for consonants and vowels or back), and the tongue root can be moved horizon- (Figure 12.1) are organized by how speech sounds are tally (advanced or retracted). articulated. The columns in Figure 12.1A arrange conso- The larynx (Figure 12.3) is particularly complex and nants with respect to where they are articulated in the can be moved along three different dimensions: modi- mouth (note: right to left corresponds to anterior to fying its vertical position (raised or lowered), modify- posterior position within the oral cavity), and the rows ing its tilt (rotated forward to slacken the vocal folds correspond to how they are articulated (i.e., their or rotated backwards to stiffen them), and changing manner of articulation). The horizontal dimension in the degree of separation of the vocal folds (adducted Figure 12.1B represents the relative frontness-backness or abducted). Furthermore, the lips and the tongue of the tongue, and the vertical dimension represents the blade and dorsum can close off the mouth to dif- aperture of the mouth during production. These are the ferent degrees (termed the “manner” of production): standard methods for organizing consonant and vowel completely closed (stops), nearly closed with turbulent inventories in languages. airflow (fricatives), or substantially open (approxi- Within the oral cavity, there are several controllable mants). Taken together, these articulatory maneuvers structures used to produce speech sounds. These include describe how to make various speech sounds. For the larynx, the velum, the tongue (which is further example, an English [s], as in “sea”, is an abducted divided into three relatively independently moveable (voiceless, high glottal airflow) grooved fricative. sections: the tongue blade, the tongue dorsum, and the Furthermore, as described in Section 12.3, the antago- tongue root), and the lips (see Figure 12.2 reproduced nistic relationships between articulator movements from Bell, 1867; for more detail see Zemlin, 1998). serve as the basis for the featural distinctions (whether (A) (B) Place of articulation Front Central Back Labio- Alveo- Bilabial Interdental Alveolar Palatal Velar Glottal dental palatal Close Stop Fricative Close-mid Affricate Nasal Lateral Open-mid Manner of articulation Retroflex Glide Open FIGURE 12.1 IPA charts for American English (A) consonants and (B) vowels. C. BEHAVIORAL FOUNDATIONS 12.2 SPEECH SOUNDS AND THE MAP LOOP 143 monovalent, equipollent, or binary; see Fant, 1973; 12.2.2 Perception or Audition of Speech Trubetzkoy, 1969) that have proven so powerful in understanding not only the composition of speech A great deal of the literature regarding speech per- sounds but also the phonology of human language. ception deals with how “special” speech is (Liberman, 1996) or is not. Often, this is cast as a debate between the motor theory of speech perception (Liberman & Mattingly, 1985) and speech as an area of expertise 4 within general auditory perception (Carbonnell & Lotto, 2014). The motor theory of speech perception 7 3 6 posits speech-specific mechanisms that recover the 5 7 intended articulatory gestures that produced the phys- 2 8 ical auditory stimulus. General auditory perception models, however, posit that the primary representa- tional modality of speech perception is auditory and the mechanisms used during speech perception are 1 the same as those responsible for nonspeech auditory perception. This dichotomy, in some ways, parallels debates about face perception (Rhodes, Calder, Johnson, & Haxby, 2011). Since the development of the 1. The larynx 5. The back of the tongue sound spectrograph (Potter, Kopp, & Green, 1947)and 2. The pharynx 6. The front of the tongue the Haskins pattern playback machine (Cooper, 3. The soft palate 7. The point of the tongue Liberman, & Borst, 1951), it has been known that it is 4. The action of the soft palate in 8. The lips closing the nasal passage technologically feasible to analyze and accurately reproduce speech with timeÀfrequencyÀamplitude FIGURE 12.2 Speech articulators.