The present study investigated the production of lexical stress by native speakers of English (NE), Arabic learners of English (ALE), and native speakers of Arabic (NA). In the first experiment, minimal pairs (e.g., ‘con.flict, con.’flict) were recorded by 8 native speakers of English and 16 (8 advanced and 8 beginning) learners. For comparison, a second experiment examined acoustic cues used to indicate stress in 8 native Arabic speakers. In both experiments, four acoustic cues were examined: duration, fundamental frequency, amplitude, and second formant frequency. Results showed that NE consistently used all four cues to signal stress, with longer duration, higher fundamental frequency, higher amplitude, and less reduced vowel quality for stressed syllables. Advanced ALE, but not the beginning ALE, made distinctions in duration and amplitude similar to the duration and amplitude cues used by NE. For fundamental frequency, both advanced and beginning ALE produced even higher fundamental frequency values for stressed syllables than NE and both learner groups produced full (unreduced) vowels in stressed and unstressed syllables. Implications for acoustic cues to lexical stress in English as a second language are discussed.

Introduction

Mandarin tones are manifested physically by different fundamental frequency (F0) values with F0 height and F0 contour as the primary acoustic parameters (Liu, 1924; Howie, 1976; Wu, 1986). In addition, amplitude and temporal properties such as overall duration and Turning Point are also effective phonetic correlates of the tones (Lin, 1965; Chuang et al., 1971; Moore & Jongman, 1997). Studies in the perceptual domain have shown that various acoustic cues are functionally integrated when Mandarin speakers identify the tones (Gandour, 1984; Massaro, Cohen & Tseng, 1985; Gårding et al., 1986; Blicher, Diehl & Cohen, 1990; Shen & Lin, 1991; Moore & Jongman, 1997). The hemispheric processing of Mandarin tones for native speakers is lateralized in the left hemisphere, suggesting that tones are processed as linguistic units, just like segmental properties (Hsieh et al., 2001; Wang, Jongman & Sereno, 2001).

These results about the processing of Mandarin tones for native speakers raise the question as to whether non-native speakers process tones auditorily (i.e. based on innate psychoacoustic mechanisms) or linguistically (i.e. resulting from language-specific experience). Indeed, for speakers whose native language is nontonal, tone has presented great difficulty, since the functional association between the F0 characteristics and the segmental structure is unfamiliar to them (e.g. Kiriloff, 1969; Bluhme & Burr, 1971; Shen, 1989). A number of crosslinguistic studies have been conducted to examine if and how nontonal speakers process the tones differently, how they improve the processing of the tones as a result of learning, and how this learning is instantiated in the brain.

Introduction

Lexical tones are pitch patterns that serve to provide contrasts in word meaning. They perform this function analogously to segments such as voiced and voiceless stops, except that tone may extend beyond one segment. Mandarin Chinese phonemically distinguishes four tones, with tone 1 having high-level pitch, tone 2 high-rising pitch, tone 3 low-dipping pitch, and tone 4 high-falling pitch (Chao, 1948). The same segmental context carries different meanings depending on the tone. For example, the meaning of Mandarin Chinese ma with tone 1 is “mother,” the tone 2 version means “hemp,” and the tones 3 and 4 meanings are “horse” and “scold,” respectively.

Pitch or tone is a function of the rate of vocal fold vibration (see Ohala, 1978, for a review of tone production). As stipulated in the myoelastic–aerodynamic theory of vocal fold vibration (e.g. Van den Berg, 1958), it is a cyclic process that is achieved by a complex combination of aerostatic and aerodynamic forces, operating together with air flow and laryngeal muscle forces. Changes in fundamental frequency (or in rate of vocal fold vibration) are made by manipulating tension in the vocal folds. This tension is increased or decreased by the laryngeal muscles, particularly the cricothyroid muscle and the thyroarytenoids. The cricothyroid has been linked to both rises and falls in pitch, while sternohyoid activity is associated with pitch lowering (Sagart et al., 1986).

The rate of vocal fold vibration is quantified as the fundamental frequency (F0), expressed in Hertz (Hz).

Introduction

Although the search for linguistic universals has been successful in discovering a wide variety of similarities among the languages of the world (Greenberg 1966, 1978), few generalities about the semantic properties of languages have been uncovered (Weinreich 1963). Some of the most striking examples of a structured semantic domain are to be found in the connection between sound and meaning. In principle, resemblances between meaning and sound should not exist. As Greenberg (1957) notes, the connection between sound and meaning is essentially arbitrary. A meaning can theoretically be represented by almost any set of sounds in a language.

Despite claims that this principle applies to all languages, the articles in this volume show that connections between the meanings and the sounds of language do exist. Two universal and well-documented cases of sound symbolism are relevant to the present study. First, Ultan (1978) found evidence for distance symbolism. The notion of distance symbolism must be considered within the broader framework of deixis. Deixis refers to those features of the language which reflect the spatio-temporal coordinates of the relative situation of the utterance. Distinctions are made between things that are near in space and/or time versus things that are far in space and/or time. In an analysis of 136 languages, Ultan found that 33.1% of the sample exhibited distance (spatial) symbolism in their demonstrative system. More importantly, the languages that overtly symbolized distance relationships predominantly used front or high front vowels to represent proximity to the speaker. Ultan also found universal correspondences for size symbolism in language. Some languages overtly mark words expressing diminution by changing the phonological features of the sound in the root.