Defining features of the rockabilly sound included strong rhythms, vocal twangs, and common use of the tape echo; but progressive addition of different instruments and vocal harmonies led to its "dilution". Initially popularized by artists such as Wanda Jackson, Billy Adams, Johnny Cash, Bill Haley, Buddy Holly, Elvis Presley, Carl Perkins, Bob Luman, Eddie Cochran, and Jerry Lee Lewis, the rockabilly style waned in the late 1950s; nonetheless, during the late 1970s and early 1980s, rockabilly enjoyed a revival. An interest in the genre endures even in the 21st century, often within musical subcultures. Rockabilly has spawned a variety of sub-styles and influencing other genres such as punk rock.