Use the Mac version, now portable! In my R&D of tinnitus modelling, the Mac version is great. Now I have it on my Android phone for demonstrations on the go! And for my youngest daughter who is noisy, kind of levels the playing field then :)
Cumbersome The interface isn't particularly intuitive, which is my primary gripe with this app. If I want to only play one or two tones out of three I've programmed, I have to delete the ones I don't want to use, rather than simply mute them, and then reprogram them to bring them back again. On exiting, I was redirected to a website; it might have been benign, but I still object to that redirect. It has advantages over similar apps, such as accepting decimal values entered for Hz.
Only Landscape :-( Would have given 5 stars but only allows landscape mode on Galaxy S5. Other than that, works great.
Missing one thing All it needs is a timer for each frequency.
ToneGen Free multiple tone generator
Apparently for a large tablet.
Frequency Sound Generator - waveform audio signal generator/ function generator
Audio Tone Generator 20 - 20 000 Hz. Perfect for testing or pranking!