Stress: Phonotactic and Phonetic Evidence

Stress can be signaled through a number of different acoustic properties, including increased duration, greater intensity, and higher fundamental frequency. Stress may also affect segmental and syllable structure. Typically, stressed syllables trigger qualitative fortition and/or lengthening, whereas unstressed syllables are associated with lenition and/or shortening. To take an example of a stress-driven fortition process affecting syllable structure, Dutch (Booij 1995) inserts an intervocalic glottal stop as an onset to stressed vowels; epenthesis does not interrupt vowel sequences in which the second vowel is unstressed. We thus have pairs such as "xa.Os ‘chaos’ and a."/Or.ta ‘aorta’, in which the presence of glottal stop is predictable from stress. Chickasaw provides an example of durational fortition triggered by stress. American English provides well-described cases of lenition in unstressed syllables. For example, postvocalic coronal stops weaken to taps before unstressed syllabic sounds, e.g. /sIti/ → ["sI|i] ‘city’. Furthermore, most unstressed vowels reduce to schwa, e.g. ["kanÆtEkst] ‘context’ vs. [k ́n"tEkstu ́l] ‘contextual’, or may delete in certain contexts delete, e.g. ["tmeItoU] ~ ["t ́meItoU] ‘tomato’, ["ksœnd® ́] ~ [k ́"sœnd® ́] ‘Cassandra’. While most segmental effects of metrical structure can be transparently linked to stress, there are others that are not predictable from stress despite displaying properties typically associated with stress-induced alternations. For example, Nganasan (Tereshchenko 1979, Helimski 1998, Vaysman 2009) has an alternation between strong and weak intervocalic consonants, termed “consonant gradation”, whereby strong consonants, generally voiceless or prenasalized obstruents, alternate with weak consonants, typically voiced or not prenasalized. The appearance of strong and weak consonants is predictable from syllable count (1). In the onset of even-numbered non-initial syllables, the strong grade appears, while the weak grade appears in the onset of odd-numbered syllables. Long vowels interrupt the alternating syllable count and, as long as they are not word-initial, are always preceded by weak consonants.