Grunge is generally characterized by a sludgy guitar sound that uses a high level of distortion, fuzz and feddback effects. Grunge fuses elements of hardcore punk and heavy metal, although some bands performed with more emphasis on one or the other. The music shares with punk a raw sound and similar lyrical concerns. However, it also involves much slower tempos, disonant harmonies, and more complex instrumentation – which is reminiscent of heavy metal. Some individuals associated with the development of grunge, including Sub Pop producer Jack Endino and the Melvins, explained grunge's incorporation of heavy rock influences such as Kiss as "musical provocation". Grunge artists considered these bands "cheesy" but nonetheless enjoyed them; Buzz Osborne  of the Melvins described it as an attempt to see what ridiculous things bands could do and get away with. In the early 1990s, Nirvana's signature "stop-start" song format became a genre convention