SLHS 2010 Final Exam Notes

SLHS 2010 Final Exam Study Guide

Volumes and Capacities

• Volumes vs. Capacities: Define and differentiate between lung volumes and lung capacities.

  • Lung volumes are discrete measurements; lung capacities are combinations of volumes.

• Tidal Volume (TV): The amount of air inhaled or exhaled during normal breathing. $TV \approx 500$ mL in adults.

• Inspiratory Reserve Volume (IRV): The अतिरिक्त amount of air that can be inhaled after a normal tidal volume. $IRV \approx 3000$ mL.

• Expiratory Reserve Volume (ERV): The अतिरिक्त amount of air that can be exhaled after a normal tidal volume. $ERV \approx 1100$ mL.

• Residual Volume (RV): The volume of air remaining in the lungs after a maximal exhalation. This air cannot be voluntarily expelled. $RV \approx 1200$ mL.

• Total Lung Capacity (TLC): The total volume of air the lungs can hold; the sum of all volumes. $TLC = TV + IRV + ERV + RV \approx 6000$ mL.

• Vital Capacity (VC): The total amount of air that can be exhaled after a maximal inhalation. $VC = TV + IRV + ERV \approx 4600$ mL.

Speech Breathing vs. Life Breathing

• Speech Breathing:

  • Involves shorter inhalation and prolonged exhalation to sustain speech.

  • Voluntary control is significant.

  • Requires precise control of respiratory muscles.

  • Larger volume of air typically inhaled than in life breathing.

• Life Breathing:

  • Involves roughly equal time for inhalation and exhalation.

  • Primarily involuntary.

  • Controlled by autonomic nervous system.

  • Purpose is solely gas exchange.

Inhalation and Exhalation

• Inhalation:

  • Diaphragm contracts and lowers, increasing thoracic cavity volume.

  • External intercostal muscles contract, raising the rib cage.

  • Increased volume leads to decreased pressure (Boyle's Law), causing air to rush in.

• Exhalation:

  • Diaphragm relaxes and rises, decreasing thoracic cavity volume.

  • Internal intercostal muscles contract (during active exhalation), lowering the rib cage.

  • Decreased volume leads to increased pressure (Boyle's Law), forcing air out.

• Boyle's Law: Pressure and volume are inversely proportional, at constant temperature. Mathematically, $P<em>1V</em>1 = P<em>2V</em>2$, where P is pressure and V is volume.

Laryngeal Bone

• Hyoid Bone: The only laryngeal bone.

• Location: Sits superior to the larynx; it is suspended by muscles and ligaments and does not articulate with any other bone.

Laryngeal Cartilages

• Nine Laryngeal Cartilages:

  • Thyroid Cartilage: The largest cartilage; forms the anterior and lateral walls of the larynx; shield-shaped.

  • Cricoid Cartilage: A ring-shaped cartilage; sits inferior to the thyroid cartilage and superior to the trachea.

  • Epiglottis: A leaf-shaped cartilage; folds over the larynx during swallowing to protect the airway.

  • Arytenoid Cartilages (2): Pyramid-shaped cartilages; sit on the superior border of the cricoid cartilage; crucial for vocal fold adduction and abduction.

  • Corniculate Cartilages (2): Small, cone-shaped cartilages; sit on the apex of the arytenoid cartilages.

  • Cuneiform Cartilages (2): Small, rod-shaped cartilages; embedded in the aryepiglottic folds; provide support.

Vocal Fold Layers

• Five Layers of Vocal Folds:

  • Epithelium: Thin, outer layer; provides a protective covering.

  • Lamina Propria (Superficial Layer): Also known as Reinke's space; contains loose fibrous components, like elastin, allows for vibration.

  • Lamina Propria (Intermediate Layer): Contains elastic fibers, contributes elasticity and support.

  • Lamina Propria (Deep Layer): Contains collagen fibers, provides support and structure.

  • Vocalis Muscle: The main body of the vocal fold; provides muscle contraction and relaxation.

Myoelastic Aerodynamic Theory of Phonation

• Myoelastic Aerodynamic Theory: Explains vocal fold oscillation as a combination of muscle (myo-) activity, tissue elasticity, and aerodynamic principles.

  • Muscle Activity: Muscles adduct the vocal folds.

  • Elasticity: Vocal folds have elastic properties that allow them to stretch and return to their original shape.

  • Aerodynamics: Air pressure and flow dynamics govern vocal fold movement.

    • Bernoulli Effect: As air passes between the adducted vocal folds, the velocity increases and pressure decreases, causing the folds to be sucked together.

Harmonics Calculation

• Given a fundamental frequency ($f_0$) and amplitude, calculate harmonics:

  • Frequencies of harmonics are integer multiples of $f<em>0$. For example, if $f</em>0 = 100$ Hz, the second harmonic is 200 Hz, the third is 300 Hz, etc.

  • Amplitudes of harmonics generally decrease as frequency increases.

Fundamental Frequency of Complex Harmonic Sound

• The fundamental frequency ($f_0$) of a complex harmonic sound is the greatest common divisor of the frequencies present in the sound.

• Alternatively, it is the inverse of the period (T) of the complex waveform: $f_0 = \frac{1}{T}$.

Changing Vocal Pitch

• Vocal Pitch Change: Achieved primarily by changing the tension and length of the vocal folds.

  • Increase Pitch: Tensing the vocal folds and/or increasing their length. The cricothyroid muscle is primarily responsible for pitch changes.

  • Decrease Pitch: Relaxing the vocal folds and/or decreasing their length.

Pitch Differences Between Speakers

• Pitch Differences between speakers: Varied due to vocal fold length, thickness, and tension.

  • Sex: Males typically have lower pitches than females due to longer and thicker vocal folds.

  • Age: Pitch generally decreases with age in males (due to vocal fold thickening) and increases in females (due to hormonal changes and vocal fold thinning after menopause).

Source Filter Theory

• Source-Filter Theory: Speech production is a two-stage process:

  • Source: Generates the raw sound.

    • Voiced Sounds: The source is vocal fold vibration (phonation).

    • Unvoiced Sounds: The source is turbulence created at a constriction in the vocal tract (e.g., /s/, /f/).

  • Filter: Modifies the sound produced by the source.

    • The vocal tract acts as a filter, shaping the sound by selectively amplifying certain frequencies (resonances or formants).

Voice Measurement Methods

• Voice Measurement Methods:

  • Acoustic Analysis: Measures frequency, intensity, and other acoustic parameters of the voice signal.

  • Aerodynamic Analysis: Measures airflow, air pressure, and other aerodynamic aspects of voice production.

  • Laryngoscopy: Visual examination of the larynx.

  • Stroboscopy: Visual examination of the larynx with stroboscopic light to assess vocal fold vibration.

Formants

• Formants: Resonant frequencies of the vocal tract that are amplified. They are dependent on the shape and size of the vocal tract.

• Formants are numbered from lowest to highest (F1, F2, F3, etc.).

• Formant frequencies are crucial for vowel identification.

Active and Passive Articulators

• Active Articulators: Parts of the vocal tract that move during speech production (e.g., tongue, lips, velum).

• Passive Articulators: Stationary parts of the vocal tract that active articulators contact (e.g., hard palate, alveolar ridge, teeth).

Vowel Production

• Vowel Production: Different vowels are produced by changing the shape of the vocal tract.

  • F1: Primarily influenced by tongue height; higher tongue position = lower F1, lower tongue position = higher F1.

  • F2: Primarily influenced by tongue advancement; front tongue position = higher F2, back tongue position = lower F2.

Relationship Between F1 & F2

• F1 & F2 Relationship: The relationship between F1 and F2 is crucial for vowel identification.

• The specific F1/F2 values for a given vowel can vary somewhat between speakers due to differences in vocal tract size and shape, but the relative relationship between the formants remains consistent within a language.

Acoustic Measurements & Articulatory Descriptions of Vowels

• Acoustic measurements of vowels (F1, F2) directly relate to articulatory descriptions (tongue height, tongue backness).

• For example, a high F1 and a back F2 would indicate a low, back vowel.

Differences in Formant Frequencies Between Speakers

• Differences in formant frequencies are due to:

  • Vocal tract length; shorter vocal tracts result in higher formant frequencies.

  • Vocal tract shape disparities.

Articulation

• Articulation: The process of physically producing speech sounds by movement of the articulators (tongue, lips, jaw).

• Purpose: To shape the vocal tract and produce specific sounds that convey linguistic meaning.

• Accomplishment: Achieved through precise coordination of articulatory movements.

Vowel vs. Consonant Production

• Vowel Production: Relatively open vocal tract; sound source is typically vocal fold vibration (voicing); characterized by formant frequencies.

• Consonant Production: Involves constriction or obstruction of the vocal tract; sound source can be voicing, turbulence, or a combination.

Manner, Place, and Voicing

• Manner of Articulation: How the sound is produced (e.g., stop, fricative, nasal).

• Place of Articulation: Where in the vocal tract the constriction is made (e.g., bilabial, alveolar, velar).

• Voicing: Whether the vocal folds are vibrating during the sound production (voiced vs. voiceless).

Consonant Types

• Stop Consonants: Complete closure of the vocal tract, followed by a release of air (e.g., /p/, /t/, /k/).

• Nasals: Closure of the oral cavity with the velum lowered to allow air to pass through the nasal cavity (e.g., /m/, /n/, /ŋ/).

• Fricatives: Narrow constriction in the vocal tract that creates turbulent airflow (e.g., /f/, /s/, /ʃ/).

• Affricates: A stop followed immediately by a fricative (e.g., /tʃ/, /dʒ/).

• Approximants: Slight constriction in the vocal tract, but not enough to cause turbulence (e.g., /r/, /l/).

• Glides: Rapidly articulated sounds that transition quickly into a vowel; also called semivowels (e.g., /w/, /j/).

Tongue and Lip Position in Vowel Production

• Tongue Tip Position: Contributes to vowel quality, especially in front vowels. For example, /i/ with a high, front tongue tip position.

• Lip Position: Rounding or spreading of the lips affects vowel quality, especially in back vowels. Example: /u/ with rounded lips.

Assimilation

• Assimilation: A sound becomes more similar to a neighboring sound.

• Example: "in possible" becomes "impossible" /ɪmˈpɑsəbəl/ due to assimilation of the /n/ to /m/.

Coarticulation

• Coarticulation: Overlapping of articulatory gestures during speech production; articulators are simultaneously completing movements for different phonemes.

• Effect on Speech Production: Can result in slight variations in the acoustic properties of sounds.

• Effect on Speech Perception: Listeners are generally unaware of coarticulation, but it provides cues that assist in speech perception.

Lack of Segmentability

• Lack of Segmentability: Difficulty in dividing the continuous speech stream into discrete phonemes because of coarticulation and other factors.

• Speech is perceived categorically, but the acoustics vary continuously.

Components of Prosody

• Components of Prosody:

  • Intonation: Variations in pitch.

  • Stress: Emphasis on certain syllables or words.

  • Timing/Rhythm: Durations of sounds, pauses, and overall speech rate.

Conduction vs. Transduction

• Conduction: The transmission of sound waves through a medium (air, bone, fluid) without a change in form.

• Transduction: The conversion of energy from one form to another (e.g., acoustic energy to mechanical energy, or mechanical energy to neural impulses).

Outer Ear Functions

• Outer Ear Functions:

  • Protection of the middle and inner ear.

  • Amplification of sound (especially in the 3-5 kHz range), due to resonance of the ear canal.

  • Sound Localization (pinna helps with localization).

• Landmark: The tympanic membrane (eardrum) is the landmark between the outer and middle ear.

Resonant Frequencies Calculation (Vocal Tract/Ear Canal)

• Resonant Frequencies Calculation: The vocal tract and ear canal can be modeled as tubes open at one end.

• The resonant frequencies (formants) can be calculated using the formula: $f = \frac{(2n-1)c}{4L}$, where:

  • $f$ = resonant frequency

  • $n$ = formant number (1, 2, 3, …)

  • $c$ = speed of sound (approximately 343 m/s)

  • $L$ = length of the tube (vocal tract or ear canal)

Middle Ear Structures and Functions

• Middle Ear Structures:

  • Tympanic Membrane (Eardrum): Vibrates in response to sound waves.

  • Ossicles (Malleus, Incus, Stapes): Three small bones that transmit vibrations from the tympanic membrane to the oval window of the cochlea.

  • Eustachian Tube: Connects the middle ear to the nasopharynx.

• Functions:

  • Tympanic Membrane: Receives sound.

  • Ossicles: Amplify and transmit vibrations.

  • Eustachian Tube: Equalizes pressure between the middle ear and the atmosphere.

Eustachian Tube Function

• Eustachian Tube Function: Equalizes air pressure in the middle ear with the outside atmospheric pressure.

• This is important for proper vibration of the tympanic membrane.

Impedance Matching

• Impedance Matching: The process of efficiently transferring sound energy from the air-filled middle ear to the fluid-filled inner ear.

• Necessity: Due to the difference in impedance (resistance to sound transmission) between air and fluid, most sound energy would be reflected if not for impedance matching.

Middle Ear Amplification and Attenuation

• Amplification:

  • Area difference between the tympanic membrane and the stapes footplate.

  • Lever action of the ossicles.

• Attenuation:

  • Acoustic Reflex: Contraction of the stapedius and tensor tympani muscles in response to loud sounds, which stiffens the ossicular chain and reduces sound transmission.

Interaural Timing and Level Differences

• Interaural Timing Differences (ITD): Differences in the arrival time of a sound at the two ears.

  • Used for localizing low-frequency sounds.

• Interaural Level Differences (ILD): Differences in the intensity of a sound at the two ears.

  • Used for localizing high-frequency sounds.

Cochlear Chambers

• Three Chambers of the Cochlea:

  • Scala Vestibuli: Upper chamber; contains perilymph.

  • Scala Media (Cochlear Duct): Middle chamber; contains endolymph; site of the Organ of Corti.

  • Scala Tympani: Lower chamber; contains perilymph.

Organ of Hearing

• Organ of Hearing: The Organ of Corti.

• Location: Located within the Scala Media (cochlear duct) of the cochlea.

• Resting Structure: Rests upon the basilar membrane.

• Sensory Receptor Cells: Hair cells (inner and outer hair cells).

Cochlear Movement

• Pattern of Movement: Traveling wave.

• Description: Sound entering the cochlea causes the basilar membrane to vibrate in a traveling wave pattern.

  • Acoustic Correlates: The amplitude and location of the peak of the traveling wave are related to the frequency and intensity of the sound.

Tonotopic Organization

• Tonotopic Organization: The basilar membrane is organized by frequency.

• Base: High frequencies are processed near the base of the cochlea (narrow and stiff).

• Apex: Low frequencies are processed near the apex of the cochlea (wide and flexible).

Inner and Outer Hair Cells

• Inner Hair Cells (IHCs):

  • Primary sensory receptors; responsible for transducing mechanical vibrations into electrical signals that are sent to the auditory nerve.

• Outer Hair Cells (OHCs):

  • Amplify the traveling wave and sharpen frequency tuning of the basilar membrane; exhibit electromotility.

Cochlear Transduction Sequence

• Cochlear Transduction:

  1. Sound vibrations enter the cochlea and create a traveling wave on the basilar membrane.

  2. Movement of the basilar membrane causes the stereocilia of the hair cells to bend.

  3. Bending of the stereocilia opens mechanically gated ion channels.

  4. Ions (primarily potassium) flow into the hair cells, causing depolarization.

  5. Depolarization triggers the release of neurotransmitters.

  6. Neurotransmitters stimulate the auditory nerve fibers.

Auditory Nerve Origin

• Auditory Nerve Origin: Begins at the base of the hair cells in the cochlea.

• Afferent fibers transmit auditory information from the cochlea to the brainstem.

Central Auditory System Structures

• Central Auditory System Structures:

  • Cochlear Nucleus

  • Superior Olivary Complex

  • Inferior Colliculus

  • Medial Geniculate Body

  • Auditory Cortex

Auditory Brainstem and Midbrain Structures

• Auditory Brainstem and Midbrain:

  • Cochlear Nucleus (CN)

  • Superior Olivary Complex (SOC)

  • Lateral Lemniscus (LL)

  • Inferior Colliculus (IC)

Afferent vs. Efferent Fibers

• Afferent Fibers: Transmit information from the cochlea to the brain (sensory information).

• Efferent Fibers: Transmit information from the brain to the cochlea (motor/modulatory information).

Auditory Cortex Location and Organization

• Location: Temporal lobe.

• Organization: Tonotopic organization; different frequencies are processed in different areas of the cortex.

Sound Aspects Conducted to Cortex

• Three Aspects of Sound:

  • Frequency (Pitch): Encoded by the location of neural activity along the basilar membrane and in the auditory cortex.

  • Amplitude (Loudness): Encoded by the firing rate of auditory nerve fibers.

  • Timing (Temporal Information): Encoded by the timing of neural firing.

Neural Response to Speech and Loudness Perception

• Neural Response to Speech: Neural response to speech is complex but generally corresponds to the acoustic features of speech, such as formant frequencies and transitions.

• Loudness and Frequency: Loudness perception is related to frequency; equal loudness curves (phon contours) show that different frequencies require different sound pressure levels to be perceived as equally loud.

Bottom-Up and Top-Down Processing

• Bottom-Up Processing: Analysis of the acoustic signal itself; relies on the acoustic features of the speech sounds.

• Top-Down Processing: Use of prior knowledge, context, and expectations to influence speech perception; "filling in the gaps" when the acoustic signal is degraded.

Talker Normalization

• Talker Normalization: The process of adjusting speech perception based on the characteristics of the speaker's voice.

• Two Sources of Information:

  • Indexical Information: Characteristics of the talker (e.g., vocal tract size, dialect).

  • Linguistic Information: The actual speech sounds being produced.

• Focus: We may need to focus on one more than the other depending on the situation; for example, in noisy environments, we might rely more on indexical information to understand the speaker.

Categorical Perception

• Categorical Perception (CP): The tendency to perceive sounds as belonging to distinct categories, even though there may be continuous variations along an acoustic continuum.

• Common Tasks:

  • Identification Task: Listeners are asked to identify a sound as belonging to a particular category.

  • Discrimination Task: Listeners are asked to discriminate between two sounds.

Categorical Perception Across Languages

• CP Across Languages: Categorical perception is not the same in all languages; it is influenced by the phonemic categories of a language.

• English/Spanish Studies:

  • Found that English speakers are better at categorically perceiving certain English phonemes, while Spanish speakers are better at categorically perceiving certain Spanish phonemes.

• Results: These findings indicate that CP is shaped by linguistic experience.

Motor Theory of Speech Perception

• Motor Theory:

  • Speech perception is based on the listener's knowledge of how speech sounds are produced.

  • Listeners perceive speech by unconsciously accessing their own articulatory gestures.

  • Speech perception is different from the perception of other auditory sounds because it relies on specialized motor mechanisms.

Auditory Theories of Speech Perception

• Auditory Theories: These theories posits that:

  • Speech perception relies primarily on auditory processing of the acoustic signal.

  • Listeners extract acoustic features from the speech signal and map them onto phonemic categories.

  • Speech perception is not fundamentally different from the perception of other auditory sounds; it uses the same general auditory mechanisms.