If it is about only heavy metal then there is a short answer. But if its about metal, the whole genre then there is a very long answer. But since you asked for heavy metal that why I am going to write about only heavy metal. 1. read more
Essentially, the music needs to feel like its building up pressure or suspense..: there are many calm heavy metal songs too, and you can tell that its still metal because it still has distorted guitars. read more
For many artists and bands, visual imagery plays a large role in heavy metal. In addition to its sound and lyrics, a heavy metal band's image is expressed in album cover art, logos, stage sets, clothing, design of instruments, and music videos. Down-the-back long hair is the "most crucial distinguishing feature of metal fashion". read more
Its the same reason that Tool, while not being heavy metal, sounds heavy. Adam Jones's writing for guitar makes use of note choices and chord combinations that evince a certain kind of response. The same principle is present in every single genre, not even just metal. read more