Unit 2: Description of Speech Sounds

Non segmental: Intensity, pitch and quality

Intensity (Loudness)

Intensity refers to the physical energy or power behind the speech signal.

• Physical Basis: It is determined by the subglottal air pressure (the pressure of air built up below the vocal folds). Higher pressure equals higher intensity.
• Perceptual Correlate: We perceive intensity as Loudness.
• Role in Communication:
  • Emphasis: We increase intensity to stress a specific word (e.g., “I said now!”).
  • Distance/Environment: We adjust intensity based on the size of the room or background noise.
• Issues in Hearing Impairment (HI): Children with HI often struggle to regulate intensity because they cannot monitor their own volume. They may speak in a whisper or shout inappropriately.

Pitch (Frequency)

Pitch is the most distinct non-segmental feature, providing the “melody” of speech.

• Physical Basis: It is determined by the Fundamental Frequency ($F_0$), which is the speed at which the vocal folds vibrate.
  • Faster vibration = Higher pitch.
  • Slower vibration = Lower pitch.
• Perceptual Correlate: We perceive frequency as Pitch.
• Role in Communication:
  • Intonation: Changing pitch to signal a question vs. a statement.
  • Emotion: Higher pitch often signals excitement or anger; lower pitch can signal sadness or authority.
• Issues in Hearing Impairment (HI): Lack of auditory feedback often leads to a “monotone” voice or a pitch that is abnormally high (falsetto) as the child tries to “feel” the vibration in their larynx.

Quality (Timbre)

Quality is the “texture” of the voice that allows you to distinguish one person’s voice from another, even if they are saying the same word at the same pitch and loudness.

• Physical Basis: It is determined by the Spectrum of the sound—the way the vocal tract (throat, mouth, nose) resonates and filters the sound produced by the larynx.
• Perceptual Correlate: We perceive this as Timbre or Vocal Quality.
• Descriptors of Quality:
  • Breathy: Air escaping through the vocal folds (often used for secrets or due to weakness).
  • Harsh/Hoarse: Irregular vibration of the vocal folds.
  • Nasal: Too much air escaping through the nose (Hypernasality).
• Issues in Hearing Impairment (HI): Because the child cannot hear the “balance” of resonance, their speech quality may become breathy or excessively nasal.

Parameter	Physical Property	How we Hear it	Controlled By
Intensity	Amplitude/Air Pressure	Loudness	Respiratory System
Pitch	Frequency of Vibration	Melody	Phonatory System
Quality	Spectrum/Resonance	Timbre	Resonatory System

The Interdependence of Parameters

In normal speech, these three do not act in isolation. For example, when we Stress a word:

1. Intensity increases (it gets louder).
2. Pitch usually rises.
3. Duration (another non-segmental) increases (we hold the word longer).

For a child with a hearing disability, the goal of speech therapy is often to help them decouple these—learning, for instance, that they can speak louder without necessarily raising their pitch.

Segmental aspects of speech: Definition of consonants, vowels, diphthong and blends

Vowels

Vowels are speech sounds produced with a relatively open vocal tract. There is no significant constriction or blockage of airflow from the lungs through the mouth.

• Definition: A voiced sound where the air passes freely through the oral cavity.
• Key Characteristics:
  • They form the nucleus (center) of almost every syllable.
  • They are highly resonant and carry the most acoustic energy.
  • Classification: Based on tongue height (high/low), tongue advancement (front/back), and lip rounding.
• Examples: /a/ as in “father,” /i/ as in “see,” /u/ as in “blue.”

Consonants

Consonants are speech sounds produced by constricting or closing the vocal tract at one or more points.

• Definition: Sounds characterized by an obstruction of the breath stream, either partial or complete.
• Key Characteristics:
  • They provide the “edges” or “frames” for syllables, helping listeners distinguish words.
  • Classification (The PVC Framework):
    1. Place: Where the obstruction occurs (e.g., Bilabial – lips; Alveolar – behind teeth).
    2. Voice: Whether vocal folds vibrate (Voiced /b/ vs. Voiceless /p/).
    3. Manner: How the air escapes (e.g., Stops /t/, Fricatives /s/, Nasals /m/).
• Examples: /p/, /s/, /m/, /k/.

Diphthongs

A diphthong is a complex speech sound that begins as one vowel and glides smoothly into another vowel within the same syllable.

• Definition: A “double vowel” sound where the articulators (tongue and lips) move from one position to another.
• Key Characteristics:
  • Though they involve two vowel positions, they are treated as a single phoneme.
  • The first element is usually stronger and longer than the second.
• Common Examples:
  • /ai/ as in “Bye“
  • /au/ as in “House”
  • /oi/ as in “Boy“

Blends (Consonant Clusters)

A blend consists of two or more consonants appearing together in a word, where each individual sound is still heard.

• Definition: A group of consonants that cluster together without a vowel between them, yet retain their distinct phonetic identities.
• Key Characteristics:
  • They can occur at the beginning (Initial Blends) or end (Final Blends) of words.
  • Unlike Digraphs (where two letters make one new sound like /sh/), in a blend, you can hear every letter’s sound.
• Examples:
  • “Bl” in blue (/b/ + /l/)
  • “Str” in street (/s/ + /t/ + /r/)
  • “St” in best (/s/ + /t/)

Feature	Airflow	Complexity	Example
Vowel	Completely open	Simple/Pure	“Ah”
Consonant	Constricted/Blocked	Specific/Targeted	“T”
Diphthong	Open but moving	Glide (2-in-1)	“Oil”
Blend	Multiple constrictions	Sequence of sounds	“Crisp”

Relevance to Speech Training

For children with hearing impairment, vowels are often easier to acquire because they are louder and have more duration. Consonants, especially blends, are more difficult because they are quieter and require high-frequency hearing to distinguish (e.g., the difference between “sl-” and “st-“). Diphthongs require precise motor control to achieve the “glide” between two vowel targets.

Classification of consonants – place, manner, voicing

Voicing (State of the Glottis)

Voicing refers to whether or not the vocal folds (vocal cords) are vibrating during the production of the sound.

• Voiced Consonants: The vocal folds are held close together and vibrate as air passes through.
  • Examples: /b/, /d/, /g/, /v/, /z/, /m/.
• Voiceless (Unvoiced) Consonants: The vocal folds are kept apart, allowing air to pass freely through the glottis without vibration.
  • Examples: /p/, /t/, /k/, /f/, /s/, /h/.

Place of Articulation (Location)

This identifies where in the vocal tract the obstruction occurs—which “articulators” are touching or coming close to each other.

Place	Description	Examples
Bilabial	Using both lips.	/p/, /b/, /m/
Labiodental	Lower lip touching upper teeth.	/f/, /v/
Linguadental	Tongue tip between or behind the teeth.	/th/ (thin, then)
Alveolar	Tongue tip touching the ridge behind upper teeth.	/t/, /d/, /s/, /n/
Palatal	Tongue body touching the hard palate (roof of mouth).	/sh/, /ch/, /j/
Velar	Back of the tongue touching the soft palate (velum).	/k/, /g/, /ng/
Glottal	Sound produced at the level of the vocal folds.	/h/

Manner of Articulation (Method)

This describes how the breath stream is controlled or obstructed to create the sound.

• Stops (Plosives): The airflow is completely blocked and then released with a small “explosion” of air.
  • Examples: /p, b, t, d, k, g/
• Fricatives: The vocal tract is narrowed so much that the air creates a “hissing” or friction sound as it passes through.
  • Examples: /f, v, s, z, sh, th/
• Affricates: A combination of a stop and a fricative; it begins with a stop and releases into a fricative.
  • Examples: /ch/ (as in church), /j/ (as in judge)
• Nasals: The oral cavity is closed, but the soft palate is lowered, allowing air to escape through the nose.
  • Examples: /m, n, ng/
• Liquids/Glides (Semivowels): These involve less constriction than other consonants and have a vowel-like quality.
  • Examples: /l, r/ (Liquids), /w, y/ (Glides)

By combining these three, you can identify any sound. For example, /b/ is a Voiced Bilabial Stop.

Manner	Bilabial	Labiodental	Alveolar	Palatal	Velar
Stop	p, b		t, d		k, g
Fricative		f, v	s, z	sh
Nasal	m

Significance for Children with Hearing Impairment

Voicing: Often hard to distinguish by ear; children are taught to feel the “buzz” on the throat for voiced sounds.

Place: Highly visible places (Bilabial, Labiodental) are usually learned first because the child can use speechreading (lip-reading) to see the target.

Manner: Fricatives (like /s/) are high-frequency sounds that are often the first to be lost if a child’s hearing aid is not adjusted properly.

Classification of vowels

The Four Parameters of Vowel Classification

Speech-language pathologists and linguists use four primary dimensions to classify vowels:

A. Tongue Height (Vertical Position)

This refers to how close the highest point of the tongue is to the roof of the mouth.

• High Vowels: The tongue is close to the palate (e.g., /i/ as in “bee,” /u/ as in “blue”).
• Mid Vowels: The tongue is in an intermediate position (e.g., /e/ as in “bet,” /o/ as in “boat”).
• Low Vowels: The tongue is low in the mouth, and the jaw is usually more open (e.g., /a/ as in “father”).

B. Tongue Advancement (Horizontal Position)

This refers to how far forward or back the tongue is in the mouth.

• Front Vowels: The tongue is pushed toward the front (e.g., /i/ as in “see,” /æ/ as in “cat”).
• Central Vowels: The tongue is in a neutral position (e.g., /ə/ or “schwa” as in the first sound of “about”).
• Back Vowels: The tongue is retracted toward the back (e.g., /u/ as in “too,” /ɔ/ as in “saw”).

C. Lip Rounding

The shape of the lips significantly alters the resonance of the vowel.

• Rounded: Lips form a circular shape (e.g., /u/, /o/).
• Unrounded (Spread/Neutral): Lips are flat or retracted (e.g., /i/, /e/, /a/).

D. Tenseness (Tense vs. Lax)

This refers to the degree of muscular effort and the duration of the sound.

• Tense Vowels: Longer duration and more muscular tension (e.g., /i/ as in “heat”).
• Lax Vowels: Shorter and more relaxed (e.g., /ɪ/ as in “hit”).

The Vowel Quadrilateral

The vowel quadrilateral is a schematic representation of the oral cavity. It maps where the tongue is positioned for each vowel.

Position	Front	Central	Back
High	/i/ (eat)		/u/ (boot)
Mid	/e/ (met)	/ə/ (about)	/o/ (note)
Low	/æ/ (cat)

Types of Vowels

Monophthongs: Pure vowels where the tongue remains stationary throughout the sound (e.g., “ah”).

Diphthongs: Vowels that transition from one position to another (e.g., the /ai/ in “buy”).

Nasalized Vowels: Vowels produced with the soft palate lowered, allowing air to escape through the nose (often occurs when a vowel is next to a nasal consonant like /m/ or /n/).

Clinical Significance for Hearing Impairment

Vowel Neutralization: This is a common issue in the speech of children with HI. Because they cannot hear the subtle differences in tongue position, all vowels tend to sound like the central “schwa” (/ə/).

Visual Cues: While tongue height is hard to see, lip rounding and jaw opening are highly visible. Educators use these visual cues to help children differentiate between /i/ (wide lips, closed jaw) and /a/ (neutral lips, open jaw).

Acoustic Power: Vowels are the loudest parts of speech. In speech training, we often start with vowels because they are easier for the child to detect using their residual hearing.

Supra-segmental: Intonation, stress, pause, etc.

Intonation

Intonation is the variation of pitch over a phrase or sentence. It is often referred to as the “melody” of speech.

• Function: It signals the speaker’s intent and grammatical structure.
• Common Patterns:
  • Falling Intonation: Usually indicates a statement or the end of a thought (e.g., “I am going home.”).
  • Rising Intonation: Usually indicates a question or uncertainty (e.g., “Are you coming?”).
• HI Issue: Children with hearing impairment often produce “monotone” speech or inappropriate pitch breaks because they cannot perceive these melodic shifts.

Stress

Stress is the emphasis placed on a specific syllable within a word or a specific word within a sentence.

• Word Stress: Distinguishes meaning between identical words. For example:
  • CON-tent (noun, meaning subject matter) vs. con-TENT (adjective, meaning happy).
• Sentence Stress: Highlights the most important information.
  • “I didn’t take the book” (Someone else did).
  • “I didn’t take the BOOK” (I took something else).
• Mechanism: Stress is achieved by increasing intensity (loudness), raising pitch, and lengthening the duration of the syllable.

Pause (Juncture)

A pause is a momentary silence or break in the stream of speech.

• Function:
  • Syntactic: To separate phrases or sentences so the listener can process information.
  • Emphasis: To create anticipation before an important word.
  • Juncture: Small pauses that differentiate words (e.g., “a name” vs. “an aim”).
• HI Issue: Students with HI may have “labored” speech where they pause inappropriately to take a breath or to find the correct articulatory position, which breaks the flow of communication.

Rate of Speech

Rate refers to the speed at which a person speaks, typically measured in words per minute.

• Function: Reflects the speaker’s emotional state (fast for excitement/anxiety, slow for deliberation/sadness).
• HI Issue: Speech is often significantly slower in the HI population due to the high cognitive and motor effort required to produce each sound.

Rhythm

Rhythm is the patterned recurrence of stressed and unstressed syllables.

• English Rhythm: English is a stress-timed language, meaning the duration between stressed syllables remains relatively constant.
• Significance: Correct rhythm helps the listener “predict” when the next important word is coming, which is vital for intelligibility.

Feature	Primary Physical Change	Primary Meaning
Intonation	Pitch / Frequency	Grammar and Emotion
Stress	Intensity and Duration	Emphasis and Word Class
Pause	Silence / Time	Structure and Clarity
Rate	Velocity	State of Mind / Fluency