In 1969, Karlheinz Stockhausen wrote: ‘Stimmung will reduce even the howling wolves to silence’.

It was as good a way as any of evoking a work written for six singers and six microphones that’s been described variously as ‘an extended madrigal’, ‘inscrutable’, and ‘the ultimate in Aquarian high culture’. According to legend, Stockhausen composed it in the winter of 1968, in Madison, Connecticut, staring out at the snow and ice on Long Island Sound while reflecting on his recent visit to ancient Mexican ruins.

His second wife, Mary, had rented the house where they were staying with their two small children. In order not to wake the children when he composed at night, he hummed the notes, becoming increasingly obsessed with the overtones – or natural harmonics – they produced.

This spring, London Voices – famous for performing everything from Tallis to Star Wars soundtracks – will deliver its interpretation of the work at Wigmore Hall. Stimmung, which variously translates as ‘mood’, ‘vibe’ or ‘pitch’, was initially commissioned by Collegium Vocale Köln (as distinct from Collegium Vocale Gent), a group that specialises in Early Music and contemporary works. More than an hour long, the piece is divided into 51 ‘models’, or mini movements, each based on the overtones of B flat. These overtones manifest as stacked intervals which become progressively smaller, beginning with an octave above the original note, then a perfect fifth above, a perfect fourth, a major third, a minor third, and so on.

It’s up to the singers to choose the order of the movements, as well as where to insert the names of gods from belief systems including those of the Aztecs, Ancient Greeks and Hindus. Beyond that there’s some erotic poetry, written by Stockhausen – referencing everything from avocados to the idea that his penis is his soul – which thankfully has to be performed in German.

I talk to Ben Parry, who took over the directorship of London Voices from its late founder, Terry Edwards. Sitting in his kitchen at home, he provides a wonderfully lucid and articulate analysis of Stockhausen’s opaque masterpiece, as well as demonstrating overtone singing that certainly puts Zoom’s audio transmission through its paces.

What aspects of Stockhausen’s life have you taken into account to prepare Stimmung?

Stockhausen assumed he was from a different planet – the planet Sirius. The idea of cosmic, celestial inspiration was at the forefront of his mind. He believed that everything in the universe resonates, whether it be a person or an instrument or something much larger, like the stars and the moon. When he was composing Stimmung, he carried this through to his investigation of the natural overtones in the voice.

Why did he home in on B flat as the fundamental tone for the piece?

I’m not quite sure why he decided to use B flat, although, interestingly, it is a wonderful note to sing. There are lots of great choral pieces in B flat major [such as Stanford’s Te Deum or Schubert’s Mass in B flat]. Stockhausen came up with the idea that you can create a chord, B flat major, with an added ninth just by using overtones, which is very interesting. The whole idea of it slightly falls down when everybody sings overtones on their own note. Because, of course, if you sing a D, then the overtones produced by that are different from those produced if you're in B flat. But there are certain points when everyone sings the same pitch, and that’s exciting, because the overtones really ring out.

How, at the most basic level, does a singer produce overtones?

In its simplest form, you change the sound you are making from a hum – which is the voice’s most closed sound and has no overtones – to more open sounds by, for example, going through the spectrum of vowels, A – E – I – O – U. You can use other combinations. At the same time it helps to sing a bit nasally and change the shape of the mouth by, for instance, pushing your tongue against the hard palate. We’re also using electronic microphones – so you can turn the bass down. This means you get less of the fundamental note and more of the ringing harmonics.

It’s an immensely hard piece to perform. The vocal ensemble Singcircle took six months to pull it together. How long did it take you?

I’m a bit of a geek with this piece, so I could explain quite clearly how it was going to work. It certainly didn’t take six months. I actually first sang it with Singcircle – I myself only had a couple of rehearsals – so I got very meticulous about it. When I left Singcircle I went to Scotland and cofounded the Dunedin Consort. We performed it live on Radio 3 in 2000. Stockhausen rang me up and said: ‘I like the way you are performing this. Come and work with me for six months.’ It was flattering, but I said ‘No!’ I never met him in the end, though he sent me notes periodically. He was very particular. When [baritone] Paul Hillier staged Stimmung with Theatre of Voices, there were stories that Stockhausen even tried to control the precise size and shape of the cushions they sat on.

Have you had other experiences of performing Stockhausen?

London Voices performed in Graham Vick’s production of Stockhausen’s Mittwoch aus Licht in Birmingham in 2012. The opera should be unstageable, not least because there’s a scene where the players of a string quartet are in four separate helicopters. London Voices performed the second choir scene, the Michaelion – set in a galactic headquarters where delegates are electing a new president. The favoured candidate is Lucikamel – a Bactrian camel. As you can imagine, it was an extraordinary experience. Kathinka Pasveer [the flautist who was Stockhausen’s close collaborator and one of the guardians of his estate] was doing the sound projection, and I talked to her at length about how the work came about.

What has been the most difficult aspect of bringing Stimmung together?

Obviously, we do it unconducted. So what’s essential is to feel both authority and a sense of ease so that when the model [or short movement] is passed to you from the singer before you, you understand how you're going to transition from that model into the one you're singing. That means understanding the tempo, the pitch and the phonetics. Everybody's got to listen really intently. Stockhausen didn’t want to be too specific, so one of the miracles of this piece is that it can go off in different directions. When you come together and all the overtones are ringing, it creates this wonderful, ethereal, cosmic sound.

What’s the most interesting reaction you’ve had to it?

We performed it in King's College Chapel in Cambridge in 2015, which has the most extraordinary acoustic. An audience member came up at the end and said, ‘I loved hearing this. I was backpacking in a Norwegian forest, and when we slept outside one night I heard this kind of sound in the trees.’ My aunt, who was with me, who is a Buddhist, said ‘Of course’. She explained that certain modern interpretations of Buddhism say that music is in the ether, and as composers, we are literally drawing it from the ether and committing it to paper. It’s a slightly 1960s, Zen way of thinking about this piece, but for me it really resonates. Not least because that’s what Stockhausen felt too.

This article was originally commissioned for The Score magazine in Spring 2026. The Score is Wigmore Hall's exclusive Friends magazine, published up to three times a year.