4.1 Articulatory and Acoustic Phonetics

Articulatory and acoustic phonetics dive into how we make speech sounds and their physical properties. It's like understanding the mechanics of a car to appreciate how it runs smoothly.

This topic breaks down the vocal tract's parts and their roles in speech. We'll explore how different sounds are made and classified, and how to analyze speech using cool tech like spectrograms. It's the nuts and bolts of how we talk!

Anatomy and physiology of speech

Vocal tract components and functions

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• Human vocal tract comprises larynx, pharynx, oral cavity, and nasal cavity working together to produce speech sounds
• Larynx contains vocal folds serving as primary sound generation source in speech production
• Pharynx functions as resonating chamber modifying sound produced by larynx
• Oral cavity includes tongue, teeth, and lips crucial for articulation and shaping of speech sounds
• Velum (soft palate) controls air passage through nasal cavity distinguishing nasal from oral sounds
• Airflow from lungs provides energy source for speech production with diaphragm controlling breath support
• Articulators categorized as active (mobile) or passive (stationary) in their roles during speech production
  • Active articulators include tongue, lips, and soft palate
  • Passive articulators include teeth, hard palate, and alveolar ridge

Speech production process

• Initiation phase involves airflow generation from lungs
  • Diaphragm contracts to increase lung volume and create airflow
  • Intercostal muscles assist in controlling air pressure
• Phonation occurs at the larynx level
  • Vocal folds vibrate for voiced sounds (vowels, voiced consonants)
  • Vocal folds remain open for voiceless sounds
• Articulation shapes the sound in the vocal tract
  • Tongue movements create different vowel qualities
  • Lips, teeth, and tongue form various consonant sounds
• Resonance enhances and modifies the speech sound
  • Oral cavity acts as primary resonator for most speech sounds
  • Nasal cavity provides additional resonance for nasal sounds (m, n, ŋ)

Speech sound classification

Consonant classification

• Consonants categorized by three main features place of articulation, manner of articulation, and voicing
• Places of articulation include
  • Bilabial (both lips, p, b, m)
  • Labiodental (lower lip and upper teeth, f, v)
  • Dental (tongue tip and teeth, θ, ð)
  • Alveolar (tongue tip and alveolar ridge, t, d, s, z)
  • Postalveolar (tongue blade and back of alveolar ridge, ʃ, ʒ)
  • Palatal (tongue body and hard palate, j)
  • Velar (tongue back and soft palate, k, g, ŋ)
  • Glottal (vocal folds, h, ʔ)
• Manners of articulation encompass
  • Stops (complete closure, p, b, t, d, k, g)
  • Fricatives (narrow constriction, f, v, s, z, ʃ, ʒ)
  • Affricates (stop followed by fricative release, tʃ, dʒ)
  • Nasals (lowered velum, m, n, ŋ)
  • Liquids (partial obstruction, l, r)
  • Glides (quick movement to vowel, w, j)
• Voicing distinguishes between voiced (vocal fold vibration) and voiceless consonants

Vowel classification

• Vowels classified based on tongue height, tongue advancement, and lip rounding
• Tongue height categories include high, mid, and low vowels
  • High vowels (i, u)
  • Mid vowels (e, o)
  • Low vowels (a, ɑ)
• Tongue advancement describes front, central, and back vowels
  • Front vowels (i, e)
  • Central vowels (ə)
  • Back vowels (u, o)
• Lip rounding adds another dimension to vowel classification
  • Rounded vowels (u, o)
  • Unrounded vowels (i, e)
• Vowel quadrilateral represents articulatory space for vowel production
  • Vertical axis shows tongue height
  • Horizontal axis indicates tongue advancement
• Diphthongs involve movement from one vowel position to another (aɪ, aʊ, ɔɪ)

Acoustic properties of speech sounds

• Fundamental frequency (F0) relates to perceived pitch of voice
  • Determined by rate of vocal fold vibration
  • Typically higher in females and children compared to adult males
• Formant frequencies characterize vowel and some consonant sounds
  • First formant (F1) inversely related to tongue height
  • Second formant (F2) related to tongue advancement
• Voice onset time (VOT) crucial for distinguishing voiced and voiceless stops
  • Positive VOT for aspirated stops (p^h, t^h, k^h)
  • Negative or short lag VOT for voiced stops (b, d, g)
• Spectral characteristics provide information about manner of articulation
  • Fricatives show high-frequency noise
  • Stops exhibit silence followed by burst
• Distinctive features theory describes speech sounds based on binary acoustic-articulatory features
  • Features include [±voice], [±nasal], [±continuant], [±strident]

Acoustic analysis of speech

Waveform analysis

• Acoustic waveforms represent amplitude of sound over time
• Periodicity visible in waveforms for voiced sounds
  • Regular, repeating pattern indicates vocal fold vibration
• Aperiodicity characterizes voiceless sounds
  • Irregular patterns or noise-like appearance
• Amplitude envelope provides information about sound intensity
  • Higher amplitude corresponds to louder sounds
• Waveform shape offers clues about sound type
  • Abrupt changes indicate stop consonants
  • Continuous patterns suggest vowels or fricatives

Spectrogram interpretation

• Spectrograms display frequency content of speech sounds over time
• Darker areas on spectrograms indicate higher energy concentrations
• Formants visible as dark bands on spectrograms
  • Reflect vocal tract resonances
  • Crucial for identifying vowel qualities
• Voice onset time (VOT) measured on spectrograms
  • Time between stop release and onset of voicing
  • Distinguishes aspirated from unaspirated stops
• Transitions between speech sounds provide important cues
  • Formant transitions indicate place of articulation for consonants
  • Locus frequencies help identify consonant place of articulation
• Spectrogram reading skills include identifying
  • Voicing (presence of vertical striations)
  • Frication (high-frequency noise)
  • Bursts (vertical lines for stop releases)
  • Formant structures (horizontal bands for vowels)
  • Coarticulatory effects (changes in formant patterns due to adjacent sounds)

Advanced acoustic analysis techniques

• Fundamental frequency (F0) contour analysis
  • Reveals intonation patterns and pitch accents
  • Useful for studying prosody and tone languages
• Intensity patterns examination
  • Provides information about stress and prominence
  • Helps identify syllable boundaries
• Spectral tilt measurement
  • Indicates voice quality differences (breathy, creaky, modal)
  • Relevant for studying phonation types across languages
• Cepstral analysis
  • Separates source and filter components of speech
  • Useful for speaker identification and speech recognition
• Long-term average spectrum (LTAS)
  • Reveals overall spectral characteristics of a speaker's voice
  • Applied in voice quality assessment and speaker comparison

Transcription with IPA

IPA symbol categories and usage

• International Phonetic Alphabet (IPA) standardized system for representing sounds of all human languages
• IPA symbols categorized into
  • Pulmonic consonants (most common consonant sounds)
  • Non-pulmonic consonants (clicks, implosives, ejectives)
  • Vowels (monophthongs and diphthongs)
  • Diacritics (additional phonetic features)
• Broad transcription captures phonemic distinctions in a language
  • Represents only contrastive sound differences
  • Example English broad transcription /kæt/ for "cat"
• Narrow transcription includes more detailed phonetic information
  • Represents allophonic variations and fine phonetic details
  • Example English narrow transcription [kʰæt̚] for "cat" with aspiration and unreleased final stop

Diacritics and suprasegmental features

• Diacritics in IPA indicate secondary articulations
  • Nasalization (ã, ẽ)
  • Aspiration (pʰ, tʰ)
  • Lip-rounding (tʷ)
  • Velarization (ɫ)
  • Palatalization (tʲ)
• Suprasegmental features represented using specific IPA conventions
  • Stress marked with ˈ (primary) and ˌ (secondary)
  • Intonation patterns indicated with arrows (↗️ rising, ↘️ falling)
  • Tone marked with diacritics (á high, à low, ǎ rising, â falling)
• Length distinctions shown with ː for long sounds
  • Example iː vs i for long and short vowels

Developing transcription skills

• Proficiency in IPA transcription requires familiarity with articulatory descriptions of sounds and corresponding symbols
• Practice transcribing various languages including non-native sounds essential for developing accurate transcription skills
• Strategies for improving transcription abilities
  • Listen to and transcribe recordings of different languages
  • Compare transcriptions with native speakers or experts
  • Study acoustic properties of unfamiliar sounds
  • Practice producing non-native sounds to enhance perception
• Common challenges in IPA transcription
  • Distinguishing similar sounds (θ vs f)
  • Representing allophonic variations consistently
  • Transcribing unfamiliar sound systems (click consonants, tone languages)
• Resources for IPA practice and reference
  • Online IPA charts with audio samples
  • Language-specific pronunciation guides
  • Phonetics textbooks with transcription exercises