Audizr is described as 'Real-time precision audio spectrum analyzer for professionals and sound enthusiasts. Spectrum analysis with Audizr reveals outstanding details in sound captured from a microphone'. There are three alternatives to Audizr for Android, Linux, Mac and Windows. The best alternative is Friture, which is both free and Open Source. Other great apps like Audizr are Spectroid (Free) and Oscilloscope (Free, Open Source).
Real-time audio spectrum analyzer with reasonable frequency resolution across the the entire frequency spectrum. - Spectrum - Waterfall - Max-hold trace - Peak markers - Linear or logarithmic frequency scale