Sludge metal (also known as sludgecore or simply sludge) is an extreme style of music that originated through combining elements of doom metal and hardcore punk. It is also influenced by industrial music and noise rock, such as the work of early Swans, and may reflect both the dissonance and the experimental leanings of these styles. It is typically harsh and abrasive, often featuring shouted vocals, heavily distorted instruments and sharply contrasting tempos. While the Melvins from Washington laid the groundwork for both sludge metal and grunge in the 1980s, sludge as a distinct genre emerged after 1990 through the work of bands from New Orleans, Louisiana, such as Eyehategod, Crowbar, and Acid Bath, who generally borrowed from Southern rock. Later bands often border on stoner rock (e.g. High on Fire) or post-metal (e.g. Neurosis).