Left inferior frontal gyrus responsible for language production and motor planning of speech. Coordinates articulatory sequences for fluent speech. ORAVYS detects micro-variations in prosody, hesitation patterns, and phonemic transitions that reveal vocal authenticity, fluency, and fatigue patterns.
Direct control of 100+ orofacial, lingual, and laryngeal muscles. The somatotopic map has an enlarged representation for the orofacial region (homunculus). Motor execution disturbances create measurable articulatory imprecision.
Posterior superior temporal gyrus | comprehension of spoken language. Connected to Broca's area via the arcuate fasciculus. Disruption affects speech coherence and verbal fluency.
Emotional processing center. Limbic activation propagates through the neural pathway to laryngeal muscles, creating involuntary acoustic variations that distinguish genuine human speech from synthetic output.
Analysis of tempo variations, vocal intensity envelopes, phonemic transitions, hesitation patterns, and pauses. These acoustic signatures reveal genuine speech characteristics, vocal authenticity, and speaker state.
Transmits nerve signals from brain to respiratory and postural muscles. Spinal nerves (C1-C7, T1-T12) innervate the diaphragm and intercostal muscles essential for breathing and phonation support.
7 cervical (C1-C7), 12 thoracic (T1-T12), 5 lumbar (L1-L5) vertebrae with natural lordotic and kyphotic curves. Spinal posture directly influences lung capacity and vocal projection. Slouched posture reduces thoracic volume by up to 30%.
Innervates the diaphragm from cervical vertebrae. Essential for respiratory control. Any cervical compression or tension affects vocal respiratory support and creates detectable breath irregularities.
Variations in vocal volume stability, pitch consistency, and respiratory efficiency reveal postural state, spinal muscle tension, and physical fatigue patterns.
The largest laryngeal cartilage | two laminae fused at an angle (90° in males, 120° in females). Houses and protects the vocal folds. Palpable externally, it anchors the extrinsic laryngeal muscles that control vertical laryngeal position.
Complete signet-ring cartilage below the thyroid. Provides the foundation for the arytenoid cartilages. The cricothyroid joint is the primary mechanism for pitch control -- tilting increases vocal fold tension and raises the fundamental frequency.
Two pyramidal cartilages seated on the posterior cricoid. Their rotation and sliding motions control vocal fold adduction (closing) and abduction (opening). The vocal process of each arytenoid anchors the posterior end of each vocal fold.
Layered structure: epithelium → superficial lamina propria (Reinke's space) → vocal ligament → thyroarytenoid muscle. Vibrate at 85-180 Hz (male) and 165-255 Hz (female). The mucosal wave (Bernoulli effect) | a traveling ripple across the fold surface | is the primary mechanism of voice production. This biological oscillation produces characteristic cycle-to-cycle irregularities that synthetic vocoders cannot authentically replicate.
1. Cricothyroid: Lengthens/tenses folds → raises pitch. 2. Thyroarytenoid: Shortens/thickens folds → lowers pitch. 3. Posterior Cricoarytenoid (PCA): Only abductor | opens glottis for breathing. 4. Lateral Cricoarytenoid (LCA): Adducts folds for phonation. 5. Interarytenoid: Closes posterior glottal gap.
Autonomic activation propagates through the superior laryngeal nerve (branch of vagus CN X) to the cricothyroid muscle. This creates involuntary pitch and wave regularity changes -- a biological response absent in synthetic speech. ORAVYS measures these acoustic deviations across multiple dimensions.
The epiglottis (leaf-shaped elastic cartilage) deflects food away from the airway during swallowing. The hyoid bone (U-shaped, only bone not articulating with another bone) is the superior anchor of the laryngeal framework. Hyoid position affects pharyngeal resonance and vocal timbre.
Total volume 4-6 liters in adults. Vital capacity (forced expiration) determines maximum phonation duration. ORAVYS measures inspiration/expiration ratios and airflow stability across the full phonation cycle.
Main muscle of inspiration (75% of respiratory work). Contraction lowers the diaphragm dome, creating negative intrathoracic pressure that draws air in. Expert diaphragmatic control (trained singers) ensures constant subglottic pressure for fluid speech.
5-10 cmH₂O for normal speech. 15-30 cmH₂O for singing or vocal projection. Unstable pressure manifests as a trembling or fatigued voice -- directly measurable as increased amplitude instability.
Analysis of respiratory pauses, breath-related vocal tremors (flow 100-200 ml/s), intensity envelopes, and volume stability. Reveals pulmonary state, anxiety levels, and physical exertion.
60-100 bpm at rest, rises to 120+ under acute stress. Cardiac pulsations create detectable low-frequency oscillations in the vocal signal at 4-8 Hz. ORAVYS extracts heart rate variability (HRV) signatures from voice alone.
The vagus nerve (CN X) is the primary parasympathetic pathway to the heart. High vagal tone = calm, regulated heart rate. Low vagal tone = stress, anxiety, sympathetic dominance. Voice prosody reflects vagal tone through pitch variability patterns.
Common → Internal/External carotid arteries irrigate the larynx, pharynx, and facial structures. Blood flow influences vocal performance. Reduced irrigation = accelerated vocal fatigue and breathiness.
Acoustic patterns at cardiac-coupled frequencies, cardio-respiratory coupling analysis, and rhythmic variability in the vocal signal. These distinguish genuine human speech from synthesis output and reveal speaker state.
Legs provide essential postural stability for effective phonation. A stable standing position allows optimal thoracic expansion and maximal vocal projection power.
The entire skeleton acts as a resonance chamber. Vibrations propagate from vocal folds through the spinal column, ribcage, and limbs. Leg position influences global resonance and perceived vocal timbre.
Postural fatigue and instability manifest as variations in volume stability, pitch consistency, and vocal efficiency. Standing vs sitting creates measurable acoustic differences in resonance structure and spectral tilt.