DECIBEL, Perth’s pre-eminent “new music” adventure squad, are back in record form – with their first release of original compositions since 2012’s Stasis Ecstatic. Tuned Darker take its title from Louise Glück’s poem “October,” and the lines: “the light has changed / middle C is tuned darker now.” Decibel’s sounds have always seemed erred towards darkness to my ears, and they have never shied from toying with benchmarks like Middle C, so perhaps this title represents more of a general tendency than a progression in their approach. Either way, it’s aptly poetic and enigmatic for an album that fits those same descriptors. It’s an album that explores the very nature of sound and, in doing so, continuously evokes visual worlds. But it also eschews easy and conventional modes of doing so – things like sampling from familiar sound-sources, or layering on descriptive titles, lyrics or album art. Indeed, the cover – a beautiful abstract photograph by Traianos Pakioufakis – offers no figurative imagery to cling onto. What it does do is seductively map out a subtle and textured gradient between light and dark, which is a pretty good summary of the music that lies ahead.

Cat Hope’s “The Lowest Drawer” is a piece that seeks to answer a question, which is: what happens when you perform live acoustic notes and then translate them to “pure” electronic sine waves? Moreover, what happens when you keep that process going in an overlapping fashion? Given that Decibel’s long-standing project is to probe the acoustic/electronic intersection, this is a concise illustration, a neat introduction to the record. Of course, the answer to the piece’s conceptual “question” depends on countless variables, and The Lowest Drawer is a self-consciously specific iteration of the “answer.” It pursues Hope’s personal fascination with low-end pitch, getting increasingly deep and rumbling as it plays out, culminating in a fearsome 13-pitch chord that rattles your foundations. But what’s most interesting is hearing the live instruments – cello, bass flute, bass clarinet – retrace over their sine-wave siblings, like watching a body pass by its strangely more-perfect shadow. The process foregrounds the fallibility of the live acoustic instrument, and similarly its performer, which has a particular charm. Meanwhile the slight discrepancies between live and electronic notes produce a discernable “beating” between frequencies, giving the interplay an seasick, visceral quality. You could argue that the piece is too scientific, that it privileges the illustration of sonic phenomena over musical expression. But – notwithstanding the false dichotomy thus presupposed – there’s plenty of flavour here, an evocative quality even if it’s incidental. There’s a symbiosis here between the art and the science, one adding heft to the delivery of the other.

Stuart James’ “n dimension” (2013) is rooted in ideas well beyond my purview: its inspiration and structure derive from topology, infinity, chaos, fractals. I can’t tell you anything illuminating about those things but then again, the piece in itself is not didactic, nor sealed off for the edified few; liner notes notwithstanding, it offers itself as a raw experience to be had. And it’s a remarkably beautiful mist of shifting, intermingling atonal drones and textures, punctuated by unhinged percussion and seemingly free-floating rhythms. Electronics flutter and swarm like insects in the dusk, ominous string clusters hang heavy in the air, woodwind burbles and gasps. The piece feels neither still (as drone/ambient works often can) nor set on a clear trajectory, instead jostling and folding within its own aural and conceptual parameters. When you reach its final passage, you have not necessarily moved from your position in the landscape, but you’ve seen it turn inside-out around you, revealing itself from countless viewpoints like a shimmering Cubist marshland.

Track 3, which lasts for 31 seconds, is literally Silence – I say literally because it is called Silence and there is no data in the audio waveform but of course it is not silence in practice. In practice it might be the hum and crackling surface noise of your turntable/stereo setup, or the otherwise imperceptible hiss of your headphones. For me right now it’s the muffled coughs and murmurs of other people in the library from which I write; the patter of fingers on computer keyboards; the gentle exhalation of the air conditioner and the whirr of a nearby photocopier. Whether this is conscious nod to John Cage’s 4”33 (I know Decibel are big on Cage – and you can’t really not be in this field) or merely a decision to delay the onset of the coming piece, the impact is the same. You become aware of the present moment, and your surroundings, and the impossibility of actual silence, via a gesture of omission.

And now it’s Lindsay Vickery’s “Night Fragments.” The title derives from the process in which its main source material was created: the Belgian Surrealist poet Francilon Daniels used to write down thoughts experienced in not-quite-asleep states which were later published as Journaux Intimes; these become the libretto for Vickery’s experimental opera. There are some truly spectacular lines among Daniels’ hypnagogic scribblings, like

“a broken wing beating in the dark”

“it is a redwolf lying on the embers of a fire,” or

“one by one / the nurse places keys in my mouth / the doctor says / you’ll have to swallow them / my body slowly filling with keys”

Interestingly, and impressively, Vickery’s composition resists the temptation to make these phrases “scan” per conventional lyrics; they get dissected and reassembled; they follow unpredictable melodies generated by computers; they jump erratically between Caitlin Cassidy’s operatic mezzo-soprano and her Aussie-accented spoken word. In these ways they resist passive reception, simultaneously throwing you off their scent and drawing you in to listen more deliberately. This all occurs via a backdrop of phantasmagorical composition rendered by alto-flute, clarinet, cello, keyboard and electronics. Pseudo-jazzy patchworks of phasing phrases reminiscent of Serialism butt up against simmering, impressionistic lulls. Bursts of symphonic dissonance jag you like sleep-jerks. It feels both impassioned and yet, paradoxically, unemotional, generated as inevitably and matter-of-factly as a thunderstorm. Clocking in at almost 17 minutes, it’s not something you can fully digest in one listen, at least not without your intensity of focus varying, but that’s ok. I’m reminded of Delia Derbyshire and Barry Bermange’s creepy long-form opus “The Dreams” in which interviews detailing somnambulant visions are spliced over haunting music concrete collages. Drawn out, intricate, oblique but with moments of chilling clarity: this is the sort of thing which prompts plenty of repeat listens, albeit destined to accompany your more peculiar moods.

While the frivolous part of me sometimes yearns for Decibel to truly leap out of their comfort zone – to unshackle themselves from the Western Art Music aesthetic and engage, for example, with other “new” forms to be found in contemporary pop music and the “pop” underground – the truth is they’ve already got broad horizons and are shrewd in setting the scope of any given project. “Tuned Darker” evades any obvious genre designation, even if “Night Fragments” is plainly informed by opera. It’s an album which, rather than expanding the sound ever-outwards, digs deeper into the details. And it’s all the richer for it.