In "East St. Louis Toodle-oo" by Duke Ellington, how does the featured musician produce a distinct sound after the introduction?

In "East St. Louis Toodle-oo," the distinct sound created after the introduction primarily comes from the use of mutes on a trumpet. Mutes are devices that modify the sound of brass instruments and can create a range of tonal effects, from softening the sound to adding a unique character. In this piece, the featured musician, who is playing the trumpet, employs different types of mutes to achieve a distinctive timbre that contributes to the overall atmosphere of the composition. This technique is synonymous with the jazz style of the era, where innovative sound production techniques were essential for crafting an engaging musical experience.

The other methods listed do not accurately reflect the practices employed in this particular performance. For instance, playing the trumpet mouthpiece alone would not produce the full sound characteristic of a trumpet; similarly, using a mute with a trombone or singing into a trumpet represents different techniques that are not indicative of the sound heard in "East St. Louis Toodle-oo," specifically associated with trumpet performance and the creative use of mutes.