Complex sentence: Many people asked Nanton how he acquired and formulated his unique style and sounds--in 1921, Nanton heard Johnny Dunn playing the trumpet with a plunger, which Nanton realized could be used to similar effect on the trombone.
Split into simpler sentences: Many people asked Nanton how he acquired and formulated his unique style and sounds. In 1921, Nanton heard Johnny Dunn playing the trumpet with a plunger, which Nanton realized could be used to similar effect on the trombone.