Entertainment and boredom mean a lot to The Sleepwalk Collective, the Anglo-Spanish ensemble which brought one of the most beguiling experiences to the 2011 Edinburgh Festival Fringe.

As The Flames Rose We Danced To The Sirens, The Sirens placed audiences in an intimate arena to become a sounding board for one woman's cry for help amid a very private apocalypse. But Iara Solano Arana's solo performance was leavened by a brittle, deadpan humour that made light of her predicament.

This year the company returns with Amusements, another solo show performed by Solano and directed by Sammy Metcalfe that takes things even further. "We became fascinated with what our relationship with entertainment is, and what we want from entertainment," Metcalfe explains. "With television and laptops, you can become completely absorbed in a contemporary form of religious or shamanic experience, and that's a fascinating phenomenon. There's also an obsession with boredom, one of the great social problems of our age, trying to find the desire to do something that takes you over completely in as a way to deal with your own boredom."

Metcalfe and Arana have opted for a performance which sounds just as stark as its predecessor in terms of a lack of onstage movement. This time out, however, in a show that is largely sound-led, they have opted to equip the entire audience with headphones.

"Music is really important to this show," says Metcalfe. "Having the audience wear headphones means that the sound has a physical presence, so you get 45 minutes of having someone else's voice in your head."

The Sleepwalk Collective was formed at Rose Bruford College in London. The European Theatre Arts course which Metcalfe, Arana and the third founder member of the Collective, Finnish performer Malla Sofia Pessi, came together on was a particular inspiration.

"It's very theory-led," Metcalfe says. "It really encourages you to interrogate whatever you're working on. I think we wanted to be a physical theatre company for a while, but then we decided that we just wanted to hear someone talk, or not talk, or hear music, and that surprised us."

Between 2006 and 2008, the company developed work bilingually, first in London, then in Spain, where they found an affinity with dance companies. A five-hour piece, Why They Are Dancing, and Who Are They Dancing For, saw Metcalfe perform alongside Arana in headphones, while Nothing Left To The Imagination, was an exploration of emptiness that could last between 15 minutes and 24 hours. As The Flames Rose picked up awards last year in Kosovo, Bilbao and Birmingham, and Metcalfe now regards it as the show that found the company's minimalist voice.

"Lots of young artists now are dealing with the fact that they don't have any resources to work with," he says. "They work with what they've got, and that's what we do as well. I suppose a company like Forced Entertainment are the grandfathers of all of us in a way. They created a set of circumstances that could work in a particular way, in which, if you've got nothing to work with, you make a virtue of it."

Amusements will nevertheless be their first show to use full theatrical lighting. If this might be misconstrued as selling out, Metcalfe is aware that the company has to keep moving forward.

"We're starting to think about what we want to do next," he says, "and that's really quite frightening. The next show is going to have at least three people in it, and coming after two solo shows that's quite a big step. We don't want to keep on repeating ourselves, but the trick is to find how we use the limitations of the solo shows in a new context. So we could go anywhere, really, although I think the way to go is to keep imposing limitations on our work.

"Limitations are good."

Amusements, Summerhall, August 11-26, 5.45-6.45pm www.summerhall.co.uk