Aerodynamic Aspects of Speech

The amount of air needed to produce and sustain speech is not much different from the amount used in normal, quiet breathing.

Air is supplied by the lungs, it valved and modified to produce various speech sounds and create diffent resonatory effects.

Changes in the rate of airflow, its volume, and its pressure, result in necessary modifications to produce different speech sounds.

System of Valves:
1.  vocal folds:  opening and closing change the flow of air and its pressure.
2.  The velopharyngeal mechanism:  couples and uncouples the oral/nasal cavity
3.  Oral cavity and Lips:  various constrictions of the oral cavity and closure of the lips maximizes, minimizes and eliminates airflow through the oral cavity.

Airflow
Air moves from a region of greater pressure to a region of lower pressure.  Because of Boyles law, pressure and volume are inversely related.  As the lungs inflate, pressure in the lungs go down and ir rushes in and vice versa.

Subglottic air pressure:  Aerodynamic Myo-elastic theory of speech production.  Build up of air pressure.

Relationship with articulation:
    Pressure consonants:  Plosives and fricatives because of constriction of the vocal tract causes increased pressure.  Pressure and flow are inversely related:  greater pressure where the constriction is smaller.
    Voiceless consonants have greatest intraoral breath pressure.  Because the subglottic air pressure is lost at the level of the vocal folds for voice consonants do not have the build up of air that voiceless (glottis is closed off) does.  Children have greater intraoral breath pressure than audlts.
Plosive and fricatives the most
Nasals, glides, and liquids have limited intraoral breath pressure

Our air flow mechanism is Pulmonic egressive airestream.

Other languages use other airstream mechanisms such as
    1.  Glottic airstream mechanism (Native American and African)
       - air above the larynx (in a supralaryngeal chamber in which air pressure is increased) is used to initiate the speech sounds.  The sound released is called ejective.
    2.  Glottic ingressive airstream (African) Air is sucked inward.  The sound is called implosives.
    3.  Velaric airstream mechanism:  (African)  air is trapped in the oral cavity by the tongue and the sound produced is a click.

Pathologies:
Vocal fold Paralysis
-Can't build sufficient subglottic air pressure; excessive air leakage resulting in a breathy voice.
Cleft Palate insufficient velopharyngeal closure to produce nasality
Respiratory disorders: inadequate breath support and loudness

Acoustics:  the physical properties of sound.
Frequency:  number of vibration per unit of time
    Speech:  vowels, liquids and glides:  low to mid frequency
                   Nasals: low
                    Strident fricatives and affricatives:  High
                    Stops:  wide range:  alveolars-mid to high; plosive: low; velars: mild
   Pure tone:  one frequency that repeats itself
Complex tones:  more than one frequency
Periodic:  the pattern repeats itself
Aperiodic:  no pattern of vibration
Spectrum:  Pattern of physical energy across a frequency range: Different sounds have different spectra
Pitch psychological component of frequency
Amplitude:  intensity; magnitude of the vibrations; greater the magnitude of vibration the higher the amplitude and greater the loudness (psychological component)
    Vowels:  greatest amplitude (Low vowels most intense)
    Glides and liquids: more intense than other classes of sound
    Stridents/fricatives affricatives, and nasals  are of moderate intensity,
    stops and nonstrident fricatives are among the weakest
Duration:  measure of time during which vibrations are sustaned
    Vowels longest;
Glides, liquids are short to moderate;
strident fricatives and affricates moderate;
nonstrident fricatives short to moderate;
nasal sounds short to moderate;
stops shortest

Age and gender affect acoustic properties of speech

Suprasegmental Aspects
1.  Pitch- pitch variations suggest differences in meaning; intonation are pitc contours; Emotional state, stress pattern employed; tongue position affect pitch: High vowels have the higher fundamental frequency
Pitch can signal new information; Tonal languages

2.  Stress- gives prominence to certain syllables.  The vowel segment is primarily stressed
    Stressed syllables have :greater vocal intensity; greater duration; produced with higher pitch 
May be used to emphasize parts of an utterance, may be used to distinguish non/verb forms  ie. convict
Contrastive stress: Give me the blue pen
When stress changes  "object" the vowel can become neutralized in the unstressed syllable.
English is a stress-timed languae:  stressed syllables tend to be produced at regular intervals.

3. Rate of speech:  affects prosodic features: Increased rate can negatively affect sound productions:  eliminates pauses, decreases precision or articulatory movment; reduces vowel duration.

4.  Juncture:  pauses that make semantic or grammatical distinctions:  "John, let us do it vs. John let us do it:
Cocktail vs cock tail; may signal new information.
 

Theories:
Theory of naturalness and markedness:
Dertain segments are more natural (more common among the languages of the world) than others.  A nautral segment is also unmarked.  Unmarked sounds occur earlier in the speech of children.
    Voiceless obstruents are more natural than voiced obstruents (stops, fricatives, and affricatives)
    Obstruents are more natural than sonorants.
    Stops are more natural than fricatives
    Fricatives are more natural than affricatives
    Low front vowels are most natural of the vowels
    Closed-tense vowelsa are more natural than open lax vowels
    Anterior consonatns are more natural than nonanterior consonants

Children tend to make fewer mistakes on more natural sounds.
Children master a more natural syllable structure (CV) earlier than less natural syllable structoures (CVC)

Processes ten to move toward naturalness:  FCD creats CV type syllable type
Stopping of fricatives
Errors tend to eliminate markedness

Linear vs Nonlinear
Linear theories state that the segmental properties or features of phonemes are independent of each other and may combine with another segment.  The features are independent characteristics of the phonemes with no hierarchical organization

New theories (Nonlinear) address apsects of phonology not addressed in the linear theories
    Effects of prosody (stress, tone, intonation) which influence speech beyond the segment
    Address the level of the syllable
    Had some sort of hierarchy that organizes the segmental and suprasegmental properties of sound

Metric:
    Metric theory examines the representaion of the syllable structure and analysis of stress patterns.
The syllable and its expanded structure is th main vehicle of prosody-- the rhythm of speech
Stress patterns are represente din terms of branching tree where one brance is labeld S for strnger and W for weaker

Metrical phonology is reponsible for the insight that phonological representaions have hierarchiacal structure much as do syntactic representation.

Syntax                                                                                Phonology

NP        VP                                                                            Syllable
 
        V        NP                                                        onset                     rhyme
John Saw the ball                                                                         nucleus            coda
 
 

French literature`                                W        S
      2       1                                   French      literature
French Literature Teacher
  3          1                 2                                                            S                     W
Old French Literature Teacher                                         W         S
2      4         1                 3                                              French Literature   Teacher
 

                                           W                 S
                                                        S             W
                                                   W     S
                                       old    Fr      Lit          Teacher
 

Feature Geometry
Proposes that feature combinations of a segment are also hierarchiacally organized.  Feature geometry attempts to explain why some features are affected by assimiliation processes (known as spreading) while others are affected by neutralization or deletion processes (known as delinking)

In accordance with principles of nonlinear phonologies, feature geometry utilizes hierarchically orgnaized levels of representation called tiers.  The tiers interact with one another.  Some features are designated as nodes, which means that they may dominate more than one other feature and serve as a link between the dominated feature and higher levels of representation.

Place node serves as a link between the labial, coronal, dorsal, and radical nodes and root nodes.  Features at a higher level of representation are said to dominate other features.
 (laryngeal
        s.g. = spread glottis (e.g., voiceless aspirated stops)
        c.g. = constricted glottis vocal folds are tightly closed: glottal stops)
(Tongue root
    Radical sounds in which the root of the tongue is advanced or retracted:  pharyngeal and pharyngealized consonants-not typical for Ame. English souds)
    Advanced tongue root--sounds in whcih the tongue root s advanced (high vowels and consonants are blank for this feature)

Newer theories primarily add to our knowledge of phonology rather than replace the older theories.

Empirical status of phonologica concepts.
Though typically asserted as such, phonological productions normally may not be rule-governed.  Experts extract phonological behaviors from patterned behaviors; this does not mean that the speakers follow those rules.