Spectrogram Viewer
Visualize the frequency content of your audio over time with an interactive spectrogram. Zoom, pan, and customize colors.
What this tool tells you
What it does
Use this when you need to see how frequency content changes over time: transients, harmonics, background noise, edits, sustained tones, and where the bandwidth ends.
How to use it
Open a file, then scroll to zoom in on a passage and drag to pan. Adjust the color range so quiet detail becomes visible, and compare the top of the spectrum against the bandwidth-ceiling marker.
How to interpret it
A worked example: a 44.1 kHz file whose energy ends in a sharp shelf near 16 kHz, with an empty band above, is a pattern often seen with low-bitrate MP3 encoding — but filtering, mastering choices, codec settings, and the source itself can produce the same picture. A spectrogram shows evidence, not proof of a file’s origin.
Frequently Asked Questions
- What is a spectrogram?
- A spectrogram is a visual representation of the frequency spectrum of audio over time. Frequency is shown on the vertical axis, time on the horizontal axis, and color intensity represents amplitude.
- How can I inspect lossy-encoding evidence in a spectrogram?
- A sharp horizontal cutoff can be consistent with lossy encoding, but it is not unique to it. Filtering, mastering choices, codec settings, and the source itself can produce similar patterns.
- How do I read a spectrogram of a music file?
- Worked example: open a song and look at the vertical axis first. Bass and kick drum energy sits low (below ~200 Hz), vocals and most instruments in the middle, cymbals and air near the top. Bright vertical stripes are drum hits; steady horizontal lines are sustained tones or hum. If the picture ends abruptly at a fixed frequency — for example a hard shelf near 16 kHz with nothing above — that pattern is often seen with low-bitrate lossy encoding, though it can also come from filtering or the original recording. Use it as one clue alongside the bandwidth-ceiling marker, not as a verdict.
- Why does my high-resolution file show little energy above 22 kHz?
- Many genuine recordings contain little musical content above 22 kHz, and microphones, mic preamps, and mixing choices often roll off ultrasonic energy. An empty top octave on its own does not show that a file was upsampled; the Hi-Res Audio Verifier combines several signals for a fuller picture.
Selected files are processed locally in the browser and are not uploaded to TrueRes for processing. Open this page in a modern browser to use the interactive tool.