Phonetics: Speech Sounds, Production, and Classification

Phonetics Basics

• Phonetics: The study of speech sounds.

• Types of Phonetics:

  • Articulatory Phonetics: Study of how the human vocal tract produces sounds.

  • Acoustic Phonetics: Study of the physical properties of sounds.

Speech Sounds (Segments/Phones)

• Speech sounds are individual, discrete units (segments or phones) that form words but have no inherent meaning.

• The number of sounds is not always the same as the number of letters; e.g., "cat" [kæt] (3 sounds, 3 letters), "ox" [ɑks] (3 sounds, 2 letters).

• Languages vary in sound inventory (e.g., Rotokas: 11, English: 40, Taa: 87-164).

• Sound choices are constrained by production (what's physically possible) and perception (how distinct sounds need to be).

• Babies lose the ability to distinguish all possible speech sounds with age, making foreign sound perception difficult.

• Quechua example: Distinguishes six 'k' sounds based on place of articulation (velar/uvular) and timing of airflow (voiceless/aspirated/ejective).

Evidence for Segments

• Alphabetic Writing Systems: Roughly one symbol represents one segment.

• Consistent Perceptions: Speakers consistently perceive the number of segments in words (e.g., "desk" [dɛsk] = 4, "knot" [nɑt] = 3, "sheep" [ʃip] = 3).

• Recurring Sound Elements: Speech contains recognizable sound elements arranged in various ways (e.g., bad, dab).

• Speech Errors: Involve transposition of segments (e.g., "fire and brimstone" $\rightarrow$ "bire and frimstone").

Sounds and Spelling (Orthography)

• English orthography is unsystematic; no consistent one-to-one letter-to-sound correspondence.

• Problems:

  • Two letters = one sound (e.g., "th" for [ð] or [θ]).

  • One letter = two sounds (e.g., "x" for [ks]).

  • Different letters for the same sound (e.g., "s" or "c" for [s]).

  • Same letters for different sounds (e.g., "c" for [s] or [k]).

Phonetic Transcription

• Linguists use phonetic symbols for consistent, unambiguous representation.

• International Phonetic Alphabet (IPA): A universal system where one symbol always represents one speech sound.

• Transcriptions are enclosed in square brackets [ ] (e.g., [tæks]).

Speech Sound Production: Vocal Tract Anatomy

• Mechanism: Air supply (lungs) $\rightarrow$ sound source (vocal folds in larynx) $\rightarrow$ filters (pharynx, oral cavity, nasal cavity).

• Pulmonic Egressive: Most speech sounds are produced by expelling air from the lungs.

• Larynx: Contains the vocal folds.

• Glottis: The space between the vocal folds.

• Voiced vs. Voiceless: Determines if sound is produced.

  • Voiceless: Glottis is open, vocal folds apart, air passes through unhindered (e.g., [f], [s]).

  • Voiced: Glottis is closed and vocal folds vibrate as air passes through, producing periodic sound waves (voicing) (e.g., [v], [z]).

Sound Classes: Consonants vs. Vowels

• Consonants:

  • More constricted articulation.

  • Less sonorous (quieter).

  • Can be voiced or voiceless.

  • Periphery of the syllable.

• Vowels:

  • Open (unconstricted) articulation.

  • More sonorous (louder).

  • Usually voiced.

  • Core/nucleus of the syllable.

• Sonority: Acoustic measure of how "powerful" a sound is (louder, longer lasting).

Syllables

• A syllable is a peak of sonority (usually a vowel) surrounded by less sonorous segments.

• The peak of sonority is called the nucleus of the syllable.

• The number of vowels usually determines the number of syllables (e.g., "go" (1), "laughing" (2), "telephone" (3)).

Glides (Semivowels/Semiconsonants)

• Share properties of both consonants and vowels.

• Articulation is like vowels (rapid), but they do not form the syllable nucleus.

• Examples: [j] (y) and [w] (w).

Vowels and Diphthongs

• Simple Vowel: Does not show a noticeable change in quality during its production (e.g., [ɪ] in "pit").

• Diphthong: Shows a noticeable change in quality, starting with a simple vowel and ending in a glide (di- = two).

  • Major Diphthongs: More extreme change (e.g., [aj] in "buy").

  • Minor Diphthongs: Less extreme change (e.g., [ej] in "play").

Vowel Articulation

• Vowels are voiced sounds produced by changing tongue position and lip rounding.

• Parameters:

  • Tongue Height: High (e.g., [i]), Mid (e.g., [e]), Low (e.g., [æ]).

  • Tongue Frontness/Backness: Front (e.g., [i]), Central (e.g., [ʌ]), Back (e.g., [u]).

  • Lip Rounding: Pursed lips (rounded, e.g., [u]), unpursed (unrounded). All back, non-low vowels in English are typically rounded.

• Tense vs. Lax Vowels:

  • Tense Vowels: Greater vocal tract constriction, longer duration. Monosyllabic words can only end with tense vowels.

  • Lax Vowels: Lesser vocal tract constriction, shorter duration.

• Schwa ([ə]): A mid/central/unrounded/lax vowel; a reduced vowel with brief duration, always occurring in an unstressed syllable (e.g., "about" [əbawt]).

• A vowel chart visually represents these articulation parameters.

  Diphthongs

  Symbol	Start Position	End Position	Example
  aj	Low central unrounded tense → High front unrounded	my
  aw	Low central unrounded tense → High back rounded	now
  oj	Mid back rounded tense → High front unrounded	boy
  ej	Mid front unrounded tense → High front unrounded	say
  ow	Mid back rounded tense → High back rounded	go

  Simple