Nathan Gunn has the kind of smooth, seemingly-effortless baritone that you could listen to all night. But it’s an endurance test to listen to the seventy-five minutes of the one-person opera In Our Daughter’s Eyes, presented as part of this year’s Prototype Festival, and that has nothing to do with his voice.

Gunn portrays a man expecting his first child, and he expresses his excitement and his fears as he takes us through all the stages of the pregnancy – the first ultrasound, the second ultrasound, naming the child, etc.

Even before he knows the sex of the child, he tells us that he has to find a way to start acting like a grown-up and learn to be a father. (One can’t help but think of Rodgers & Hammerstein’s beautiful “Soliloquy” from Carousel.) Though Mr. Gunn’s character appears to us to be “a dad’s dad” – the kind, for example, who is handy in a woodshop – he reveals that inside he’s very much still the little boy who liked to play with airplanes and pretend to fly.

All of this is invading his sleep and there are several arias where he describes his dreams.

So what does composer Du Yun do with all this material? She won the Pulitzer Prize for her multi-layered and complex opera Angel’s Bone, but here she has written for Mr. Gunn a bland recitative in a mostly limited range of tuneless notes. The small orchestral ensemble is behind him, working very hard, but not really accompanying him, blaring under the one-dimensional vocal lines.

Thanks to the clever staging of director/librettist Michael Joseph McQuilken, Mr. Gunn is the hardest working man in show business. He changes the scenery, moves set pieces, builds props, dives into a hole in the middle of the stage and pulls himself up by hanging straps so that he can appear to run suspended in mid-air. He sings through most of it, but there are strictly instrumental passages while Mr. Gunn builds a crib or removes floorboards, and they seem endless.

The libretto describes the hopes and optimism of an expectant father, but then takes a tragic turn. The heartbreak for real-life parents in this situation is unimaginable. But some subjects, no matter how dramatic or poignant, don’t necessarily translate to the stage. Suffice it to say, this may be the first opera trying to tackle the issue of infantile organ donation.

Mr. Gunn helped create this piece, so he does share the responsibility for the results. Program notes describe how drawn he was to the subject matter. It would be preferable to hear him once again in concert singing Billy Bigelow.