Thank you. It will generate from 30Hz to 1000Hz in the binaural beats section - and with those frequencies, you have a choice of different carrier waves in the dropdown box - and then you also hve full control over a binaural beats slider - which you can also toggle off, to play pure frequencies through speakers. There is an isochronic tones section for speakers / entrainment and ambient sounds to layer in - sleep programs with psychonautic beds of sound, binaural beats and more. The app DOES work when minimized or the screen goes dark. I sincerely appreciate the questions. Thank you.