Amthem — not a typo — performs experimental, post-rock music. Post-rock is a form of experimental rock characterized by the influence and use of instruments commonly associated with rock, but using rhythms and “guitars as facilitators of timbre and textures” not traditionally found in rock. Post-rock bands are often instrumental.
Although firmly rooted in the indie or underground scene of the 1980s and early 1990s, post-rock’s style often bears little resemblance musically to that of contemporary indie rock.
The post-rock sound incorporates characteristics from a variety of musical genres, including krautrock, ambient, prog rock, space rock, math rock, tape music, minimalist classical, British IDM, jazz (both avant-garde and cool), and dub reggae, as well as post-punk, free jazz, contemporary classical, and avant-garde electronica. Early post-rock groups also often exhibited strong influence from the krautrock of the 1970s, particularly borrowing elements of “motorik”, the characteristic krautrock rhythm.
Post-rock compositions often make use of repetition of musical motifs and subtle changes with an extremely wide range of dynamics. In some respects, this is similar to the music of Steve Reich, Philip Glass and Brian Eno, pioneers of minimalism. Typically, post-rock pieces are lengthy and instrumental, containing repetitive build-ups of timbre, dynamics and texture.
Vocals are often omitted from post-rock; however, this does not necessarily mean they are absent entirely. When vocals are included, the use is typically non-traditional: some post-rock bands employ vocals as purely instrumental efforts and incidental to the sound, rather than a more traditional use where “clean”, easily interpretable vocals are important for poetic and lyrical meaning. When present, post-rock vocals are often soft or droning and are typically infrequent or present in irregular intervals. Sigur Rós, a band known for their distinctive vocals, fabricated a language that critics call “Hopelandic” (“Vonlenska” in Icelandic, a term even used by the band), which has been described by the band as “a form of gibberish vocals that fits to the music and acts as another instrument.”
In lieu of typical rock structures like the verse-chorus form, post-rock groups generally make greater use of soundscapes. As Simon Reynolds states in his “Post-Rock” from Audio Culture, “A band’s journey through rock to post-rock usually involves a trajectory from narrative lyrics to stream-of-consciousness to voice-as-texture to purely instrumental music”. Reynolds’ conclusion defines the sporadic progression from rock, with its field of sound and lyrics to post-rock, where samples are stretched and looped.
Source: Wikipedia