"Nikolaus Gerszewski sympathises with conceptual art: As an artist, my job is to decide what is art, not what is beautiful. But my work isn't quite anaesthetic either. Unlike some conceptualists - such as Joseph Kosuth - I believe that art relates to aesthetics, in the way that form is meaningful in every possible aspect.

"The sound of music is the result of an intellectual process; all that matters, is that the idea comes across as clearly as possible", he continues. "My work affines to conceptual art - the Sol LeWitt kind, not the Joseph Kosuth kind. The object itself is not symbolic of the concept; it is designed to be observed in its actual formal features."

That makes sense, I'd argue - the idea of non-aesthetic art, taking "aesthetic" in a broad sense, is a self-contradiction. "Aesthetic" is an obscure term, one that needs defining together with art. Whatever one thinks of beauty itself, a valuable artwork is one that has positive aesthetic valuations that relate to beauty. Among the positive descriptions of Gerszewski's music, I would argue, are: vibrant, coruscating, sublime.

Gerszewski is well-placed to make comparisons between visual art and music - he's an academically trained visual artist, and self-trained composer of experimental music. Born 1964 in Hamburg, he lives there and in Budapest, where he occasionally teaches. He's a member of composers collective Frog Peak Music.

What he's not a fan of is "beautification", he says. Many listeners wouldn't describe the pieces on this album as "beautiful" - there's nothing like melody or groove, and some will find them close to noise. But this is to take beauty in a narrow sense. It's what philosopher John Passmore in "The Dreariness of Aesthetics" describes as "always nice; always soothing...what the bourgeoisie pay the artist for". The "revolt against beauty" after WWI targeted this sense, and the Dada manifesto (1918) aimed to "assassinate beauty". However, beauty can be defined more broadly as the most general term of aesthetic approval. The same applies to "good", which in broad terms is the most general term of moral approval. Thus Mary Mothersill, in her book Beauty Restored (1984), draws on Plato in defining beauty as a good - an object of love, that yields pleasure.

I said that some listeners may find Gerszewski's music close to noise. But "noise" is itself ambiguous. "Noise" - and indeed "tone" - have both a purely acoustic and an intentional definition. The science of acoustics defines noise as undifferentiated sound without definite pitch, or as material whose exact frequencies are not determined, but statistical. Thus musical sounds or tones consist of regular, stable, periodic vibrations; noise consists of irregular, unstable, non-periodic vibrations. Gerszewski's music has affinities with noise in this sense. But there is also an intentional definition that parallels "weed", "pest" and "dirt" - "sound that we prefer not to hear", or perhaps "sound that is not beautiful".

Performing Cornelius Cardew's graphic score Treatise, he says, encouraged his transition from painting to music. The New York School was a great influence: "Morton Feldman's music to me is totally uncontemporary; it could have been written yesterday, or a thousand years ago, or even on another planet. That's my ideal of art." He wrote a conversation piece with Peter Ablinger - with whom he shares a fondness for the same kind of artist: Giacometti, Agnes Martin, Ad Reinhardt, to name a few - and is drawn to the severity of Bartók's string quartets. "The album Keio Line by Richard Pinas/Merzbow may have convinced me that there can be 'beauty' also in noise music," he adds.

His recent compositions follow what he calls a "procedural model", in which decisions are made prior to the notation process, and each relates to the entire work. This process gives his compositions a remarkable coherence. All three pieces on this album are for twelve strings. On "Inert Mass" (2018), the material is a four-note chord made up of minor thirds, layered in three octaves which changes in pitch, timbre, dynamics and tempo. The individual parts pulsate - they are not only shifted in time, but also layered in pitch. After twelve minutes the starting position is restored and the process repeats. It's the composer's first use of what he calls "mixer form", derived from James Tenney's "swell form" from the late 1960s, based on increasing and decreasing volume.

Transferring Tenney's swell principle to tempo, pitch and timbre creates what Gerszewski calls "a plastically mouldable sound matter", a "reification of the sound". This phenomenon has also been called "sound magma" - that is, the sound appears almost as a solid physical object - and applied to Romanian spectralists Radulescu and Dumitrescu. Gerszewski was interested in Ligeti's pioneering work with micro-chromatic clusters, notably his string ensemble piece Ramifications - his concern with "the border area where a dense polyrhythmic interference-structure turns over into plain arhythmic noise". Yet Ligeti never quite arrived at sound magma, and in fact withdrew from reified sound in his later works.

The preceding comments apply also to the other works here. "Solid Rock" (2019) builds up a fluttering chromatic noise from layers of tritone intervals, stretching over two octaves. Over its eight minutes there's no change of pitch; individual parts swell and fade, each with a time delay. On "Lining" (2019), each part involves a rotating sequence of four adjacent quarter tones at a different speed. There are changes in volume and speed ratios, and transitions from non-legato to legato and from legato to battutto, with the pitch structure remaining the same throughout its twenty-four minutes.

Each composition arises from a clear idea that the listener can grasp. That is their beauty, I'd argue - there's no need for, or possibility of, any process of beautification. They are conceptual art in the broadest sense, but vividly concrete in their sonorous properties. So they are a paradigm of musical art - for music is an art that is abstract in form, concrete in utterance."-Andy Hamilton, Durham UK.