VibratoScope Web
VS

Results

Audio stays in this browser
⌁VibratoNot analyzed
〰Mean F0--
♫Measured note--
⊙Mean rate--
⌁Mean half-extent--
◎Core FM-Web--
∿CV rate--
∿CV extent--
⟳Complete-cycle windows--
◇Reliability--
Record or load audio to generate results.
Vibrato shape
Upper excursion--
Lower excursion--
Amplitude asymmetry--
Duration asymmetry--
Contour skewness--
Cycle mean absolute deviation--

Positive amplitude asymmetry means a larger upper excursion. Positive duration asymmetry means a longer ascent. These describe shape, not vocal quality.

Waveform

Detected/selected vibrato region is highlighted.

F0 and detected vibrato
Manual ROI

ROI: automatic vibrato region. Drag across the F0 plot to select a stable manual ROI.

For singing passages, drag across the most stable part of the vibrato if the automatic region includes onset, offset, or non-vibrato material.

Instructions

Quick start
  1. Enable the microphone and allow browser access, or load an audio file.
  2. Choose a voice range and task, then record or load the vocal sample.
  3. Use Play to listen to the recording or loaded file.
  4. Check the highlighted vibrato region. Drag across the F0 plot to define or replace a manual ROI.
  5. Expand the F0 display to zoom horizontally and vertically, choose F0 processing, and select a stable ROI.
  6. Export the analysis as a PNG image, CSV table, or JSON summary.

Rate counts complete repetitions. Half-extent is half the peak-to-trough range; it does not imply equal excursions above and below the local center.

Upper and lower excursions use a cycle-specific center after removing linear drift. The cycle absolute deviation is a supplementary measure and differs from an undetrended whole-recording deviation.

Cycle windows overlap by half a cycle. Their count is not a count of independent observations.

For better F0 tracking, prefer an external microphone or audio interface. Webcam microphones may filter low notes.

About VibratoScope

VibratoScope is a browser-based tool for visualizing and estimating F0 and vocal vibrato from recorded or loaded audio.

Developed by Dr. Tiago Lima Bicalho Cruz, FonoTech Academy. Inspired by the VibratoScope desktop application.

Privacy Audio is processed locally in your browser and is not uploaded to a server.

Scope Results support learning and research. They are estimates and should be interpreted with the recording quality and analysis settings in mind. Core FM-Web is a browser-specific regularity index and is not numerically interchangeable with desktop Core FM.

The free desktop software is available at Fonotech Academy.

Core FM-Web (Core Frequency Modulation)

Pedagogic explanation

Core FM-Web describes the regularity of the measured F0 modulation. It is not a judgment of vocal quality, beauty, or technique.

The scale uses a perfectly repeating modulation as its upper reference. Fixed asymmetry can be regular. Changes between cycles lower the score. This is a modulation regularity index, not a measure of vocal-fold jitter.

  • 80–100: high frequency-modulation regularity;
  • 65–79: moderate-to-high regularity;
  • 50–64: variable but partially organized;
  • < 50: low regularity or unreliable tracking.

F0 and detected vibrato

ROI: automatic vibrato region. Drag across the F0 plot to select a stable manual ROI.