The Penta Model of Speech Melody: Transmitting Multiple Communicative Functions in Parallel

Existing models of intonation typically define intonational components primarily in form and only secondarily in function. They also typically try to link observed F0 contours directly to intonational meanings. The PENTA model of speech melody presented in this paper deviates from this tradition. First, it makes a clear separation between the meaning-bearing components of intonation, which are functionally defined, and the primitives of speech melody, which are defined purely in form (i.e., devoid of meaning) and readily implementable in articulation. Second, it specifies mechanisms for concurrent transmission of multiple intonational functions. Third, it specifies a continuous link between articulatory mechanisms of F0 contour generation and the functional components of speech melody. INTRODUCTION An important goal in studying intonation is to identify its components and understand how they function in speech. Much of the research toward this goal is done by observing various aspects of the acoustic signals, including the fundamental frequency (F0), amplitude, duration, voice quality, and spectral characteristics. Of these by far the most researched is F0, which is the most direct correlate of speech melody. To identify tonal and intonational components from F0, much effort has been devoted to figuring out how observed F0 curves should be divided into individual intonational components. Various proposals have been made, as seen in a variety of intonation models. Despite extensive differences among them, however, most of the existing models of intonation share two critical assumptions. First, intonational components are defined primarily in form and only secondarily in function. Second, the form-defined intonational components are directly linked to meaning. These assumptions are behind proposed intonational components such as nucleus, head and tail in the British model (Cruttenden, 1997), H and L tones (manifesting as F0 peaks and valleys) in the Autosegmental-Metrical (AM) model (Ladd, 1996; Pierrehumbert, 1980), accent and phrase commands in the command-response model (Fujisaki, 1988), and complex F0 shapes that are either fully overt or stylized in the Bolinger model (Bolinger, 1989), the IPO model ('t Hart et al., 1990) or the tilt model (Taylor, 2000). Both of these assumptions, however, need to be reconsidered if we were to develop an effective comprehensive model of intonation. First, intonational components should be defined in terms of function rather than form. As pointed out recently by Studdert-Kennedy (in press) about language evolution: “...what we need...is a model of language function. Form follows function, not function form”. This should be true for our understanding of various synchronic aspects of speech as well. That is, it is unlikely that communicative functions have evolved to serve preexisting linguistic forms. Rather, it is more likely that linguistic forms have evolved to serve various communicative functions, i.e., to convey different communicative meanings.