The Mars Volta has a signature style: high-pitched vocals, masterful guitar, and epic songs that run through many more than the expected verse-chorus changes. Some criticize the band for their self-similarity, but with some quick observation it's obvious that The Mars Volta use their music and their knowledge of music to evoke different moods, tones, and attitudes. "Wax Simulacra" might have the same high-pitched rapid-fire vocals and guitar solos as most other Mars Volta songs, but the music evokes the setting of the entire album, masterfully meshing the contemporary, electronic downpour of distorted notes with the sounds of an ancient culture (much like the album cover). This has to do with the key signature. The technical term for the key that the song is in is E double-harmonic major. What a mouthful. We can call it the Byzantine or Arabic scale instead. Byzantine refers to the ancient city of Byzantium (which then became Constantinople, the capital of the Eastern Roman Empire – also called the Byzantine Empire – which eventually became Istanbul... ahhhh!), which was located in what is now Turkey. Anyway, the scale is referred to as such because it approximates the sounds of some of the traditional music of the area.
It's easiest to hear the scale in the melody during the verses. The guitar's melody clusters around E and D# and B and C. These clusters of notes that are right next to each other on guitar, and the big space between a C and D#, are characteristic of the E double harmonic major scale. It is a very fitting scale to use considering the flavors of the lyrics and the background of the music. The album is drenched in Middle Eastern terms and history. The names of some of the other tracks make this obvious enough. "Metatron" is not a Transformer robot, sorry, but it is the next best thing: an angel in Judaism. Then there's "Goliath," from the old David and Goliath myth, and "Ouroboros." An ouroboros is an ancient symbol of a snake eating its own tail. Then there is the history of the album, all stemming from a haunted ouija board that the band bought in Jerusalem.
As for the rest of the sound aspect of the song, not much stands out. Like a lot of prog. rock, the song bounces between time signatures – try counting out the chorus, it oscillates between 6/8 time and 5/8 time (where you'd normally hear pop songs in 4/4) – and uses unusual instruments for rock music, such as the saxophone. Other than that, the song is WAY more straightforward than The Mars Volta's standard fare. Instead of the sweeping, 8-minute long epics that characterize the rest of the album, this song is a simple verse-chorus-bridge tune that lasts barely 2 minutes and 30 seconds. Is the content of the song just that frantic? Or does this have to do more with the music industry itself – an industry where careers are made not with rock epics but songs short enough to get radio play? It may not be an accident that this song ended up being the band's biggest hit.