Time Signature
The trembling ear...
Genre: melodic black metal
Ave Maria is described as an experimental black metal band, but they but the music on "Chapter I" is not experimental in the same way that a lot of avant-garde black metal is.
First and foremost, Ave Maria experiment with melody, and their music is also more varied than your (stereo)typical black metal band. The black metal genre elements that define the genre are mostly present on this release though (such as the tremolo picking, the tense harmonies, the unpolished production, and the cold bleakness), and it certainly makes sense to argue that "Chapter I" is a black metal release.
There are also a couple of more typical tremolo-and-blasting passages in 'Impulses from the Sphere of Broken Larynx' and a section of 'Meandering through the Tunnel of Trance', but mostly we are dealing with midtempo music with inherently melodic riffs and lead guitar melodies, and there are also extended passages with clean guitars. The vocals are more in the vein of death growls than black metal snarling, but they suit the music quite well.
If you like melodic black metal with an authentic un-polished black metal sound, then you might be interested in checking out this release.