NEW YORK, NY.- If you start at the middle C of a piano and strike every key on your way up to the next C on the keyboard, you will play each of the 12 notes that make up an octave. Those 12 semitones are the foundation of most Western music.

But what if they were not? What if that same octave were equally divided into 14 tones, or 16? What if Beethoven had written the “Eroica” Symphony with a scale of 19 notes, or Schoenberg had written tone rows with 23? What would their music sound like?

Those were the questions that composer Easley Blackwood Jr., a pillar of the Chicago new music community who died last year, asked in his “Twelve Microtonal Etudes for Electronic Music Media” (1979-80). Composed for a project funded by the National Endowment for the Humanities, each of Blackwood’s “Etudes” shows off the qualities of different, often alien microtonal octaves.

It was an endeavor that took Blackwood, a composer of predominantly atonal music, in an odd new direction, said James Ginsburg, the founder and president of Cedille Records, which has released recordings of many of Blackwood’s works, including the “Etudes.”

“He became so fascinated with tonal writing through writing for other tunings,” Ginsburg recalled, “that after he did this, he suddenly changed gears as a composer, and started writing everything tonally.”

Blackwood recorded the “Etudes” on a synthesizer, and performing them live on acoustic instruments was practically impossible. But technology has evolved, and a new recording on Cedille, “Acoustic Microtonal,” illustrates to astonishing effect what this music might sound like if it were played by a chamber orchestra.

Behind the project is Matthew Sheeran, a 34-year-old British composer and a frequent collaborator with his brother, pop star Ed Sheeran.

During the pandemic, Matthew Sheeran arranged Blackwood’s scores into versions for traditional tuning, so that they could be recorded by 11 members of the Budapest Scoring Orchestra, each of them playing in isolation booths to create separate tracks that could be fed into a computer. Sheeran and Brian Bolger, the mixing engineer, then painstakingly retuned some 27,000 recorded notes to fit Blackwood’s microtonal octaves with Melodyne, one of the pitch correction programs used in pop and other recorded music.

The results are disorienting, yet convincing.

“I think that Blackwood was demonstrating that it’s possible to write tonal music using other than 12 notes,” Sheeran said in an interview. “When people hear the word ‘microtonal,’ they think of the word ‘atonal.’ I personally don’t actually mention any of this when I’m playing it to people. I just say this is attractive music, we can talk about that after you’ve heard it.”

Sheeran discussed the origins of the new recording and the detailed work that went into it. Here are edited excerpts from the conversation.

Q: When did you first come across Blackwood’s music?

A: When I was 17. It was at the time when I came across all music, really: 20th-century music, medieval music, basically the music you don’t normally hear on the radio. It was a big period of discovery, and Blackwood was just one of the many things that I discovered.

Q: And when did you decide to turn that interest into a project like this?

A: I wanted to start writing microtonal music myself, at the end of 2019. I’d wanted to do it when I was younger, at university, but the technology made it too difficult. I felt that maybe I’d missed the boat, but I found out how the technology had improved since then. You can now play these microtonal scales on a keyboard.

I thought I could orchestrate one of the Blackwood “Etudes” for a digital audio workstation, with sample libraries like Kontakt, just to try and learn about microtonal music. And it gradually escalated.

Q: Take me through the process. You have Blackwood’s old recording and scores, which look like familiar scores but have lots of odd accidentals in them. What did you do next?

A: Basically, that score needs to be translated. The first thing you have to do is get the score translated into what I call scordatura notation, where what you hear is not what you see. I had to translate it into music for keyboard, where the octave isn’t an octave. So if there’s 13 notes to the octave, a minor ninth or 13 semitones sounds like an octave when you play it on the keyboard. This is for the computer to play it back, to get guide tracks.

This version needed to then be translated into conventional music using normal accidentals. In the different tuning systems, some were easier to translate than others, and there were certain contradictory things because of the new geometries of music theory that couldn’t be translated. Often, you had to choose between either the harmony or the melody. Then I orchestrated that translation for the instrumentalists.

Q: So what you gave to the instrumentalists looked like fairly typical music?

A: Yeah, they didn’t need to know any of this.

Q: They just needed to play what was in front of them, and it might sound weird, but —

A: No, it doesn’t sound weird. The whole point is to try and make it not sound weird, so that they just play it as though it’s conventional music. I was trying to make a fake real recording. That was the hardest thing about this project. It had nothing to do with the microtonality — it was about making this stuff sound vibrant and spontaneous when it’s not that at all.

Q: And all that was dictated by the need to record it instrumental line by instrumental line, so that you could feed it into Melodyne and Auto-Tune it?

A: Absolutely.

Q: So you had all the tracks, and then back into the computer they went, to retune them.

A: I did it visually, but you check aurally at the end, and if you hear anything other than a unison, then you know there’s a mistake, and you correct it.

Q: Which of the “Etudes” do you find particularly interesting?

A: Blackwood liked certain tunings more than others, and some of them he really didn’t like at all. The ones he didn’t like are the ones I like the most, because he really had to think outside the box for them.

So 14 notes — he really didn’t like that one, and it’s an incredibly exciting, rhythmic piece. There was nothing in common with 12-tone tonal music in 23 notes, so he looked to the scales of gamelan, the slendro and pelog scales.

Q: This seems to be what fires you up, music that goes in a different direction, music that people don’t usually hear.

A: Yeah, when I was studying, my feeling about the way that contemporary music was taught in British universities and conservatories was that it seemed very hard to teach composition, but you could teach orchestration. If you teach orchestration, then a lot of people’s pieces show off what they can do with orchestration. I wanted to react against that. I look at a piece by Bach, and I’m like, this looks like it was written for the violin, but it was written for keyboard. Why does his music work on every instrument?

I think that’s what attracted me to the Blackwood “Etudes,” because multiple arrangements work with them, either electronic or acoustic. I had no idea what it was going to sound like, and I remember listening to one of them, and I was just viscerally shocked by it. But my ears have now got used to them, and they don’t even sound microtonal to me.

This article originally appeared in The New York Times.