At the core of Mouthpiece is the female voice. When they started working on the multidisciplinary show, Amy Nostbakken and Norah Sadava—its creators, performers, and producers—felt it had yet to be expressed freely and to its full extent.

“We looked around trying to find a representation of an authentic female voice we related to,” says Nostbakken, reached by Skype together with Sadava at their Toronto homes. “We looked for one in popular culture, in movies, in literature and television that covers the whole spectrum of what it is to be a woman, and when we couldn’t find it we made this show. Our sounds include the guttural, the ugly… It’s hard to express with words what we do. It’s the dissonance in our heads when we’re thinking two polarized thoughts at the same time, or we’re confused, or feel rage. Sometimes a vocal sound is much more effective in expressing what that feels like.”

The two actors, who began working as a duo three years ago, play different parts of the same woman’s mind. “So what we’re communicating are the thoughts going on in her head but also the emotion, which often doesn’t have words,” says Sadava. “There’s no dialogue. We never really have a conversation. And we try to play with our voices in the text as well, in terms of how we speak in unison or in contrast to each other, when we’re taking turns, when we’re passing text back and forth.”

The mind in Mouthpiece belongs to Cass Hayward, who’s lost her voice, not just figuratively but physically, in the wake of her mother’s death. “She wakes up in the morning and finds it gone, so thematically this works for what we wanted to talk about,” says Nostbakken, who also directs and wrote the music for Mouthpiece. “We use our voices a cappella throughout, centred on ‘Look what two women can do on an almost-bare stage. You just have to open your mouth and speak.’ That’s the message.

“And we have to speak, because the show is so honest, it’s so revealing, and we’re so vulnerable,” she continues. “The way we wrote it is that we have to reveal the most embarrassing secrets we would never want anyone else to know. That’s why it was so terrifying to premiere. But the reaction was beautiful—not ‘Bravo, you did that,’ but ‘Me too.’ I think the show reveals how we normalize different ways that we’re oppressed and harassed in society. So we’re acting as a mouthpiece to inspire others to do the same, not only for themselves but for other women.”

The duo presents a kind of shortened history of the female voice in popular music. “We open in darkness and it’s just our voices, taking you through harmony and dissonance,” says Sadava. “Then you’re brought through opera and duets, we have the Andrews Sisters, Billie Holiday, Janis Joplin, Tina Turner, Joni Mitchell, Beyoncé, and women’s choirs.”

Mouthpiece is very demanding for the performers, who have to draw deep on their emotional resources while coordinating movements and voices with ease and precision. “When building up to the run that we recently did in Toronto, we bought a treadmill and stationary bicycle, and we’ll do the play while running and cycling,” says Nostbakken. “Musical-theatre actors and pop stars make it look so easy, but to sing and dance at the same time is the hardest thing. Norah and I are runners—we do half-marathons—but there’s nothing more exhausting than that. This show knocks you out because we have singing and dancing and acting as well; it’s an emotional show, it’s an hour long, we never leave the stage, and it’s very physical. We definitely have to look after ourselves; we don’t go off-stage to have a fag and a coffee.

“We’re nerds,” she adds, with a laugh that’s echoed by Sadava.