What is harmonics-to-noise ratio (HNR)?
HNR is how much of your voice is periodic tone versus turbulent noise, in decibels — the clearest single number for how clean a take is.
The measurement
A voiced sound is part periodic — the repeating buzz of the vocal folds — and part aperiodic noise, mostly air escaping through folds that are not fully closing. Harmonics-to-noise ratio is the balance between the two, in decibels.
A high HNR means most of the energy is periodic: a clear, ringing tone. A low HNR means a large share of the sound is turbulence: breathy, hoarse or rough.
What counts as low
Values above roughly 20 dB are typical of a clean sustained vowel from a healthy voice. sentivoice opens a vocal strain problem below 15 dB and treats 5 dB as maximally severe.
One caveat worth stating plainly: HNR is measured on the isolated vocal, and pulling a voice out of a dense mix leaves artefacts behind that depress the number. A take with a loud backing track will tend to read lower than the same voice recorded alone — so the most comparable readings come from recording the same way each time, which is what an unaccompanied 30-second check gives you.
What moves it
Anything that stops the vocal folds closing completely: fatigue, swelling from illness, dehydration, and habitual breathy phonation. Ambient noise in the room also lowers it, since noise in the recording is noise in the measurement. Recording somewhere quiet is worth more to this number than any technique change.
Run a 30-second quick check
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Run a 30-second quick checkCommon questions
Is HNR the same as signal-to-noise ratio?
No. Signal-to-noise ratio compares a recording against the noise floor of the room and the equipment. HNR compares the periodic and aperiodic components within the voice itself. A pristine studio recording of a hoarse voice has excellent SNR and poor HNR.
Why did my HNR drop when nothing else changed?
Check the room and the microphone before you check your technique. Background noise, a different mic distance, and vocal separation from a busier mix all move this number without your voice having changed at all.