Noisecore is a derivation of Grindcore/Hardcore Punk. Has been use as a term since mid/late 80’s and stabilized itself as a own genre.
The songs are usually chaotic short blasts of noise, accompanied by screamed, growled, or shouted vocals. While there is some instrumental variation (some groups use drum machines, others use completely non-musical noise sources), Noisecore acts tend to use a guitar and/or bass guitar.
Earlier releases tagged as "Noisecore" tend to be a raw, chaotic, and lo-fi form of Hardcore; artists in this style include Tranquilizer (2), Kuolema, and Brigada Do Ódio.
Napalm Death's "You Suffer" is generally considered the blueprint for most later Noisecore, being approximately one second long. Tracks can go to even couple dozen of seconds, but hardly ever reaches length of 1 minute or so.
Typical Noisecore releases (whether singles or LPs) can contain forty or more songs, with some releases claiming to contain thousands of tracks.
Lyrical content varies from highly political (Seven Minutes Of Nausea, Fear Of God) to the gross/offensive (later Anal Cunt, Gore Beyond Necropsy) to the absurd/surreal (Sore Throat, Minch); some acts (early Anal Cunt, Genital Masticator, The Gerogerigege) use wordless vocal sounds.