1. Terminology

The IPA provides a group of symbols for stress, length, intonation, syllabification and tone under the general heading “suprasegmentals”, reflecting a conceptual division of speech into “segmental” and “suprasegmental” parts. However, as we shall see, this division is not very clean, with phonetic correlates of stress, intonation etc. often manifest in the consonants and vowels, i.e. at the segmental level. Therefore, rather than referring to “segmentals vs. suprasegmentals”, I prefer the more general term “prosody” for these phenomena (among others).

2. Stress and its phonetic correlates

In English, the term “stress” is used in reference to the degree of prominence of individual syllables of single words (lexical stress), e.g. elephant (stressed - unstressed - unstressed) vs. elephantine (unstressed? - unstressed - stressed - unstressed). But not every word is actually stressed when it occurs in a sentence: some lexical stresses are picked out for sentential stress - perhaps better called “accent”. E.g. “Albert went to the zoo.”

IPA symbols for primary stress [ˈ] and secondary stress [ˌ] may be placed before vowels, or equally well at the beginning of each syllable (thus also providing some information about syllable boundaries):
elephant [ˈelɪfənt], elephantine [ˌelɪfˈanˌtɑɪn].

Ladefoged (1993: 249), like many introductory phonetics textbooks, says “the nature of stress is fairly well understood. Stressed sounds are those on which the speaker expends more muscular energy ... so that there is an additional increase in pitch.” Davenport and Hannahs (p. 23), similarly, write “Stressed syllables are produced with more muscular effort, and are louder or longer than unstressed syllables.” There are some problems with this view:

a) In some languages (e.g. Welsh, see Williams 1982; Chamorro, see Chung 1983) and even in some dialects of English (e.g. Birmingham, Tyneside, Welsh English) the pitch is lower on stressed syllables than unstressed syllables, and stressed syllables may be shorter and quieter than unstressed syllables.

b) There are other phonetic correlates of stress too. Cf. English:

In these examples, the stressed syllables have longer, closer, more rounded vowels and initial [h], whereas unstressed syllables have shorter, more central, less rounded vowels and somtimes initial [h] is absent. The phonetics of stress, then, includes not just loudness, pitch and duration, but also vowel quality, liprounding. Vowel quality differences are especially important markers of stress in English. Unstressed vowels are often said to be “reduced” to [ə] or [ɪ]. Some English vowels, e.g. [ɒ], are only found in syllables with  (primary or secondary) stress: tonic [ˈtɒnɪk] vs. [təˈnɪsɪtɪ]. The aspiration of voiceless aspirated stops is stronger in stressed syllables than unstressed syllables: e.g. [ˈp^hhet^hrəl] vs. [p^həˈt^hhroʊl]

c) The phonetic realization of stress is rather language-specific. Trubetzkoy (1939) pointed out that in (West) Bulgarian the contrast between close /u/ and mid /ɔ/ found in stressed syllables is neutralized in unstressed syllables, where only /u/ - the closer phoneme - occurs. (It is actually pronounced [o] in unstressed syllables.) In contrast, in Russian, the contrast between open /a/ and mid /o/ is neutralized in unstressed syllables, where /o/ is unrounded and lowered to /a/.

Similarly, in Chamorro, mid vowel (allophones) are found in stressed closed syllables and only close vowel (allophones) occur in unstressed syllables, e.g. [ˈsoŋsuŋ] “village” vs. [i suŋˈsoŋɲa] “his village”; [ˈtsoʔtsuʔ] “word” vs. [i tsoʔˈtsoʔmu] “your (sg.) work”; [ˈɡwesɡwis] “to brush”, [ˈsensin] “flesh”, [ˈneni] “baby”, etc. This is the opposite of the correlation between stress and vowel height in the English examples above, in which stressed [ˈu] is close and unstressed [ə] is mid. It appears then as if stress is not a well-defined phonetic feature, but an abstract phonological feature whose phonetic realization is i) manifold and ii) language-specific.

3. Duration

Length contrasts can be transcribed by doubling of letters (for simple long vs. short duration), or using length marks: [ː] (in print, or, just as good, [:]), [ˑ] (or [·]). E.g. Luganda [k̩̀kúlà] “treasure” vs. [kúlà] “grow up”, Italian nonno [ˈnonnɔ] “grandfather” vs. nono [ˈnonɔ] “ninth”, or even English [kkju] “thank you/f*ck you” (depending on intonation and context of use) vs. [kju] “cue/queue”. There is also a diacritic for “extra short” sounds, e.g. [ă].

Avoid confusing phonetic duration (measured e.g. in milliseconds) with phonological length (e.g. long vs. short vowels and consonants). Many durational differences in English are purely allophonic. Note that the duration of the short vowel /a/ can easily exceed that of the long vowel /iː/ because more open vowels have a longer duration in English than closer vowels.

4. Prosody reconsidered

The preceding paragraphs have shown that many more features than duration and pitch are (or can be) prosodic. What, then, do we mean by “prosody”?

a) Features (or groups of features) not located at a single place in the sequence of consonants and vowels (e.g. stress, tone).

b) For example, (groups of) features associated with a whole syllable, word or phrase.

c) For example, features of the boundaries of syllables and words (e.g. assimilation, linking, absence vs. presence of initial [h] in the ʻto him/herʼ examples above). “Grenzsignale”.

5. What else can be a prosody?

Virtually anything! Some examples:

a) Place of articulation (e.g. place assimilation at word-junctures, or coronal consonant harmony in Chumash).

b) Manner of articulation (e.g. initial consonant mutation, as in Welsh), including ...

c) Degree of stricture (e.g. spirantization of final stops as a boundary feature)

d) Voicing (cf. voicing assimilation at word-junctures and in initial mutation)

e) Retroflexion (e.g. Sanskrit ruki and nati rules)

f) Frontness and backness (e.g. umlaut, vowel harmony)

g) Openness and closeness (e.g. vowel harmony)

h) Centrality and peripherality (cf. English stress above).

i) Aspiration, whisper (cf. stress above, Sanskrit Grassman's Law). In English [h] may only occur once in a word; apparent exceptions like jojoba are loan-words. Cf. “rough breathing” in Classical Greek.

j) Nasality e.g. in Terena, Sundanese, and in the Urhobo examples in previous handouts.

k) Glottality (e.g. [ʔ] in vowel-initial words in English or German, where it marks the beginning of a word or syllable; Danish stød: glottalization which is in many instances cognate with pitch accents in other Scandinavian languages).

l) Lip-rounding (vowel harmony; cf. also discussion of stress above).
 

References

Chung, S. (1983) Transderivational relationships in Chamorro phonology. Language 59 (1). 35-66.

Ladefoged, P. (1993) A Course in Phonetics. (Third Edition) Harcourt Brace Jovanovich.

Trubetzkoy, N. S. (1939) Grundzüge der Phonologie. Travaux du cercle linguistique de Prague 7.

Williams, B. (1982) The Problem of Stress in Welsh. Cambridge Papers in Phonetics and Experimental Linguistics Vol. 1. Department of Linguistics, University of Cambridge.