Here's another 16 bar solo of "super funk rock" that packs quite a punch. The melody is simple and funky, and the solo is concise and electrifying. While the harmony stays within the Bb minor pentatonic scale, Shorty keeps it interesting by using texture, rhythm, and phrasing.
The obvious effect on this studio version is the use of the electronic "wah" filter. This effect can be produced either manually with a foot pedal, or automatically with an Auto-Wah effect unit. It appears that the latter was used on this recording because the wah effect is clearly present on the sixteenth note rhythms. The dynamics and staccato technique are what control the rate of automatic wah. The manual wah effect is controlled by the angle position of a foot pedal, which is used to shape the sound. While I've seen a wah pedal used effectively in a live performance, I would imagine that it would be difficult for anyone's foot to be active enough to keep up with Shorty's playing on this solo.
Trombone Shorty's music is full of lively rhythms. Syncopation is always present in New Orleans music, and within the first four bars of the solo, Shorty accents the off-beat and shifts back to the downbeat. Bars 5-8 show off his natural swing, and also explores the pentatonic through the use of a rhythmic motive. And to top it all off, he busts out the double-tounging for an extended length, and rhythmically resolves up to a solid tonic note. I assume that those Eb's and F's are played in third and forth position, respectively, for the sake of speed.
Although there's plenty of little things within this solo, it's important to look at the shape of the entire solo. It's basically comprised of four phrases of four bars. To further analyze these phrases, the "target"in the first two bars appears to be F, the dominate, around which you can work in and out of the key, eventually resolving down to the Bb tonic in the last two bars. A good sense of cadential melody is required in order to shape a solo into logical statements and phrases.
Going back to the topic of Wah Trombone, here's a YouTube video [expired] of Mark Mullins, of the New Orleans band, Bonerama, performing a solo to Jimi Hendrix's "Crosstown Traffic." He's using a manually controlled wah foot pedal, along with polyphonics, to produce that rock trombone sound.
Recommended reading: Total Trombone: 13 Etudes by Michael Davis. Published by Hip-Bone Music.