Every voice score is built from a handful of acoustic metrics. Here is a plain-English guide to what each one measures in acoustic voice analysis.
Jitter
Jitter measures tiny variations in the length of each vocal-fold vibration cycle (frequency perturbation). Healthy connected speech is usually under ~1%. High jitter can indicate instability or strain.
Shimmer
Shimmer measures variation in loudness from cycle to cycle (amplitude perturbation). Healthy values are typically under ~3.5%. Elevated shimmer is associated with roughness and breathiness.
HNR (Harmonics-to-Noise Ratio)
HNR compares the harmonic (musical) energy of your voice to noise. Higher is better — healthy connected speech often sits around 10–20 dB. Low HNR suggests a breathy or noisy voice.
CPPS (Cepstral Peak Prominence, Smoothed)
CPPS is one of the most reliable single indicators of voice quality, especially for breathiness and dysphonia. Higher CPPS = clearer, more periodic voice.
AVQI (Acoustic Voice Quality Index)
AVQI combines several measures into one overall severity index. Lower AVQI means better voice quality.
How these become your voice score
Each metric is mapped onto a 0–100 scale using clinically informed thresholds, then combined into higher-level scores like voice health, vocal fatigue, and hoarseness. Learn more in What Is a Voice Analysis Tool.