Figure 1.
A: Cartilagenous framework measurements of the arytenoid (‘a’) and the thyroid (‘t’) cartilage. B: Horizontal section through larynx at the level of the vocal folds as reconstructed virtually from framework measurements.
Figure 2.
3-D FE model of the vocal folds.
A: Isolated vocal folds. B: Frontal section through the thyroid cartilage and the vibrating portion of the vocal folds shown in Figure 1, perpendicular to the fibers. The triangular element mesh was 12×14 elements for each of 5 layers along the fibers, or along the vocal fold length. Mucosa, ligament, and TA muscle are shown in color for the left vocal fold. The small inset about the larynx is the same top view of the vocal folds as in figure 1 indicating the cross section level with a dotted line.
Table 1.
Input parameters used in model.
Figure 3.
Stress-strain curves for vocal fold tissue.
A: Stress-strain curves vocal ligament and mucosa. B: active and passive muscle tissue (TA, thyroarytenoid muscle; CT, cricothyroid muscle).
Figure 4.
The cross sectional areas of the vocal tract are indicated relative to the location of the glottis (space between vocal folds). The vocal folds inside the dotted square were made of an element mesh as indicated in Figure 2.
Figure 5.
Iso-fundamental frequency contours for self-sustained vocal fold oscillation (solid lines, frequencies in Hertz, Hz) based on 175 simulations (Figure S2). They indicate where vocal fold oscillation can be maintained at a constant fundamental frequency near phonation threshold pressure, which is indicated in kPa on the right and top axis of the MAP. Iso-strain curves (dashed lines, strain ε) indicate the elongation of the vocal fold in order to achieve a certain tension of the oscillating tissue.
Figure 6.
Oscillograms (upper panels) and spectrograms (lower panels) of a red deer call (A), an elk call (B) and three sound simulations (C, D, E). Fundamental frequency of simulations is 60 Hz (in C), 900 Hz (in D) and 1500 Hz (in E). All simulations last 2 seconds. Note that intrinsic noise of the nonlinear system indicates the presence of resonance frequencies even if F0 is above those resonances. Arrows indicate resonance frequencies, which are identical in all three simulations, but they are best visible when the source signal has a low fundamental frequency.
Figure 7.
Efficiency measures across the phonation range of an elk/red deer larynx.
Six main parameters explaining the energy transfer at the laryngeal sound source and as they change with applied lung pressure. A: Peak glottal area, B: peak glottal airflow, C: aerodynamic glottal power, D: radiated sound intensity level. E: Radiated Power, F: Glottal efficiency.
Figure 8.
Results of taking a path through the MAP.
Taking a path through the MAP of Figure 5 along an imaginary line at aTA = 0.4 (indicated by a dotted line in the inset in A), incrementing aCT in steps of 0.05 from bottom to top leads to characteristic changes of acoustic parameters. A: fundamental frequency versus aCT, B: phonation threshold pressure versus aCT, C: phonation threshold pressure versus fundamental frequency, D: ligament stress plotted against strain.