Spek is an acoustic spectrum analyser that displays the frequency content of audio recordings as spectrograms. It uses FFmpeg for audio decoding and wxWidgets for its graphical interface.
A spectrogram represents sound across three dimensions: time, frequency and intensity. This makes Spek useful for identifying frequency cutoffs, examining the distribution of acoustic energy and investigating differences between recordings.
The application concentrates on providing a straightforward visual representation of audio files rather than offering audio editing or recording facilities. Its compact interface makes it easy to inspect a recording without loading a complete digital audio workstation.
This is free and open source software.
Key Features
- Generate spectrograms showing how frequency content changes over time.
- Decode a wide range of lossy and lossless audio formats using FFmpeg.
- Display audio codec information and technical signal parameters.
- Select individual audio streams and channels for analysis.
- Adjust the discrete Fourier transform window size.
- Choose different window functions for spectral analysis.
- Configure the upper and lower limits of the displayed dynamic range.
- Switch between multiple spectrogram colour palettes.
- Automatically fit time, frequency and spectral intensity rulers.
- Drag and drop audio files into the application.
- Save generated spectrograms as image files.
- Multithreaded signal processing for analysing audio recordings.
- Keyboard shortcuts for common display and analysis settings.
- Cross-platform support – runs on Linux, macOS, and Windows.
Website: github.com/alexkay/spek
Support:
Developer: Alexander Kojevnikov and contributors
License: GNU General Public License v3.0

Spek is written in C and C++. Learn C with our recommended free books and free tutorials. Learn C++ with our recommended free books and free tutorials.
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Read our verdict in the software roundup.
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