Spek (IPA: /spÃ??k/, '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.
It supports popular lossless audio files formats, uses multiple threads for faster analytics, ultra-fast signal processing, and a high number of frequency bands for the best spectrogram quality. Spectrograms can be saved as images, with drag and drop support.