Table 2.
SDs averaged across subjects and phonetic conditions for kinematic variables (jaw orientation and horizontal jaw position) and acoustical variables (F1 and F2 frequencies)
| Variable | Upright | Overall | Ratio | |
|---|---|---|---|---|
| Kinematic (consonant) | Jaw orientation | 0.286 | 0.660 | 2.31 |
| Horizontal position | 0.217 | 0.681 | 3.14 | |
| Kinematic (vowel) | Jaw orientation | 0.515 | 0.999 | 1.94 |
| Horizontal position | 0.207 | 0.712 | 3.44 | |
| Acoustic | F1 | 21.00 | 41.36 | 1.97 |
| F2 | 29.00 | 57.48 | 1.98 |
Jaw orientation is given in degrees; horizontal position is given in millimeters, and acoustical frequency is given in hertz. Values are shown for the upright condition alone (upright column) and across all three gravitational conditions (overall column). In every case, the ratio of SD across orientations to SD in the upright condition (ratio column) shows that variation attributable to changes in head orientation is substantially greater than the variation under normal speaking conditions.