I found a little app for iPhone (KeyFinder - free) that scans the music being played in the room and then shows in real time which key is being played. I like to kind of “play along” the songs I’m listening to, but by the time I sort of guess the key being played, well, the song is over!
So this little app is very useful to find the key right away. I have tested it with a bunch of classical music pieces and it seems accurate (classical music records/CD’s always shows the key being played (Sonata in Gb Minor, for exemple).
Once I see which key is being played I quickly run the scale on the bass to find the 3rd and the 5th. I then “improvise” on that triad.
My question is this; I see on the app the chord progressions in the first bars and then it only shows one key. I guess that key is called the dominant? So, can I keep on doing the triads in that dominant key for the whole song, even though I can hear the different progressions?
Perhaps @JoshFossgreen can enlighten me?
Also, does anybody use that kind of app, and if so, which one?