Audio Spectrum Analyzer
Check whether a track is really 320 kbps or truly lossless — the spectrogram is rendered locally in your browser, files never leave your device.
Drag and drop audio files here, or click the button below to add files.
See what a download really contains before you play it
DJs constantly pull tracks from pools, stores, and free download gates, and the label on the file is not always the truth. A 320 kbps MP3 re-encoded from a 128 kbps rip keeps the bitrate tag but loses the top end forever, and a FLAC made from an MP3 is still an MP3 underneath.
A spectrogram makes this visible in seconds: lossy encoders cut the highest frequencies at predictable points, so the cutoff line tells you roughly what the audio has actually been through. This tool draws the full-track spectrogram, finds that cutoff, and compares it with what the file claims to be.
What this spectrum analyzer is built for
A true 320 kbps MP3 keeps energy up to roughly 20.5 kHz. If the spectrum dies at 16 kHz, the file was upconverted from a low-bitrate source.
Real lossless audio extends to the edge of the spectrum. A hard cutoff around 19–20 kHz in a FLAC or WAV usually means a lossy transcode.
Decoding, FFT, and rendering all run in your browser via WebAssembly, so it works with unreleased material and large files without privacy worries.
How to check a file
- Drop the audio file into the analyzer — MP3, FLAC, WAV, AAC, and OGG all work.
- Read the spectrogram: look for a hard horizontal line where the energy stops, and compare it with the cutoff value the tool reports.
- Check the verdict against the declared format and bitrate, and re-download from a better source if the file does not hold up.
Spectrum analyzer FAQ
How can I tell if an MP3 is really 320 kbps?
Look at where the high frequencies stop. A genuine 320 kbps encode keeps content up to about 20.5 kHz, while files upconverted from 128 kbps stop near 16 kHz no matter what the tag says.
Why does my FLAC cut off at 19 kHz?
A hard cutoff below 20 kHz in a lossless file usually means it was converted from a lossy source such as a 256 kbps MP3 or AAC. The container is lossless but the missing frequencies are gone for good.
Is this a replacement for Spek?
It covers the same job in the browser: a full-track spectrogram with a dB color scale plus an automatic cutoff read-out, with no install and no upload — files are analyzed locally on your machine.
Use the audio formats guide to understand lossy versus lossless tradeoffs, the converter when you need a different format, and the BPM changer for tempo prep.