Reading descriptions of Julianna Barwick’s music brings to mind an old quote, credited variously to Frank Zappa and Elvis Costello.

‘Writing about music is like dancing about architecture.’

The New York songwriter is often said to make ‘ethereal’ and ‘abstract’ music, vague terms that really don’t reveal much at all about her songwriting. Not that this is only the fault of journalists – Barwick herself struggles to define her multi-layered sound.

“I still don’t really understand it,” she sighs down the line from America. “I don’t even know how to accurately describe it. It doesn’t fit neatly into genres. Somebody said it was ‘dream-pop’ once. I don’t know.”

Barwick uses loop pedals to pile vocal melody upon melody, combining her voice with ambient textures and keyboard lines to create a mystical, haunting palette. Her third studio album, Will, came out earlier this year to critical acclaim.

As a child who was always singing, she would seek out unusual locations that offered good resonance and echo, like stairwells and empty corridors. Now, she says, she gets tips from fans.

“I’m always looking for places like that. I actually had someone email me saying, ‘I know you’re going to be in Scotland soon, and there is this building that has a 30-second-long reverb in it. You should check it out.’ People will send me suggestions like that.”

The process of layering melodies sounds staggering to somebody without a musical ear – it is difficult enough to dream up one tuneful harmony, let alone envisaging several at a time.

Barwick, however, is “hard-wired for melodies,”

having performed choral music at school and at church since she was a child.

“It’s intuitive, and not something I really think about that much.”

This instinctive approach contrasted with that of Sigur Ros’s Alex Somers when the pair recorded together in Iceland in 2012. Barwick grew up without paying too much attention to technical aspects like keys and pitches, and was in for a lesson when meeting the meticulous Somers.

“You know, I just make everything up on the spot, and he’d be wanting to add strings and everything to it,” remembers Barwick.

“One day he was like, ‘you have to re-record that whole thing,’ and I was like, ‘no, why?!’ He said it wasn’t in the right key. The voice wasn’t matching with the piano.”

The singer cites Sigur Ros as an influence – as well as soundtrack music – partly because of their vocal approach. The Icelandic band invented their own language for their lyrics, which, far from alienating audiences, gives them a more universal appeal, says Barwick.

“There are no discernible words, which allows you to get lost in it and have your own experience with it.”

She has often opted for the same strategy, prioritising non-verbal sounds ahead of actual lyrics.

“It is mostly wordless, so I feel like people can interpret it in their own way. When I make music I’m very much in my own world.”

However you want to describe her music, Barwick’s upcoming tour will allow fans to bask in this unique, melodic universe.

Komedia, Gardner Street, Brighton, Thursday, August 25, 7.30pm, £13, 08452 938480