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Instrumental Assessment SPPA 6400 Voice Disorders: Tasko
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Ways to Assess the Utility of Instrumentation Does it help detect the existence of a voice problem? Can it help establish the severity of progression of a voice problem? Can it help differentially diagnose a voice problem? Can it be used as a treatment tool, in the form of biofeedback, behavioral modification or patient education? SPPA 6400 Voice Disorders: Tasko
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Selected Instrumental Techniques Acoustic Analysis Aerodynamic Analysis Laryngeal Imaging SPPA 6400 Voice Disorders: Tasko
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Acoustic Analysis of Voice SPPA 6400 Voice Disorders: Tasko
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Recording Considerations Equipment – Microphone and preamplifier setup Handheld, headset, dynamic mic, condenser mic – Device onto which signal is recorded Computer, dedicated recording device Optimizing Recording – Microphone Position – Recording levels – Digital-to-audio conversion settings SPPA 6400 Voice Disorders: Tasko
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SPPA 6400 Voice Disorders Analysis Considerations Real-time analysis Examples – Sound level meter – Visi-pitch – Real-time spectrograms “Off-line” analysis (analysis after data is collected) Examples – Computerized speech Lab (CSL), MDVP – Cspeech (tf32) – Praat – Speech Tool
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Voice Signal Typing Type I – Quasiperiodic, continuous signal – Single cluster of dominant F0 values – F0 and traditional perturbation analysis can be used. Type II – Random or periodic modulations that fluctuate too much to detect a single recurring F0. – Analysis limited to spectral analysis. Type III – Random aperiodic signals with no identifiable fundamental frequency whatsoever. – Not appropriate for most acoustic analysis. SPPA 6400 Voice Disorders: Tasko
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Voice Signal Typing SPPA 6400 Voice Disorders: Tasko Type I Type II Type III
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Fundamental Frequency (F 0 ) Average F 0 speaking fundamental frequency (SFF) Correlate of pitch Infants – ~350-500 Hz Boys & girls (3-10) – ~ 270-300 Hz Young adult females – ~ 200 Hz Young adult males – ~ 120 Hz Older females: F 0 ↓ Older males: F 0 ↑ F 0 variability F 0 varies due to – Syllabic & emphatic stress – Syntactic and semantic factors – Phonetics factors (in some languages) Provides a melody (prosody) Measures – F 0 Standard deviation ~2-4 semitones for normal speakers – F 0 Range maximum F 0 – minimum F 0 within a speaking task
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Intensity Average Intensity Correlate of loudness conversation: ~ 65-80 dB SPL Intensity Variability SPL to mark stress Contributes to prosody Measure – Standard deviation for neutral reading material: ~ 10 dB SPL
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Perturbation Analysis Jitter: variability in the period of each successive cycle of vibration Shimmer: variability in the amplitude of each successive cycle of vibration …
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Synthetic Continuum of Jitter SPPA 6400 Voice Disorders 0.0%2.0% 0.2%2.5% 0.4%3.0% 0.6%4.0% 0.8%5.0% 1.0%6.0% 1.5%
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Harmonic peak Noise ‘floor’ Frequency Amplitude Harmonic peak Harmonics-to-noise Ratio
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Cepstral Based Measures
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SPPA 6400 Voice Disorders Other acoustic measures Maximum Phonational Frequency Range – Highest F0 - Lowest F0 Dynamic range – Highest intensity – lowest intensity Voice Range Profile/Phonetogram – Dynamic range from lowest to highest F0
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Voice Range Profile SPPA 6400 Voice Disorders: Tasko
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Aerodynamic Analysis of Voice SPPA 6400 Voice Disorders: Tasko
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Aerodynamic Testing SPPA 6400 Voice Disorders: Tasko
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Aerodynamic Testing SPPA 6400 Voice Disorders: Tasko
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Aerodynamic Testing Average Flow Rate Typical values 100-200 ml/sec Hyperfunction associated with lower values Hypofunction associated with higher values Subglottal Pressure Typical values 5-8 cm H20 Phonation Threshold Pressure (PTP) Minimum pressure needed to initiate phonation Typical values 3-5 cm H20 Laryngeal Airway Resistance (LAR) subglottal pressure/mean flow rate Estimates the resistance at level of the larynx SPPA 6400 Voice Disorders: Tasko
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Laryngeal Imaging SPPA 6400 Voice Disorders: Tasko
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SPPA 6400 Voice Disorders Laryngeal Imaging Direct Laryngoscopy Indirect Laryngoscopy – Mirror examination – Rigid laryngeal endoscopy Constant light Stroboscopy – Flexible fiberoptic laryngeal endoscopy Constant light Stroboscopy
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SPPA 6400 Voice Disorders Components Endoscope (rigid or flexible) Light source (constant or strobe) Camera Recording device (VHS, computer) If strobe light is used, a neck mounted microphone (or electroglottograph) is used for tracking F o
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SPPA 6400 Voice Disorders Constant light vs. strobe light Constant light source allows viewing of basic structure and function – Identify lesions – Identify abnormalities in ab/adduction – Identify supraglottic activity Strobe light source allows a view of “simulated” vibration – allows assessment of the vibratory function of the vocal folds – May reveal structural abnormalities not seen during constant light endoscopy
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SPPA 6400 Voice Disorders Typical VLS Examination A task list Normal, loud and soft phonation Pitch glide (glissando) Laryngeal diadochokinesis - /i i i/ /hi hi hi/ Cough Normal & deep breathing
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Gross Observations Glottic Closure Supraglottic hyperfunction Mucus General Appearance Mobility SPPA 6400 Voice Disorders: Tasko
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SPPA 6400 Voice Disorders Stroboscopic observations Glottic Closure Phase Closure Symmetry Amplitude Mucosal wave Stiffness/nonvibrating portion/adynamic segment Periodicity
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SPPA 6400 Voice Disorders Example of a VLS evaluation form
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