To the untrained ear, the sounds of death metal music can be a cacophony of heavy guitar, pounding bass and incomprehensible lyrics. But that's not the case for everyone.
Professor Bill Thompson, from the Department of Psychology at Macquarie University, has co-authored research published in the Journal of Music Perception which studied how well 64 participants understood words taken from death metal songs.
The research found fans got around two-thirds of the words correct and non-fans less than half, based on a multiple choice selection.
"Fans can decode [the lyrics] kind of in the same way that somebody familiar with a Scottish accent could understand a very strong Scottish accent when the rest of us can't," Professor Thompson said.
It's a death metal thing, you wouldn't understand
"Death metal music involves lyrics that are extremely hard to understand," he added.
"They're transposed down to a low-pitch register not used in speech, so people have to really listen carefully to be able to understand any of the lyrics."
The study found there was a real advantage for two groups of people: death metal fans, and musicians generally, regardless of whether they were fans or not.
"So, fans have this music-specific expertise at being able to comprehend these highly distorted lyrics.
"Being a fan is in a sense like having a version of expertise; it's almost like a proxy for a form of musical training."
The study subjects, fans and non-fans alike, were asked to listen to isolated words, so they weren't able to piece together meaning from a sentence where the sense was gleaned from the context.
And the researchers took other precautions, too.
"We made sure the death metal fans were not familiar with those particular songs, and we extracted them in a way that they had no idea what those words were," Professor Thompson said.
"We also balanced words that were kind of aggressive and likely to occur in a death metal song with lyrics that were kind of neutral, not particularly aggressive or violent words."
Fans were able to understand about two-thirds of the words they were asked to listen to.
This, said Professor Thompson, is not much different to normal conversational comprehension, where we fill in the blanks of words we don't hear or understand by using context to guide us.
Non-fans understood less than half.
Does listening to death metal lead to real-life violence?
The growling and screaming sounds of death metal vocalisation are usually associated with aggression and fear.
Professor Thompson and his team have been looking into whether fans are normalising violence by listening to violent lyrics sung in the distinctive death metal style.
He said fans viewed death metal as an artwork, and not as a real-life form of aggression.
"The aggressive violent lyrics is one way for death metal music to generate a very coherent community, a kind of in-group of people who understand and get it," he explained.
Non-fans are repelled by the music and the imagery, says Professor Thompson, and that helps draw a sharp boundary between the in-group and out-group.
"That's quite intentional in death metal; the social identity is really important," he said.
According to the research, it is still "an open question" whether the violent words and messages in death metal music cause aggressive thoughts and behaviour.
"What we're finding is that [fans are] not so much desensitised as actually people who are drawn towards, or gravitate towards, violent themes, or dark themes, in art works.
"And we're not sure why that might be, but we can't say that they necessarily are desensitised to violence in the real world.
"It's just that they seem to be curious about dark themes."
And for the record, in the audio at the top of the article — the first word is "being" and the second is "crushing".
