Audio Spectrum Visualizer

Free Audio Visualizer lets you play audio files from your music library, and visualize them in real time using Spectrum Analyzer, Spectrogram, Spectroscope, Oscilloscope and Vectorscope.

You can also change playback speed of the audio on the fly, and change the color palettes used for Spectrum Analyzer and Spectrogram.

The app plays and visualizes audio from the music library, so the audio files need to be physically present on your device, and not DRM protected.

Alternatively, music files can be copied directly into the app's documents folder using iTunes.