What is vocal jitter?
Jitter measures cycle-to-cycle variation in the pitch period of a voice — what it indicates, what counts as normal, and why it appears in a singing report.
The measurement
When you sustain a note, your vocal folds open and close in a repeating cycle a few hundred times a second. Jitter is how much the length of that cycle varies from one repetition to the next, expressed as a percentage of the average cycle length.
A perfectly periodic tone — a synthesiser — has zero jitter. A human voice never does, and a small amount is what makes a real voice sound like a person rather than an oscillator.
What counts as high
Local jitter above about 1% is the figure most often cited in the voice literature as the boundary of the normal range for a sustained vowel, and it is used clinically as one screening indicator among several.
sentivoice opens a vocal strain problem above 1.5% local jitter, and treats 5% as maximally severe. The threshold sits above the clinical figure deliberately: this is a singing report and a singer is not a patient, so the number that triggers practice should be one that means something has actually gone wrong in the take.
What moves it
Fatigue, dehydration, illness, pushing for volume, and singing above your comfortable range all raise jitter, usually within one session. That volatility is not noise in the measurement — it is the measurement working. Jitter describes the state of your voice on the day, which is exactly why it is worth tracking across takes rather than reading once.
How it is computed here
From the isolated vocal track using Praat, the standard acoustic phonetics toolkit, over the voiced segments of the recording. It is a direct measurement of the audio, not a model estimate — the same class of number a voice clinic would take, computed by the same software.
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Run a 30-second quick checkCommon questions
Is high jitter a sign of vocal damage?
It is an indicator, not a diagnosis. Elevated jitter is associated with a wide range of conditions and also with being tired, dry, or ill on the day. Persistent hoarseness, pain or lost range are reasons to see an ENT specialist or speech-language pathologist.
What is the difference between jitter and shimmer?
Jitter is variation in the timing of the cycles — the pitch period. Shimmer is variation in their amplitude — the loudness. They usually move together but they measure different things, and both feed the vocal strain score.