Calculate jitter, shimmer, and recording quality metrics with clinical interpretation

Quality assessment: "Good" (-25 to -10 dBFS), "Suboptimal" (-30 to -25 or -10 to -6 dBFS), "Poor" (<-30 or >-6 dBFS). Example: "Good"

Detailed warning message if quality is suboptimal or poor. Empty string if good. Example: "CAUTION: Recording level is low (<-25 dBFS). Consider re-recording with slightly higher volume for more reliable results."

Mean recording intensity in dBFS (decibels relative to full scale). Target range: -25 to -10 dBFS. Example: -18.3

Root-mean-square amplitude (0-1 scale). Used to calculate dBFS. Example: 0.122

Local jitter (period-to-period variation) in percent. Primary jitter measure. MDVP reference: 1.04% (not validated for Praat). Example: 0.85

5-period perturbation quotient in percent. Smoothed jitter over 5 periods. Example: 0.78

Relative average perturbation in percent. Average over 3 consecutive periods. Example: 0.82

Difference of differences of periods in percent. Sensitive to small perturbations. Example: 1.23

Local shimmer (peak-to-peak amplitude variation) in percent. Primary shimmer measure. MDVP reference: 3.81% (not validated for Praat). Example: 2.45

Local shimmer in decibels. Logarithmic amplitude perturbation. Example: 0.215

3-period amplitude perturbation quotient in percent. Short-term shimmer. Example: 2.31

5-period amplitude perturbation quotient in percent. Medium-term shimmer. Example: 2.38

11-period amplitude perturbation quotient in percent. Long-term shimmer trends. Example: 2.52

Difference of differences of amplitudes in percent. Sensitive to amplitude changes. Example: 3.47

Mean fundamental frequency in Hz. Averaged across voiced segments. Example: 185.7

Standard deviation of F0 in Hz. Pitch variability indicator. Example: 7.2

Coefficient of variation of F0 in percent. (F0_STD / MEAN_F0) × 100. Pitch stability metric. Example: 3.88

Percentage of voiceless (unvoiced) frames. Indicates phonation breaks. Example: 5.2

Number of vocal fold vibration periods analyzed. Minimum 20 required, 100+ optimal. Example: 245

Flag indicating insufficient periods: 1 if <100 periods (reduced reliability), 0 if ≥100 periods. Example: 0

Flag against the MDVP reference (not validated for Praat): "Normal" (≤1.04%) or "Elevated" (>1.04%). Example: "Normal"

Flag against the MDVP reference (not validated for Praat): "Normal" (≤3.81%) or "Elevated" (>3.81%). Example: "Normal"

Interpretation text for jitter results. Example: "At or below MDVP reference (1.04 %), not validated for Praat"

Interpretation text for shimmer results. Example: "At or below MDVP reference (3.81 %), not validated for Praat"