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

Lexical Stress

Used to distinguish nouns from verbs

Ex: Record (noun) vs Record (verb)

Sentence or phrase stress

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

Highlights important information

Acoustic Determinants of Stress

1. Higher Pitch (F0)

2. Higher Duration

3. Greater Intensity/Loudness

Characteristics of stress syllables

• Higher fundamental frequency

• Longer duration

• Greater intensity (Higher subglottal pressure)

Intonation

Changes in pitch across phrases and sentences

Conveys emotion, question vs statement, completeness

Rise-fall intonation

Natural breath pattern

Final rise

Question or incompleteness

Declination

Pitch drop at the end of a phrase

Controlled by:

• Raising pitch (F0): Cricothyroid muscle tension

• Lowering pitch (F0): Muscle relaxation and reduced subglottal pressure

Duration

Varies over many units in speech

Influenced by:

• Intrinsic properties/sound type (diphthongs longer than lax vowels)

• Context (vowel longer before voiced consonants)

• Phrase final lengthening (Sound at end of phrases are longer)

Juncture

Refers to how sounds are connected or separated

Syllable affiliation changes meaning

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

English vs Spanish Stress

English: Stress timed (Morse code rhythm)

Spanish: syllable timed (Even rhythm)