SpectrumViz shows your Mac's audio as columns of LEDs, in the style of the spectrum display on an 80s hi-fi amplifier. It runs from the menu bar, without a Dock icon. The display is a small window you can park in a corner of the screen and keep above your other windows, or run full screen. There are four LED color schemes, 80s Hi-Fi, Plasma Red, Amber and Rainbow, 16 to 32 frequency bands, and a stereo or mono layout. A peak indicator and frequency labels can be switched on or off. SpectrumViz only needs permission to record system audio, not the screen. The audio is processed on your Mac and never leaves it, and the app collects no data. macOS asks for that permission the first time you open the display. If you declined it, you can turn it on later in System Settings.