We're talking capital letters in the capital city.

Upper case versus lower case, the sort of thing that, on the Edinburgh music scene, separates FOUND from eagleowl. Two members of the latter band (singer-guitarist Bart Owl and violinist-guitarist Malcolm Benzie) are debating the finer points of typography with me in the back room of the Oxford Bar in Edinburgh, and clearly prefer a lower-case consistency. Which is fine in a continuous prose article printed in a newspaper until you start throwing in album titles and song names. At that point, it can become difficult for the uninitiated to spot where the journalism stops and the music-making begins.

"I'm fine if I see Eagleowl in the paper and it's got a capital 'E'," insists Bart. "There's a descending scale. If it's Eagle Owl, as two separate words, then I get annoyed. If it's eagleOwl, with a small 'e' and a capital 'O', I get quite angry."

"Wait until we start insisting it has to be a certain colour and font as well," threatens Malcolm.

Of course, there is no sense of anger or threat where the members of eagleowl are concerned (yes, let's make concessions for the band name, although I'm sticking with initial caps when the song titles come along). They're a notably mild-mannered bunch whose slow-build, lo-fi indie does, it has to be said, somehow suit the hushed design of a lower-case name.

The band began in a folksier incarnation of the duo in front of me many moons ago, before developing into a four-piece with Rob St John (keyboards/harmonium) and Clarissa Cheong (double bass). It was this line-up that released the excellent For The Thoughts You Never Had and Into The Fold EPs, as well as the gorgeous Sleep The Winter single, and which was, four or five years ago, part of a burgeoning Edinburgh indie-folk scene along with the likes of Withered Hand, Meursault and Benni Hemm Hemm.

However, it's with another two members on board – cellist Hannah Shepherd and drummer Owen Williams – that eagleowl begin the next, long-awaited chapter of their history with the release of their debut album, This Silent Year.

"We'd been playing together for such a long time, it felt like we probably should have an album," admits Malcolm. "It's a landmark in your time in a group, to get a solid statement, a solid body of work together on one album."

This Silent Year is a great piece of work. It showcases the trademark restraint that is always at the heart of eagleowl's music, but while older songs were often extended exercises in musical texture, the new ones have a better sense of song structure, something Bart puts down to the new set-up.

"It's not something we were conscious of when writing the material," he says. "Maybe it's got something to do with working in a bigger group and using the dynamics of the drums that gives it a more definite verse/ chorus thing."

It also, I suggest, puts a bit more pressure on him to deliver as a vocalist.

"Really? I was hoping that because there were more people ... Hmm, I prefer it to have group vocals and dual harmonies. I'm a bit more comfortable with that kind of set-up. I don't really see myself as a frontman."

"You still stand at the side of the stage when we're playing live," notes his bandmate.

I've seen eagleowl live several times over the past few years, and so was quite surprised by what the addition of a full-time drummer could do to the band ("Not even Charles Atlas was able to transform a 98lb weakling into such a brawny beast as blasted through the support set's climax," was the apt phrase in my review of their gig alongside Fence Records boss The Pictish Trail at The Caves in Edinburgh earlier this year).

It means eagleowl – and This Silent Year – are harder to pin down to a single genre these days. Bart's low-key croon-and-strum style comes from somewhere at the introspective end of the indie spectrum. The double bass and cello provide a classical chamber quartet foundation for the sound, although that bass can pluck a jazzier note when required, while the harmonium drone and fiddle phrases insert a more traditional folk flavour than is typically heard in other so-called indie-folk bands from around these parts.

And the drums ... well, on showstopper Too Late In The Day, the distorted guitar chord that detonates at the 6.42 mark isn't so much the culmination as a starting pistol for a further five minutes of skin-pummelling and cymbal-crashing that channels the spirit of Keith Moon.

"I think the connection with folk music is getting more and more tenuous," says Bart. "I see it more like folk in instrumentation, but the songs aren't really folk songs that tell a story. I'm quite happy with cutting that cord."

"I quite like being able to sound like that, so it doesn't fit into easily classifiable things," adds Malcolm. "But it does make it difficult to describe when people ask us what kind of music we play ..."

This Silent Year is released on Fence Records on May 13. eagleowl play album launch gigs at the Pleasance Theatre, Edinburgh on May 10 and The Glad Cafe, Glasgow on May 12