Halldorophone

The halldorophone (/ˈhældɔːrɔːfoʊn/; also known as the dorophone, and dórófónn in Icelandic) is a cello-like electronic instrument created by artist and designer Halldór Úlfarsson.^[2] The halldorophone is designed specifically to feedback the strings,^[3][4][5] making use of the phenomena of positive feedback to incite the strings to drone. The instrument gained some recognition in early 2020^[6][7] when composer Hildur Guðnadóttir won the Academy Award for her original soundtrack to the movie Joker, some of which was composed with a halldorophone.^[8][9][2]

A halldorophone owned by the Iceland University of the Arts. It was commissioned by the Design Fund in Iceland and gifted on January 17th 2022.^[10]

halldorophone

A 2018 halldorophone with a combined neck and fingerboard in cast aluminium.
Electronic instrument
Hornbostel–Sachs classification	513[1] (Electrophone)
Inventor(s)	Halldór Úlfarsson
Developed	2008 -

Operating principles

The halldorophone is an electroacoustic instrument that makes use of positive feedback as a key element in generating its sound. The player takes a sitting position behind the instruments and plays it a similar way as they would a cello. The instrument is predicated on audio feedback that is generated when sound picked up by a microphone (or comparable device) is passed to a speaker and then re-detected by the microphone. It causes amplification in the system and a sustained, recursive signal flow is created; a positive feedback loop.^[11] According to its creator Halldór Úlfarsson, the halldorophone is designed to distill feedback as its core identity, making it a fundamental compositional element rather than a by-product.^[12]

In the words of composer Nicole Robson: "The halldorophone utilises a simple system, whereby the vibration of each string is detected by a pickup, amplified and routed to a speaker embedded in the back of the instrument. By adding gain to individual strings in the feedback loop, the instrument's response can become rapidly complex, potentially spinning out of control. While every musical performance of a piece is unique in some way and contingent on its particular moment and situation in time, the unstable nature of the halldorophone exacerbates this condition."^[13]

Electronics engineer Orfeas Moraitis who has worked on halldorophone electronics with Halldor Ulfarsson since 2018 recorded an instructional video for an experimental version of the instrument at Elektronmusikstudion in Stockholm at the start of summer in 2022 at the occasion of the instrument being on loan to EMS and available to users along with other studio instruments and equipment.^[14]

Uses

Concert music

A number of pieces have been composed and performed for solo halldorophone, halldorophone in duet with a second instrument, and with ensemble.

Several composers of the Icelandic S.L.Á.T.U.R. collective have used halldorophones in their works after the Hljóðheimar exhibition in Reykjavík 2011.^[15]

Hafdís Bjarnadóttir's piece "A Day in February", for halldorophone and accordion, was nominated by the Icelandic National Broadcasting Service for the International Rostrum of Composers in Vienna in 2011.^[16][17]

Timothy Page premiered "Toccata" for halldorophone, clarinet, and electronics at the 2012 Nordic Music Days in Stockholm.^[18]

The Icelandic composer Guðmundur Steinn Gunnarsson wrote a suite for solo halldorophone, Hafið og Örninn, which premiered at the 2015 Hljóðön concert series by the Finnish cellist Markus Hohti. ^[19] His chamber opera Einvaldsóður, which premiered on Sláturtíð 2017, ^[20] makes extended use of the halldorophone in a chamber music context. It was selected as one of the top 5 pieces of its decade in Aesthetics for Birds.^[21]

Secondson, an artist from the United Kingdom, performed with the halldorophone at The National Museum of Wales for an improvised performance including Cian Ciaran and The Gentle Good on 19 August 2019. It was the first live performance with a halldorophone in the United Kingdom.

Secondson plays halldorophone at the first live performance in the United Kingdom involving the instrument

Nicole Robson, of the United Kingdom, performed a study for solo halldorophone "Dual/duel/duet/for/with/halldorophone" at the New Interfaces for Musical Expression conference in 2020.^[13]

Swedish composer Johan Svensson has composed two works for halldorophone and a second instrument.^[22]

In December 2021, Mason Cook, Sherry Gao, and Forrest Love, music composition students under the tutelage of Adam Schoenberg at Occidental College, debuted a series of new works for the halldorophone, which the college had acquired earlier that year. This was the first time that the halldorophone had been showcased in the Americas.^[23] Schoenberg would later use the same instrument from Occidental College in May 2022, at a Latin American-themed festival by the Louisville Orchestra in Kentucky, where he premiered his piece "Automation". It is a double concerto for orchestra, cello, and a custom built halldorophone. The conductor, Teddy Abrams, said using the electronic instrument was in keeping with the energy of the city and the orchestra's history: both daring and adventurous.^[24][25]

Film music

In 2016, composer Jóhann Jóhannsson recorded Hildur Guðnadóttir playing halldorophone for his score of the motion picture Arrival.^[26]

In 2018, Icelandic composer Hildur Guðnadóttir scored the film Sicario: Day of the Soldado using a halldorophone, which she claimed was her main instrument at the time. She called the instrument an "electro-acoustic feedback monster" and a "Jimi Hendrix cello".^[27][28]

In 2019, Hildur Guðnadóttir played and composed the original soundtrack to the movie Joker using a halldorophone. The score won the Academy Award for Best Original Score the following year. ^[29]

Studio recordings

In 2025, cellist and composer Martina Bertoni released the album Electroacoustic Works for Halldorophone (Karlrecords), composed during a residency at EMS (Elektronmusikstudion) in Stockholm. The halldorophone was used as an algorithmic system to explore tunings and harmonic relationships, with minimal physical intervention (such as strumming or plucking). The resulting compositions highlight the instrument's generative and feedback-responsive properties in electroacoustic music.^[30][31]

Drone metal band Sunn O))) recorded halldorophone with Steve Albini at Electrical Audio on its eighth studio album, Life Metal, released in 2019.

Halldorotones, a collection of short pieces for solo halldorophone, was released by Broken Strings Music in 2020.^[32]

Secondson released the score Tónlist frá: hér að neðan on 1 October 2019, prominently featuring the halldorophone and Yamaha CS60. On 8 February 2021, he followed with Suite for Halldorophone and Synthi A, a 21-minute ascending drone piece. His next release, Any Other Place, came out on 10 March 2022 and was recorded in the crypt of the Temple of Peace in Cardiff.^[33]

The Icelandic electronic collective Cryptochrome released its EP Love Life on 2 February 2020, which features the halldorophone on the song 'Kali.'^[34]

Greek melodic death-black metal band Temor recorded its album My Sorrow's Rage, which features the halldorophone played by Konstantinos Chinis.^[35]

Video games

In 2021, composer Hildur Guðnadóttir composed the video game score for Battlefield 2042 by DICE (company) and EA Games using the halldorophone. The soundtrack was released on 10 September 2021.^[36][37]

Festivals

In July 2024, the halldorophone was featured at Sónar+D, an international festival exploring the intersection of creativity and technology. As part of the Intelligent Instruments Lab exhibition stand, the instrument was presented with custom DSP running on a built-in Bela microcomputer. Three programs running on the Bela were presented through the duration of the exhibition, developed respectively by composer Davíð Brynjar Franzson and IIL PhD student Victor Shepardson, which set the instrument to play generative composisitions autonomously, and a patch developed by the Lab's  principal investigator Prof. Thor Magnusson, which modified the behaviour of the halldorophone tailored to his preferences when being played by an instrumentalist.^[38]

History

A halldorophone from 2014

The instrument was originally conceived of as a prop for performance art during Halldór Úlfarsson's time as a visual arts student. He says that it began as a joke but in time developed into a functional string instrument for string players interested in working with feedback.^[39]

The halldorophone was developed through over a decade-long iterative design process in close dialogue with performers and composers. Each instrument was presented as a fully functional version and entrusted to dedicated artists, not as test subjects but as collaborators who used the halldorophone in serious musical contexts. This informal yet sustained collaboration shaped the instrument’s evolving form and expressive capabilities. Rather than following a linear technical development path, the halldorophone’s identity emerged through cycles of artistic experimentation, cultural placement, and mutual feedback.^[40]