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Vertical axis: 20 Hz (bottom) to half the sample rate (top), logarithmic. Bright = loud. Nothing is uploaded – analysis happens in your browser.
How to read a spectrogram
Time runs from left to right, frequency from bottom (low) to top (high), and brightness shows loudness. A whistle draws a thin line; a voice draws a stack of parallel lines (harmonics); noise such as rain or wind fills a broad band.
Birders use spectrograms to identify species, sound engineers to find unwanted resonances, and scientists to study everything from bat calls to earthquakes.
Frequently asked questions
Is my audio uploaded?
No. Both the microphone and file analysis run locally in your browser.
What is the difference between a spectrum and a spectrogram?
A spectrum shows frequencies at one moment; a spectrogram stacks many spectra over time so you can see how sound changes.