Even in seemingly simple music, playing with a rhythmically tight, in tune, in “tone” and expressively perceptive group gives you the opportunity to exercise so many physical and mental muscles and stimulate your emotive and pleasure centers.
The obvious joy of rhythmic synchronicity is probably the easiest for a layperson to grasp. Harder to describe is the feeling when horn players really listen and react to each other, changing timbre, volume and color of tone in such a unified manner that it almost sounds like one giant horn singing with it’s fat voice.
As a saxophone player, one has to learn to change your sounds in ways that you might not in a solo horn setting. Many of these changes must become somewhat involuntary as you must listen and react very quickly.
I will list some examples although such a list could be endless if other musicians chimed in.
If you are playing a more trumpet-ish, lighting-clap-type phrase, especially with quickly moving melody line you would change your sax sound to a tighter, less complex sound with fewer overtones and really let the trumpetness of the line speak.
Lower register parts are often warm, tromboney sounding sustained chords where you might want a rich or hollow sound, depending on expressive elements. Also, low brass-type jabs are common where you’d want a big fat tone, but with a very focused and strong attack.
It can be especially exhilarating when a saxophone lead comes around and you can sing out with your original sax-voice that you have worked so hard to develop and allow all the fuzzy, overtone-laden characteristics of your sound burst forth.
When I was younger, I used to believe improvising to be the most challenging brain exercise I engaged in musically but as I’ve learned to be a better horn-section player over the years and really thought about and developed the possible nuances, I have found the challenges and rewards to be close to equal.