Tracy Robertson and Jeff Smith are best known for their roles as the bass and vocal percussionist for world-renowned a cappella group 'm-pact'. Whether laying down straight-ahead funk grooves or crafting complex poly-rhythmic patterns, this powerhouse duo have developed what many consider to be one of the tightest and "grooviest" rhythm sections in the a cappella world. This has been achieved, in large part, through many repetitions and through trial and error. However, they have also spent a great deal of time studying and learning from the great instrumental rhythm section players in funk, jazz, and R&B, as well as world rhythms from Africa, the Caribbean, and Central/South America.