Today it is legitimate to ask where the new developments of contemporary music lie and in particular what happens to its most recent subdivisions. For example, the qualities of spectralism have long been invoked, a way of composing for instruments that has used (and still uses) spectrograms, sonograms and software for the microscopic detection of sounds. Tristan Murail, one of the main representatives of this compositional current, has always spoken of it as a revolution in the musical field and today, all things considered, one can certainly see the excellent diffusion that these compositional aids have had in artistic creation: many composers have taken up aspects of it, they use quarter tones as much as possible for the instruments, but few develop new strategies in musical theory that reenvision the ordinary parameters (harmonic, timbral, dynamic, etc.). One of the obvious exceptions to my reasoning is found in the music of the Dutch composer and poet Rozalie Hirs (b. 1965), whose interest in spectralism has found many ways to manifest itself; Hirs grew up musically among the teachings of Louis Andriessen and Tristan Murail, she understood their secrets while building an artistic vision for herself, extremely modern and connected to poetry, another field of art in which she, Hirs, is excellent. Hirs is an innovator in both music and poetry: in music she has repeatedly declared (also with essays dedicated to this purpose) the importance of the search for an aesthetic impulse that overcomes the limitations of what is generally attributed to spectralism through the mere activities of musical extraction, synthesis and addition: there are other techniques that can be followed, which lead to a new way of interpreting materials, creating new ones; in poetry, however, Hirs has set up a style that is the result of some influences that have been elaborated in a very efficient way: Hirs uses the syntactic constructions of apò koinù in an innovative way (the Latins and ancient English used them a lot), i.e. sentences in which a groups of words connect to the previous or next words, in such a way that this leads to two different grammar functions and subsequently meanings. Also, Hirs has experimented with a counterpoint of speech (i.e. simultaneously sounding sentences), rhythm of meaning (which would be the counterpart of harmonic rhythm in music), and speech melody (the intrinsic melodic qualities of speech).
When analyzing Hirs’ composition we note that the most innovative part of her work is found in the ‘spectral flows’ dedicated to ensembles and orchestras. In her beautiful website (see it here), Hirs has included a lot of informative support for her compositions, the acts of her research (1) and a quantitative division of her repertoire, establishing a threshold of definition between ensembles and orchestra identified in number of elements equal to 15. Putting aside the early works and considering the mature scores written for orchestra (>15 elements) we count 7 compositions which involved some of the main European orchestral and symphonic institutions (the Dutch Radio Philharmonic Orchestra and that of Zuidnederland, the Musikfabrik, Klangforum Wien, ASKO|Schönberg); Below, I list them in chronological order:
–book of mirrors (2001), for 19 musicians, is the result of a close collaboration between Rozalie and experimental film maker Joost Rekveld for a film based on the multiplication of light rays in prismatic structures or mirrors. Hirs sets the entire composition on a series of ratios that link chords and tones, and generate frequencies for timing (duration and rhythm) as well as harmonies, through sum and difference tones, inspired by the known psychoacoustic effect.
–roseherte (2008) is a piece for symphony orchestra and 150 custom-synthesized electronic sounds; there are two versions to date: the premiere version for 91 players, and a version for smaller orechestra reduced to 42 players in 2014, it is a composition inspired by the mythical animal the rosedeer (invented by the composer herself) and includes harmonies calculated with help of the OpenMusic software; the innovation lies in the application of ring modulation between several pairs of ‘dominant-seventh’ chords.
–atlantis ampersand (2015), for 18 instruments, 2 SATB-style choirs, and electronics, translates the flooding of the mythical city of Atlantis into what the composer describes as a classical oratorio, with many sound stimuli, harmonies and richness of resonances. The text given to the singers is a poem by Hirs, transcribed according to the criteria of the phonetic alphabet, which ultimately allows highlighting only the vowels of the words, as if we hear the people of atlantis from below the water surface as if they sing or speak after the city has disappeared underwater.
–the honeycomb conjecture (2015), for 22 instruments and electronic sounds, also is built upon harmonic partials and the calculation of additional frequencies. In this score, like in atlantis ampersand (2015), the microtonal deviations from the traditional semitones are notated above every pitch (in midicents), while the respective partial numbers are indicated under each note.
–lightclouds (2019), for 16 instruments and electronic sounds, is inspired by noctilucent (night shining) clouds, rare tenuous cloud-like phenomena in the upper mesophere of earth, consisting of light reflecting on ice crystals, visible from the ground only during astronomical twilight. This work again involves calculation of frequencies. The electronics fuse and merge with the instrumental parts in a search for multiplicities in texture and timbral color, wherein the brass instruments collectively are treated as a soloistical meta-instrument.
–avatar (2022), for orchestra, is composed as a companion piece to the Third Symphony of the nineteenth-century French composer Louise Farrenc; Hirs takes a musical quote from this symphony, subjects the original harmonic progression to frequency modulation, as if a light beam falls through a prism, multiplying into many different colors.
–Bron (2023), for symphony orchestra, offers a mysterious and lush soundworld, with a musical movement based on natural phenomena such as waves and gusts of wind. The long-sustained chords give the orchestra musicians space to tune the written pitches to each other and immerse the listener in a new sound world. The work is dedicated to the memory of György Ligeti.
As for the ensembles, Hirs gave a great contribution to spectral writing with compositions such as sacromonte (1997), with platonic ID (2006) and arbre généalogique arbre généalogique (2011, with soprano and electronics), pieces in which the composer constructs one of her first meditative forms of spectralism, builds overtones based on Plato’s harmony as described in Timaeus, or reinvents a new ‘lyricism’ of singing entrusted to the amazing skill of Susan Narucki. In 2022 the Donauschingen Festival commissioned artemis from her, again for soprano (Keren Motseri), ensemble (ascolta) and electronic sounds, which draws inspiration from some of her poems that intertwine the myth of Artemis with the feelings of the pandemic period and the ‘magic of the possible present’. A spectral instinct is also produced for string ensembles: in addition to the orchestral compositions that I mentioned before and which include string instruments, we must add lichtende Drift (2014), for string orchestra and then 4 string quartets, namely zenit (2010), nadir (2014, with electronics), hand in hand (2020, with soprano), and the miniature quartet adonis blue (2023).
Furthermore, and finally, there is the chamber and solo repertoire, that is also spectrally informed: article 5 [dolphin, curved time] (2008) for solo soprano, consists of distortions of simple melodic phrases and duration sequences. article 6 [waves] (2013), article 7 [ways to climb a mountain] (2012), and article 8 [infinity] (2014), solo works with electronic sounds for electric guitar, bass clarinet, and flute respectively; these three works also can be performed together to form the trio infinity stairs (2014). They are intrinsically related, because each solo piece is solely consituted of harmonies built from partials on fundamental notes present in the other two solo works, thus together constituting the trio work. The microtonal article 10 [prismes] (2021) for solo cello, commissioned by Radio France, consists of ring modulation of relatively simple melodic phrases that cover the different strings. These virtuoso pieces are among Hirs’ most demanding works to date.
Hirs’ way of working had an origin in the analysis of instrumental sounds performed by the composer with help of the software AudioSculpt. This program allowed her to analyze and view sounds. In addition, the composer processed the obtained spectra by filtering, compression, and interpolation. Aside from this empirical work, Hirs often carries out calculations based on idealized models for frequencies with help of the software OpenMusic: this forms a substantial part of her creative process for all above mentioned pieces.
The CD Pulsars released in 2010 provides a good showcase of her electroacoustic work with three attractive compositions (Pulsar/In La/Bridge of Babel) based on her own texts. These works propose a special ‘sonification’ of her words, which are completely dedicated to a new narrative, through superpositions, stratifications, and simultaneous flows of meaning. Recently Hirs has conducted further experiments through poetry linked to visual art, resulting in a dialogue between language, music, images (all found in her evening-length poetry and music cycle dreams of airs). Space is also important for Hirs and the demonstration of this can certainly be found in her art installation pieces, created in close collaboration with the architect Machiel Spaan, which focus on the creation of spatial sensoriality: these are interactive spaces that are explored by the user through GPS or movement sensors, while listening to poetry or music in an architecturally open environment (see what happens with reference to the concepts of Theo Van Doesburg’s open floorplan).
Hirs’s plural language hides a reward in terms of sounds and knowledge that are a rare find today in the contemporary music world.
For the benefit of the readers of Percorsi Musicali, I contacted Hirs and I thank her very much for accepting my invitation. Below I report our brief epistolary dialogue.
EG: I am very honored to host you on PM. I find your research very interesting and your music very fascinating. We know about you that you had a career in chemical engineering, which you gave up for composition and poetry. It is clear that you are among those people capable of manifesting their qualities in multiple ways. Do you follow the world of science in any way today? And if so, are there any concepts you would like to transfer into music?
RH: Thank you for your kind words and the introduction. My interest in science and research remains a vital part of my life, directly influencing my music and poetry. The ways in which sound interacts with us—the listeners—directly inform my compositions. My music is part of the spectral music tradition, emphasizing the detailed analysis of sound spectra and how these spectra can be manipulated to create new musical structures and textures. I frequently employ mathematical structures and algorithms to shape my musical works. This might include the use of Fibonacci sequences, fractals, or other mathematical models, such as the harmonic series, and frequency modulation, to determine musical parameters, such as rhythm, frequency (pitch), amplitude (loudness), and the spatial distribution of sound. This approach allows me to explore perception more deeply in order to forge connections between the listener and the music on a fundamental level, creating pieces that resonate with an almost instinctual familiarity on a deep, intuitive level with us. One could say that I follow the world of science not only as a source of inspiration but as a fundamental component of my artistic process. My work exemplifies how scientific concepts can be transformed into innovative musical and poetic expressions, creating a rich dialogue between these seemingly disparate realms.
EG: Your insights into spectralism led to a few articles on compositional techniques. Can you tell us briefly which innovative techniques composers should focus on in their work?
RH: The compositional techniques I have written about in the book Contemporary compositional techniques and OpenMusic (Paris: Ircam, 2009) are the result of my own artistic research during several creative processes. The articles also include discussions on the music of Tristan Murail, which are part of my doctoral thesis for Columbia University (Doctor of Musical Arts, 2007).
Every composer chooses the creative process they wish for, of course. I can only talk for myself: as a composer I like to delve into the exploration of sound itself, beyond traditional harmonic and melodic structures. This includes experimenting with frequency calculations to uncover new harmonic possibilities, and integrating electronic and acoustic sounds in order to forge a new dialogue and fusion of the two realms. Understanding and utilizing the physics of sound can lead to innovative compositional techniques, such as the modification of the overtone series or incorporating phenomena known from the science of psychoacoustics. In general, I like to emphasize the expansive potential of compositional techniques that draw from a deep understanding of sound’s physical and perceptual properties. Innovation isn’t about using new tools or technologies, but about approaching composition with a curiosity that pushes the boundaries of what music can be. It’s about listening deeply, imagining bravely, and crafting with precision and care. This perspective encapsulates not just a method of composing, but a philosophy of sound that invites us to explore the vast potential of musical expression.
EG: While writing this article I necessarily had to come across some of your incredible poems. My idea is that they insist on something that ultimately manages to satisfy both the need for an implicit narrative and the achievement of musicality. Can you explain to us what that particular form of lyricism that you called ‘seemingly archaic melody’, suggested in arbre généalogique, consists of?
RH: The idea of the “seemingly archaic melody” in arbre généalogique, commissioned by the ASKO|Schönberg ensemble and performed with soprano Susan Narucki in 2011, is merely to indicate that the melody remains relatively simple. Here, the lyrical poem remains central to the work, drawing upon modal melodic patterns reminiscent of earlier music periods, but also of folk music and nursery rhymes. This kind of melodic writing stays close to the human voice. At the same time embedding it within frequency calculations that are completely in acocordance with our ears. This blend is a fascinating confluence of the intuitive and the analytical. It exemplifies how one can harness the precision of scientific methods to enhance and inform the emotional and aesthetic dimensions of music. The result is a compositon that feels both familiar and novel, connecting listeners to a sense of the universal, the archetypal, through sounds that transcend specific temporal or cultural connotations.
The frequency calculations I developed for arbre généalogique consist of mainly sum and difference tones, which would also naturally ocur in our brain while listening to the simultaneously sounding soprano and bass lines. They serve as a foundation upon which the melodic and harmonic content is built and transformed. These calculations are not arbitrary; they stem from investigations into the nature of sound itself and into how we perceive sound. By meticulously analyzing and calculating the frequencies of my soprano and bass lines, I aim to sculpt sound with a level of detail and clarity that traditional methods might not achieve. This scientific approach allows me to create new harmonic progressions and timbral nuances that are both rich and precise, offering a sonic landscape that is deeply resonant and full of subtle intricacies. This ensures that the melody does not exist in isolation but is embedded within a harmonic framework that is both complex and coherent. Moreover, this approach enables me to play with listeners’ perceptions, subtly altering the way they experience melody and harmony. By carefully shaping the sound’s frequency content, I can create moments of tension and release, brightness and darkness, familiarity and alienation—all of which serve to deepen the emotional impact of the music in an invitation into new sonic territories.
EG: I’ll ask you an impertinent question that I have also asked Dufourt, Bedrossian and other composers and which concerns the fact that almost all spectral composers have historically concentrated on quarter tones. Why do you think this happened?
RH: Understanding spectral composition involves grasping pitch as a concept existing along a continuous spectrum of frequencies and utilizing absolute frequencies alongside other musical parameters when creating electronic sounds and composing instrumental scores for live performances.
Transcribing these frequencies to the score in a musician-friendly manner, however, can pose challenges. Traditional music notation relies on twelve-tone equal temperament, representing semitones (1/2-tones), thus not capturing all spectral frequencies and pitches accurately. Consequently, composers often develop their own approaches to address this issue. For instance, in my score Book of Mirrors (2001), I rounded calculated frequencies to the nearest eighth-tone (1/8) and only notated the pitches closest to traditional semitones, selected during a custom sieve filtering process while preparing the score.
Expanding the system to 24 or even 48-tone equal-tempered tuning allows for more pitch options but still involves approximating frequencies into a notational grid (i.e. 1/4 and 1/8 tones respectively). Composers may opt to round frequency calculations to the nearest semitone, as seen in the first half of my Roseherte (2008), transitioning to quarter-tone notation later in the score. Such compromises rely on musicians’ ability to tune by ear, while fostering a sense of freedom and intuitive connection to the score. Electronic sounds synthesized with precise frequencies served as a “guide” for the musicians during rehearsals and performances, serving a dual role: shaping the music and informing performers on intuitively adjusting pitch intonation.
A more precise method of notation can be observed in my scores nadir (2014) and the honeycomb conjecture (2015), where frequencies are approximated to the nearest semitone, but the deviation in cents from the notated pitch is indicated above each note, offering a more detailed understanding of pitch accuracy to the musician.
The electronic sounds that are present in many of my compositions are synthesized using the unapproximated frequencies and provide a means of reference for the musician during rehearsal and performance. In this way the role of the electronic sounds is two-fold, both as constituent to the music as well as a reference base for the performer: the electronic sounds shape the overall music and inform the instrumentalist how to adjust the intonation of the written pitches.
EG: In your music there is a great interest in the perceptive element. In your opinion, is it possible to derive illusory sounds for the listener from microtonality?
RH: The previous response already hinted at my profound connection to (and fascination with) perception. It’s perception that defines our humanity, bridging the gap between our physical existence and the surrounding world. So my interests as a composer naturally extend into the realms of natural science and psychology, especially focusing on acoustics and psychoacoustics.
Human perception is essentially an ongoing process of making sense of the input provided by our senses. For instance, when we hear various frequencies, we process these auditory signals by merging them into cohesive sounds. For example, we understand when different frequencies originate from one single sound source and can approximate its location. This process seems straightforward because it happens so swiftly. For example, the instant recognition of a lion’s roar can propel us into action. But, in truth, our brains can execute incredibly sophisticated operations based on just a brief auditory sample. I find this utterly intriguing. We possess the capability to auditively map out our surroundings and differentiate among various sound sources. And it is also our auditory system, refined over thousands of years, that enables us to appreciate music. In fact, we engage in aural interpretation as an ongoing stream of anticipation, and surprise.
It is this stream of anticipation and surprise that composers, myself included, seek to craft and evoke. For example, our hearing automatically creates sum and difference tones when it encounters two frequencies simultaneously (a mechanism used to determine whether or not the tones are part of the same sound spectrum, i.e. a single sound source). As a composer, I like to create these sum and difference tones myself and directly present them to the listener. This leads to a consonant sound, which feels very natural, because the two tones are now part of a harmonically consistent spectrum. The resulting spectrum, for instance, can then be distorted over the course of a piece through frequency modulation or ring modulation. The listener experiences different degrees of dissonance but still senses the intrinsic resonance of the spectrum and still can hear the fundamental tone. This could be called an auditory illusion, but in fact, it’s an expression of how ingeniously our perception works. As a composer, I am inspired by this and actively employ these kind of phenomena related to perception in my music.
EG: Have you ever used (or thought about using) Fibonacci ratios in composing?
RH: As a composer I am deeply interested in the intersection of music, mathematics, and science. Drawn to their inherent beauty and the natural balance they bring to musical structures, I have indeed found inspiration in mathematical concepts, including the Fibonacci series (and fractal structures based on Fibonacci ratios). This sequence of numbers, in which all consecutive pairs are in accordance with the golden section, mirrors patterns observed in natural growth, thereby infusing compositions with an organic sense of development and balanced elegance. By integrating these ratios (and various fractal formations) into aspects like timing and rhythm, as well as pitch and harmony, I seek to create a music that resonates deeply with nature and our perception.
While the use of Fibonacci ratios and other mathematical models is a part of my compositional toolbox, it’s important to note that these techniques are always in service of the artistic vision rather than an end in themselves. The challenge and joy of composition lie in balancing these mathematical structures with intuition, emotion, and expressive depth. In this way, the Fibonacci sequence, among other mathematical concepts, offers a pathway to explore the inherent beauty and complexity of sound.
EG: Like most of your compositions, Bron is also a great piece. For Bron you used pure tunings. Can you tell us how you worked with them and how the musicians approached this knowledge?
RH: Thank you. As mentioned before, as a composer I work in a continuum of frequencies, simply because this is in accordance with the acoustics and psychoacoustics of sound, as informed by our knowledge of sound in physics and psychology. For bron, I aligned the music closely with the natural harmonic series, seeking to create a rich and resonant harmonic language. Again, I calculated the frequencies and other musical parameters in OpenMusic. For the orchestral score, I chose to approximate the found frequencies to the nearest semitone. Working with musicians during the rehearsal of this piece, then, involved a detailed process of tuning and intonation adjustment to capture the exact frequencies. This required a deep sensitivity to the subtle nuances of sound. The musicians approached this challenge with openness and curiosity, adapting their playing to achieve their own tuning and exploring the unique sonic possibilities that emerged from this approach.
EG: In one of your interviews for Bron, I was struck by the phrase: “…I have come to understand better why certain sounds work well in music. With this I want to develop new harmonies and above all new structures for harmonious sequences…” (my translation from Dutch – 2). Can you tell us briefly where the secret is?
RH: What I refer to as the ‘secret’ is really the ongoing synthesis of my learnings about sound with my imaginative explorations as a composer. The ‘secret’, to use the term loosely, is more of an evolving discovery process rather than a fixed, hidden formula. It embodies a form of intuitive understanding that has matured through a lifelong pursuit of learning. It centers on an openness to the myriad possibilities that emerge at the confluence of acoustic science and artistic creativity, perpetually propelled by the inquiry, “What if?” This approach doesn’t claim to have all the answers but is instead a humble acknowledgment of music’s vast potential to surprise and delight for those who listen to it. In essence, my work would like to be an invitation to listen anew, to find beauty and meaning in the interplay of order and innovation, and to experience the familiar and the unknown as part of a shared musical journey.
The ‘secret’ essentially is about wanting to develop new harmonies and structures in a deep engagement with the nature of sound and a willingness to question and expand upon traditional compositional practices. By closely examining why certain sounds and their combinations resonate more strongly, I have endeavored to transcend traditional limits. In creating bron (source or spring in English), my fascination with the harmonic series —also recognized as Just Intonation—played a central role in shaping the piece’s harmonic landscape. The pitches rely on natural harmonic frequencies (i.e. fundamentals and their whole number multiples) rather than the equal temperament system. The resulting materials offer a richness and depth of sound.
For this orchestral work I chose to not notate microtones, for obvious reasons of limited rehearsal time. Instead I approximated the frequencies to the nearest semitone, so the parts and score immediately do communicate with the performers in they way they are used to. I then invited the performers to built the harmonies – some of which contain more than forty separate voices – while listening closely and trying to tune their pitches harmoniously, while achieving a maximum of resonance quality within the resulting harmony. This was, actually, also a fun thing to do for the performers. The players Radio Philharmonic Orchestra seemed to really enjoy the process. And, needless to say, so did I. One could really hear and feel this sense of joy during the performance.
EG: I really like the relationship you have established with architecture: in your works Curvices, Ways of Space, and The Listening House, that all came about in collaboration with an architect and designers. What were the greatest satisfactions you gained from these experiences?
RH: Working alongside architects and designers has been immensely rewarding. These collaborations have pushed me to think beyond the conventional boundaries of music concerts and concert halls. In particular, it has given me the opportunity to explore how music, technology, and spaces may interact to create immersive experiences. The joy comes from seeing how architectural elements can influence and become an integral part of the composition, enhancing the audience’s engagement and perception of the music. These collaborations have allowed me to experiment with the physical and acoustic properties of space, creating works that are not just heard but experienced bodily. It’s a fascinating realm, one that continues to inspire and challenge me, providing new ways to engage listeners in a multi-sensory exploration of music. Seeing audiences respond is deeply satisfying, as it suggests new possibilities for emotional and intellectual engagement with music. Curvices (based on the poetry book Curvices and Musicles) and Luisterhuis (English: The Listening House) are two examples of projects that embody the integration of music, poetry, and digital technology, further exploring the relationship between music and architecture:
Curvices is an app-driven sound and poetry installation designed to transform the way we experience a specific location—be it a park, a cityscape, or any architectural environment—through walking. The core of the project is a mobile application that uses GPS technology to trigger audio as the listener moves through the space. The soundscape includes my compositions, electronic music, and recitations of my poetry, all of which are thematically and acoustically tailored to complement the physical and emotional contours of the environment. The inspiration behind Curvices was to dissolve the boundaries between the listener and the surrounding space, allowing for a deeply personal exploration of both the physical and sonic landscapes. The piece becomes a kind of musical and poetic mapping that changes with each performance, shaped by the listener’s path and pace.
Luisterhuis is a conceptual piece that similarly integrates music, poetry, and space but focuses more on the idea of a physical structure designed for experiencing sound. This project conceptualizes a rather abstracted dolls’ house with built-in loudspeakers, specifically crafted for the visitor to engage with my soundscapes, where the architecture itself is an intrinsic part of the listening experience. Each room in the dolls’ house possesses its own soundscape, that changes when approaching the particular room it symbolizes.
These projects are about extending the boundaries of traditional concert experiences, offering audiences the opportunity to engage with music in a more interactive, exploratory manner. In these works, I aim to challenge the conventional roles of composer, performer, and listener, encouraging a dynamic and participatory form of musical and poetic experience. The use of technology—whether through GPS mapping in Curvices or sensors in Luisterhuis—serves as a bridge between the art and its audience, allowing for a more flexible, personalized interaction with the work. Ultimately, both projects reflect my belief in the power of music and poetry to transform spaces—both physical and metaphorical—into places of discovery, reflection, and connection. By inviting listeners to navigate and interact with these works on their own terms, I hope to foster a deeper, more intimate relationship between music, space, and the individual.
EG: I know that your new CDs should be released within the year. Can you tell us briefly what they will contain?
RH: The upcoming CDs will showcase the breadth of recent explorations. The CDs that are to be released later this year are dreams of airs and infinity stairs. The first CD contains my music and poetry cycle dreams of airs, performed by the Belgian Spectra Ensemble with conductor Filip Rathé and soprano Lore Binon. The second CD contains the afore-mentioned article 6 [waves] (2013), article 7 [ways to climb a mountain] (2012), and article 8 [infinity] (2014), solo works with electronic sounds for electric guitar, bass clarinet, and flute respectively, as well as the trio infinity stairs (2014), when the three solo works are performed. In addition, article 5 [dolphin, curved time] (2008) for solo soprano, and article 10 [prismes] (2021) for solo cello, will be part it. The CDs highlight my recent compositions, featuring works that exemplify my engagement with spectral techniques, and the use of electronic sounds with instrumental scores.
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Notes:
(1) A couple of essays that are particularly interesting for composers are:
–Contemporary Compositional Techniques and OpenMusic, published by Delatour France in English, with contributions also by Bob Gilmore, essays on the main spectralists and an interview with Murail;
–Spectralisms in the Music of Rozalie Hirs and Their Points of Departure in Research and Innovation, a publication by Oxford Academic, currently available only for academic institutions, which will be part of a huge book-study on spectralism entitled The Oxford Handbook of Spectral Music.
(2) From the interview with Dimitri van der Werf, New Music Now, December 2023.
