Voice Stability Test app for iPhone and iPad

This test can check your voice quality by variations of frequency (Jitter).

Jitter and shimmer are measures of the cycle-to-cycle variations of frequency and amplitude, respectively, which have been largely used for the description of pathological voice quality.

Higher jitter levels suggest that something is interfering with normal vocal fold vibration and the mucosal wave.

Whereas jitter is a measure of the percentage irregularity in the pitch of the vocal note, shimmer is a measure of the percentage irregularity in the amplitude of the vocal note.