Acoustics of Prosody

Prosody

Study of the tune and rhythm of speech and how these features contribute meaning

Characterized by:

• Vocal Pitch (Fundamental Frequency)

• Loudness (Acoustic Intensity)

• Rhythm (Phoneme and Syllable Duration)

Suprasegmental

Features above the level of the phoneme

Nature of this type of feature:

• Usually cover more than one segment of connected speech

• Some relate directly to entire syllables

• Some relate to entire phrases or sentences

• Some relate to how sequences of sounds are joined to or separated from one another

Stress

Applies to the syllable

Used to distinguish nouns from verbs

Used to distinguish compound nouns from sequences of adjectives + nouns

Functions as a “pointer” by indicating which information in an utterance is most important

Sentence or phrase stress

Degree of emphasis on individual syllables and words within sentences and phrases

Degree of stress indicates the relative importance of the various bits of information the speaker intends to convey

Acoustic Determinants of Stress

1. Fundamental Frequency/Pitch

2. Duration

3. Intensity/Loudness

Characteristics of stress syllables

• Higher fundamental frequency

• Longer duration

• Greater intensity (Higher subglottal pressure)

Intonation

Applies to phrases and sentences

Conveys emotion, question vs statement, completeness

Rise-fall intonation

Natural breath group

Final rise

Question or incompleteness

Declination

Pitch drop at the end of a phrase

Duration

Varies over many units in speech

Influenced by:

• Sound type (diphthongs longer than lax vowels)

• Context (vowel longer before voiced consonants)

• Phrase final lengthening

Juncture

Describes whether adjacent phonemes are closely associated or not (depends on syllable boundaries)

How sounds connect or separate in speech

Ex: A name or an aim

Speech in context

Speech is continuous, not isolated “beads on a string”

Phonemes interact via assimilation and coarticulation

Syllables are key units consisting of onset, nucleus, and coda

Lexical Stress

Affects syllables in words

Ex: Object vs Object

English vs Spanish Stress

English: Stress timed (Morse code rhythm)

Spanish: syllable timed (Even rhythm)