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Music Visualizer Lab
Create a Visualizer

Free audio spectrum generator

The frequency controls, and what each one actually does to the picture.

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Frequency range

Two settings decide which part of the spectrum is analysed at all: lowest frequency and highest frequency, both under Advanced. The range between them is divided into 256 bands, spaced logarithmically so each octave gets equal width.

The defaults are 30 Hz to 16 kHz. Raising the lower bound to around 50 Hz removes rumble and DC content that moves the first band or two without being musically interesting. Lowering the upper bound to 14 or 16 kHz stops you spending screen width on bands that stay near silent.

Separately, the frequency range control inside the style section decides how much of that analysed range gets drawn. At 1 you see all of it. Lower values zoom into the low end. It is the control that most often fixes a spectrum that looks lopsided.

Response

Sensitivity

Overall sensitivity multiplies everything. Bass, mids and treble each have their own multiplier on top, applied to the lower 18 percent, the middle, and the top 40 percent of the band range. If the kick is swamping the picture, pull bass down rather than pushing the others up, then correct the overall level.

Attack and decay

Attack is how quickly a band is allowed to rise, decay is how quickly it falls. They are deliberately separate: fast attack with slow decay is what makes a spectrum feel like it is reacting to music rather than flickering. Both are frame rate independent, so a 30 frame per second export moves the same way as a 60 frame per second preview.

Smoothing

A light blend applied after attack and decay, which takes the edge off band to band noise. High values settle everything down and can make the spectrum feel disconnected from the track if you overdo it.

Starting points

Electronic and dance. Range around 0.7, bass at 1.2, attack high at 0.9, decay around 0.12. Gives hard hits with a visible fall.

Acoustic and vocal. Range 0.85, bass 0.8, smoothing around 0.8, decay 0.2. Calmer, and stops the low mids dominating.

Lo-fi and ambient. Smoothing 0.85, attack 0.4, decay 0.08, normalisation on. Slow and continuous rather than percussive.

Spoken word. Range 0.55, treble 1.3, smoothing 0.75. Or use the three band meter from the spectrum styles instead.

Questions

What does FFT size change?

It trades frequency detail against speed of response. A larger window resolves closer frequencies apart, so the low end separates into distinct bands instead of moving as one lump, but it also averages over a longer slice of time so fast transients look slightly softer. 4096 suits most music. Drop to 1024 or 2048 for percussive material where you want the hits sharp, and raise it if you want detail in the bass.

What is the difference between smoothing and decay?

Decay controls how fast a band falls after a peak, so it shapes the motion. Smoothing blends each band with what it just was and with its neighbours, so it reduces jitter without changing the overall shape much. If the spectrum looks noisy, raise smoothing. If it looks frantic, lower decay.

Should I leave normalisation on?

For most uploads, yes. It scales the spectrum against a running peak so a quiet mix still fills the frame. Turn it off when you want the visualizer to show real dynamics, for example if a track has a deliberately quiet intro that should look quiet.

Why set a maximum frequency below 20 kHz?

Because most tracks have very little up there, and any band you include but that stays empty is width you have given away. Pulling the maximum down to 14 or 16 kHz gives the rest of the spectrum more room without losing anything you can see.

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