Sonic Tools Spectrum analyzer for your phone - how to use, basics

Spectrum Analyzer apps

How To Mix With a Spectrum Analyser - SPAN Tutorial

Spectra Lab Android Spectroscopy App

Get a Better View of Your Mix! | These Free Spectral Analyzer Plugins are Essential!

#413 Your PC Soundcard is an Oscilloscope, a Signal Generator, and a Spectrum Analyzer (Arta, REW)

Using a Spectrum Analyzer for Audio Work - BG082

Signal Analyser. The Best Apps for Cassette Tape Decks