The phrase “rhythm changes” refers to songs that use the same chord changes as Gershwin’s famous Broadway hit “I Got Rhythm.” In a previous article we discussed some tips for approaching this well-known chord progression, including some hints for memorizing the form, adding some chords on the bridge, and doing some chord substitution on the ‘A’ section. In this article, we’ll look at some tips that are specific to rhythm changes improvisation, discussing licks, scales, and some important listening examples that you should check out. Rhythm changes tip #1: Try some tritone substitution on the bridge. The original bridge (shown below in the key of Bb) is a series of dominant chords that resolve down a 5th. Measure 1 of the bridge starts with a D7 chord, which resolves to G7, then C7, then F7, which resolves to the Bb major chord that starts the final ‘A’ section. Rhythm Changes Pt II(1) Using tritone substitutions for any or all of the dominant chords on the bridge can give us a lot of different combinations and options. For example, we can tritone sub all of the chords… Rhythm Changes Pt II(2) …Or some of the chords… Rhythm Changes Pt II(3) Subbing out some of these chords for other chords will result in some new comping options even if the bass player continues to play the original chord. How is that so? Because even if you play a B7 chord (last two bars of the bridge) and the bass player plays an ‘F’ (for the original F7 chord), those two chords still possess a functional relationship. The chord tones of B7 (B, D#, F#, A) will sound as the #11, 7th, b9, and 3rd over the bass player’s ‘F.’ Rhythm changes tip #2: Learn the “lydian dominant” scale and practice improvising with it. The lydian dominant scale is not a naturally-occurring mode, but rather a combination of the lydian and mixolydian modes. Jazz players use this scale a lot to solo over dominant chords, which makes it a very useful scale to know for improvising over the chords of the bridge. The lydian dominant scale combines the #4 of the lydian mode with the b7 of the mixolydian mode. Rhythm Changes Pt II(4) A good practice tip would be to first learn the D, G, C, and F lydian dominant scales and practice playing them over the chords of the bridge. Then, learn the Ab, Db, F#, and B lydian dominant scales, which represent the tritone substitutions of the chords above. Rhythm changes tip #3: Check out some essential listening - and start transcribing some licks! Transcribing scares some students, but it is probably one of the absolute best things you can do to quickly gain confidence, understanding, and material for improvisation. And it’s not difficult, just a little unfamiliar. Start simple and start small. I’m suggesting that you begin by listening to this recording of “Oleo” (a classic rhythm changes tune) featuring Miles Davis and Sonny Rollins (two of the heaviest of jazz heavyweights). Notice how simple Miles Davis keeps his solo. Notice how much space Sonny Rollins leaves between his phrases at the start of his solo. Now, find one little phrase or lick that you like and start by transcribing that. Work in small little phrases and if you feel like you’re ready, try piecing together a whole solo. Then practice playing the solo in time with the recording. Here’s a little lick from Miles Davis to help get you started (found at the 0:40 mark - a nice lick that works over the Bb - G7 - Cm7 - F7, or I-VI-ii-V, chord sequence). Enjoy! Rhythm Changes Pt II(5)    
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