By the mid-’50s, ideas of social change were starting to grip the U.S., and with the emergence of genres like soul and R&B, music was quick to follow. A new strain of jazz emerged, characterised by the frenzied improvisation of saxophonists like John Coltrane and Sonny Rollins, the rhythmic genius of pianist Horace Silver, and the calculated, swingin’ elegance of trumpeter Miles Davis. Hard bop, New York City’s caustic response to the West Coast’s cool, laidback jazz, pushed forward toward modal jazz, free jazz, and the new frontier of the ‘60s.