Spek (IPA: /spɛk/, 'bacon' in Dutch) helps to analyse your audio files by showing their spectrogram. Spek is free software available for Unix, Windows and Mac OS X.

Features
- Supports all popular lossy and lossless audio file formats thanks to the FFmpeg libraries.
- Ultra-fast signal processing, uses multiple threads to further speed up the analysis.
- High number of frequency bands for the best spectrogram quality.
- Shows the codec name and the audio signal parameters.
- Allows to save the spectrogram as an image file.
- Drag-and-drop support; associates with common audio file formats.
- Auto-fitting time, frequency and spectral density rulers.
- Available in Dutch, English, French, German, Polish, Russian, Spanish, Swedish and Ukrainian.

Spek requires OS X 10.5 or 10.6 and an Intel-based Mac.