What is a spectrum analyzer?
It shows which pitches a sound is made of: deep bass on the left, high sounds on the right, and the taller the shape, the louder that pitch. It helps you find where a hum, a whine or a hiss sits.
How to use it
- Choose the input. Microphone, an audio file, or the sound of another tab (in some desktop browsers, such as Chrome and Edge).
- Press Start. Allow the microphone if asked. The picture starts moving straight away.
- Pick a view. Spectrum, Spectrogram, Both or Octave bands, in the tabs at the top.
- Point at the picture. Move over it, or drag on a phone, to read the pitch and level at that spot.
What everything means
- Views. Four ways to look at the same sound.
- Input and Start. Where the sound comes from, and the button that starts and stops it.
- The picture. A tall thin spike is one steady tone, like a hum. A wide hill is noise, like air or traffic. Green is quiet; amber and red are loud.
- Tools. Peak hold keeps the highest line. Freeze stops the picture. Save reference keeps a line to compare against. Export saves a picture or the numbers.
- Readouts. The loudest pitch and its musical note when one clear tone stands out, the peak, the average and the crest (how spiky the sound is).
- Bass, mids and treble. How much of the sound is low, middle and high.
The four views
Spectrum is the sound right now. Spectrogram adds time: it scrolls, and colour shows loudness, so you can see a sound come and go. Both shows the two together on one frequency scale. Octave bands group the pitches into wide bars, the way acoustic reports do.
Compare before and after
Press Save reference to keep the current shape as a coloured line. Change something — move a speaker, close a window — and the difference is right there. You can keep two at a time.
Why does it need my microphone?
Only to hear the sound you want to look at. Everything is worked out inside the page; nothing is recorded or uploaded. A file you open stays on your device too.
What is a spectrogram?
A picture of the spectrum over time. Time runs sideways, pitch runs up, and colour shows how loud each moment was.
Why are the numbers negative?
They count down from the loudest sound the input can take, which is 0. Everything real sits below it.
Can I analyse a song or a video?
Yes. Set the input to Audio file, or to Tab or system audio in a desktop browser that offers it, such as Chrome or Edge — tick “Share tab audio” when asked.
What is the note under the loudest frequency?
The nearest musical note, and how far off it is in cents. It only shows when one clear, steady tone stands out. Handy for tuning or for naming a hum.