Spectrogram Analyzer
See sound as a picture: frequencies over time, with tap-to-analyze partials, ratios, and implied fundamentals.
What a spectrogram shows
A spectrogram plots time across the horizontal axis, frequency up the vertical axis, and energy as brightness. A sustained instrument note appears as a stack of bright horizontal lines: the fundamental at the bottom and its harmonic partials stepping up above it. Glissandi curve, vibrato ripples each line, and noisy or percussive sounds smear energy broadly rather than into clean lines. It is the most direct way to see what a sound is actually made of.
What the analyzer does
Import an audio file or record straight from the microphone, and the module computes a short-time Fourier transform and renders it as a zoomable heatmap. You control the analysis and the display:
- FFT size and overlap: trade time resolution against frequency resolution to suit transients or sustained tones.
- Dynamic range and brightness: set how many decibels map across the color ramp, and lighten or darken the display.
- Log or linear frequency: view octaves at equal spacing, or frequency at equal spacing.
- Heatmap or Peaks: draw the full heatmap, or switch to Peaks to render only the loudest partials as continuous trails across frames. Dynamic range and the peak-trail count set how many faint partials the Peaks view keeps.
- Pinch to zoom and drag to pan to inspect a single event closely. Dragging pans in both directions, and the Time and Freq zoom buttons scale each axis independently.
Imports cover wav, mp3, flac, m4a, mp4, aac, ogg, and opus. A take recorded from the microphone can be exported with Save Recording, which writes the take to a WAV file and hands it to the system share sheet, so an analysis session doubles as a way to keep the audio.
Tap to analyze partials
Tap anywhere on the heatmap to drop a crosshair and read the loudest peaks at that instant. Each partial shows its nearest pitch name, exact frequency in Hz, cents deviation, and relative level, and can be auditioned on its own, either as a sustained Continuous tone or as a Staccato note shaped by a Pluck, Marimba, or Pad envelope.
The module also reads the peaks as a harmonic series. Each one is expressed against the lowest peak as a whole harmonic number, with a signed cents deviation from that exact harmonic, so a partial sitting eleven cents flat of the fifth harmonic reads as such rather than being forced into an approximate fraction. Below that it searches for the implied fundamentals whose harmonic series would contain the peaks: the same missing-fundamental reasoning the ear uses. Press play and a white line tracks the audio across the spectrogram as it sounds.
Who this is for
The Spectrogram Analyzer is for anyone who wants to look inside a sound: spectral composers checking the partial content of a sample, orchestrators studying how a chord's overtones stack, sound designers hunting resonances, and students connecting what they hear to what they see. To compute the overtone series from a single fundamental, use Harmonic Series; to explore the combination tones that emerge between several frequencies, use the Spectral Calculator.