Voice Assessment: Instrumental

Instrumental Analysis of Voice Electromyographic assessment: direct measure of muscle activity; used for localization of muscle Aerodynamic assessment: 1. airflow rate & volume 2. subglottal (intraoral) pressure 3. laryngeal resistance 4. phonation threshold pressure

Instrumental Analysis of Voice Acoustic recording & analysis: 1. fundamental frequency (Fo) 2. intensity (dB SPL) 3. signal/ noise ratio 4. perturbation measures 5. spectral frequencies Electroglottography: measure of vocal fold contact area Photoglottography: measure of glottal area

Why do instrumentation evaluation? Contributes to the diagnosis, etiology and severity of the disorder, Allows perceptual measures to be objectified (i.e documentable), Instrumental evaluations are “noninvasive”, Baseline for documentation of progress,

Electroglottography Noninvasive, inexpensive, Demonstrates relative contact of the vocal folds during a glottal cycle, No information concerning area of glottal opening, Small electrodes on neck; glottis opens= impedance rises, glottis closes= impedance falls

Electrodes Glottis EGG Vocal fold contact area Electroglottograph electronics Vocal fold contact area Lines between electrodes represent the electrical current traversing through the v.f.’s

EGG Signal (inverse filtered) 1000 Airflow 68 MSEC EGG Opening (upward trace); Closing (downward trace) v.f.’s touch (close) = greater current

Width of area of glottis Glottogram OPEN Point of max opening Width of area of glottis (% of Maximum) CLOSED Opening Closing Closed Phase Open Phase 1 Cycle (T)

EGG: Normal & Disordered Glottal Waves A. Normal glottal width function A. B. Right Vocal fold Right Vocal fold Midline Midline Relative distance from midline Relative distance from midline Left Vocal fold Left Vocal fold Time of frame number B. Left recurrent nerve paralysis (Left never reaches midline & greater excursion; right fold crosses midline)

Electromyography Electrodes are either surface or needle, Needle inserted into specific muscles What do we look for? 1. onset & offset of muscle activity 2. pattern of muscle activity 4. amplitude of muscle activity 5. spont. bursts of activity Useful for voice problems with neurological or neuromuscular etiology.

EMG: Hooked Wire Electrode

EMG Vowel Production CV Combos CT Voice CT Voice Long relaxation time Buildup of EMG activity in CT ba ba ba bababa da da dadada

Aerodynamic Define vocal efficiency through airflow rates & pressure changes, Airflow rates: flow of air through the glottis, measured using pneumotachography & body plethesmography Subglottal pressure: driving pressure underneath the folds, pitot tube & pressure transducer, tube placed in the oral cavity, invasive method = esophageal balloon

Aerodynamic Laryngeal resistance: peak intraoral pressure divided by peak flow rate, reflects the overall resistance of the glottis, Phonation threshold pressure: minimal pressure to set v.f.’s into oscillation

Glottal Resistance A. Increased in subglottal pressure to overcome increase in glottal resistance B. Larynx offers increased resistance to airflow as folds are placed under increased tension Intratracheal Pressure (cm H20) Glottal resistance (dynes/se/cm) Fundamental Frequency (% of Freq. range) Fundamental Frequency (% of Freq. range) *30% of F0= Most efficient function of the larynx or habitual pitch

Importance of aerodynamic results? Results are a reflection of the valving activity of the larynx, Represents v.f. configuration, movement, structure & function, Intraoral pressure, transglottal airflow, & laryngeal resistance: 1. Discriminate normal & pathologic voice function, 2. Assess severity 3. Suggest implications for the diagnostic source of voice pathology

Acoustic Fundamental frequency: rate of vibration of the vocal folds, expressed in Hertz, or cycles per second, measure on sustained vowel or connected speech, Visipitch, C-Speech, CSL Perturbation measures: cycle-to-cycle variation in a signal; jitter (frequency) & Shimmer (amplitude), Signal to noise ratio: a measure of the energy in the voice signal over the noise energy in the voice signal, greater harmonic energy in voice= better voice quality,

Acoustic Intensity: SPL (Sound Pressure Level), measure mean and range intensity, Sound level meter or acoustic analysis programs Spectral analysis: displays glottal sound source & filtered characteristics of the speech signal across time, useful to analyze changes in the spectral characteristics of the voice sound, C-Speech, CSL

Spectographs Aperiodic v.f. vibration is evident by the irregularity of the spacing of the vertical voice bars

Spectograhs: Voice Quality Normal Nasal Breathy Harsh Hoarse

Spectographs: Vocal Nodules A. Vocal Nodule B. Aperiodic vocal fold vibration & Noise C. Six weeks post surgery

Importance of Acoustic Measures Provide objective & noninvasive measures of vocal function Normative values help you discriminate normal and pathological voice attributes Measure change in vocal performance over time Indirect inference about the severity of voice No acoustic measures can differentially diagnose the source of the voice pathology

Case # 1 41 year old attorney 4 months dysphonia Problem began after severe URI chronic coughing & clearing Long history of cigarette smoking ( 1 pack per day) Moderate alcohol consumption Voice abuser: home, sporting event, work

Examination Findings Mild-moderately hoarse- breathy Dramatic pitch decrease (2 months) Syllables per breath were normal Maximum phonation time = 16 seconds Acoustic: F0= 105 hz Jitter = 1.4% Shimmer = .33 dB S/N ratio = 12.7 dB

Examination Findings Aerodynamic: Mean airflow (l/sec)= 798 cc /sec Subglottal pressure = 20 cm H20 Glottal resistence= 20 cm H20/lps compressoin force between vocal folds during closed phase of vibration

Diagnosis Bilateral true vocal fold hemorrhagic polyps secondary to voice misuse & abuse

Readings Colton & Casper Ch.7 (Last half particularly)