At festivals around the world guitars are being played with handheld fans, contact microphones are exposing the hidden sounds of the most basic acts of friction, and turntables are being played without any records on them. I have even seen amplified glass being eaten as if it were as delicious as chocolate.

For the critic Simon Reynolds, ‘the web has extinguished the idea of a true underground; it’s too easy for anybody to find out anything now.’ But the underground is not simply about access, nor is it a mere description of the physical context of the music. The underground is essentially a practice, a cultural philosophy of music that exists outside of the mainstream. This philosophy, rather than being extinguished, has actually been invigorated through new innovations in social media, digital technology and audio culture.

What do I mean when I say ‘underground’? Historically, the underground could include 1960s psychedelic music of the US hippie counterculture, the DIY anti-corporatism of 1970s-era punk rock, the early 1990s-era of grunge rock, or 1970s and 2000s-era hip hop. Running through these styles is an emphasis on authenticity and a comparative lack of commercial appeal, but the underground I’m talking about is distinct from these. Though underground music sometimes crosses paths with popular music, its ambitions lie elsewhere. My own view is that contemporary improvisers, noise musicians and drone artists, broadly, make up the underground of today, and though the field is large and the styles broad, these musicians’ general aesthetic ambitions, combined with their comparative lack of public exposure, means that it still makes sense to consider them together as a discernible international scene.

Key to the underground philosophy is that it represents an aesthetic third space, one which eludes conventional boundaries. The ancestry of both this idea and today’s underground musical style can be traced to the eclectic activities of such sixties musicians as the Nihilist Spasm Band, Henry Flynt and Captain Beefheart (and further back again, to Dadaism). The American music journalist Ellen Willis called the Velvet Underground ‘anti-elite elitists’, expressing something of the underground’s peculiar mix of high and low cultural practices.

The underground is a guerrilla philosophy that is mostly defined in relation to the mainstream, and so could be anything at any time. Defining it in concrete, practical terms is therefore a tricky business. Frank Zappa tried: ‘The mainstream comes to you, but you have to go to the underground’. In the sixties, seventies and eighties, the fact of having to go to the underground was more clear cut, but since the advent of digital technology and the web, such a relation has become confused. MP3 blogs and file sharing websites, in addition to social networking platforms such as MySpace, have all facilitated the spread of underground music in a way that was inconceivable in the pre-internet age, when small fanzines and bootlegged tapes dominated. Everything has become available, everywhere, all of the time: culture has become flat.

Audiences no longer have to go to the underground in the same way that was required of them in the seventies, for example. As Martin Raymond, co-founder of trend forecasting company The Future Laboratory, says: ‘Trends aren’t transmitted hierarchically, as they used to be. They’re now transmitted laterally and collaboratively via the internet. You once had a series of gatekeepers in the adoption of a trend … but now it goes straight from the innovator to the mainstream.’

But the idea of the underground lives on, despite the possibility of general access. The word ‘underground’ connotes a sense of concealment, even of contraband, and this is at the heart of what still defines it as a musical philosophy. The music’s general abrasiveness repels the mainstream; the distinct willingness of the general public to either turn away or ignore its existence in the first place is what gives underground its identity, not some farcical public inability to locate it.

Cities with a rich cultural history and with firmly established public arts institutions lead the field in terms of underground scenes. Berlin, for so long cleft in two in every way imaginable, has hosted a thriving underground for decades, and particularly since reunification in 1990. Orientating around totemic minimal techno producers such as the duo behind Basic Channel, Mark Ernestus and Moritz von Oswald, and Robert Henke from Monolake, and also noise and experimental pop musicians such as Felix Kubin and Gudrun Gut, the Berlin underground scene connects back within the country’s own history to the fertile days of the Weimar Republic. But it also connects outward to other underground scenes through digital means, through festivals such as Transmediale and MaerzMusik, through venues such as Berghain, and through record shops such as Hard Wax in Kreuzberg, to name only a few of the conduits to other scenes.

London can boast a similar vitality, despite Mayor Boris Johnson’s reliably baffling recent comments lamenting the lack of a ‘counterculture’ in the city. In contrast to the largely dance-orientated music of Berlin, it is networks of improvisers and noise musicians that dominate the London underground. Building on a politically engaged tradition of underground music-making that originally developed in the sixties, musicians such as John Butcher, Sebastian Lexer, Kaffe Matthews and Eddie Prevost, among many others, deepen the cultural discourse through regular live activity at venues such as the Vortex, Boat-ting and Café OTO. Shops such as Sound 323 formerly provided the physical core for London underground musicians, but that function has largely been usurped by the aforementioned venues, in addition to the important web presence that London labels and promoters such as the leading black metal, black ambient and noise organisation Cold Spring, and disparate webzines and blogs, maintain.

In both London and Berlin, and in other important cities for underground music around the world (Tokyo comes immediately to mind), comparative economic wellbeing has made it easier to nurture underground scenes. The example of the USA, a country with perhaps the leading DIY tape and noise scene in the world, is a case in point. That DIY scene derives a kind of implicit practical support from the USA’s economic security that would be impossible in countries with less stable economies.

The institutional aspect of underground culture – its relation to the mainstream – has remained relatively unchanged over the past few decades. The impact of the web, however, has led to a fundamental shift in recent years in the nature of the underground’s very existence. The underground has largely shifted from physical meeting places such as record shops to virtual networks organised through and on the web. Underground musicians themselves are keenly aware of this, promoting their activity through their own websites, or through independent, web-focused labels, and transmitting much of their music through social media such as Soundcloud.

The web has been pivotal for the underground scene in Ireland, a country in which the institutional frameworks that buttress activity in London and Berlin simply do not exist. The country nonetheless boasts a small but fervent underground scene. An array of leading figures constitute the artistic and promotional firmament of Irish underground music. Gavin Prior, improvising noise musician, head of the Deserted Village label, and member of such bands as Wyntr Ravn and United Bible Studies, and Andrew Fogarty of weird-synth outfit Boys of Summer, of Toymonger, and head of Munitions Family label, both in Dublin; and Vicky Langan, who runs the Black Sun weirdo/outer limits music and film nights, and Paul Hegarty, of the extreme noise-group Safe and head of Dot Dot Music, both in Cork, are just some of those involved with developing a cultural alternative to the mainstream. A particularly healthy scene has developed in the past ten years or so in Cork, but Dublin, with almost ten times the population, still has the edge: artists like the Jimmy Cake and the Redneck Manifesto leading an avant-rock centred field, and Children Under Hoof, Patrick Kelleher and His Cold Dead Hands (who is notably on the Skinny Wolves label, another player in all of this) and others gigging in venues such as Anseo, Whelan’s, The Shed and the contemporary art space The Joinery, and organising the (echt-underground) ‘box socials’ on South Circular Road.

It is difficult for underground scenes to reach a degree of maturity without economic and institutional stability, but the relative health of the Irish underground scene testifies to the ability of underground cultures to flower in adverse economic or cultural circumstances, often thanks largely to the collective enthusiasm of a relatively small group of people. Similar processes can be identified in other burgeoning scenes around the world, such as that in Buenos Aires, where local musical traditions combine fruitfully with experimental dance styles and contexts, or in Beijing, where recent economic accomplishment, amongst other cultural factors, has allowed a diversity of underground musical activity to flourish. This is the case particularly with regards to the scene that has developed around the improviser and promoter Yan Jun and artists such as FM3, the former of who runs an annual underground music festival called Mini Midi, and also a famous series of improvised music weeklies, ‘Waterland Kwanyin’.

The guerrilla nature of the underground, then, persists in the digital context, and has even been invigorated by its new possibilities for international communication. The institutional and cultural richness of larger metropolitan centres such as Berlin and London has led to the development of a strong backbone of underground musicians, many of whom have been able to, by virtue of the platform given to them in their own country and through the web, connect across local boundaries with musicians and promoters from across the world. Gavin Prior’s wonderful coinage, ‘To hell or to internet’, sums up the situation for underground musicians from smaller musical centres. Economic stability can facilitate the spread of underground musical cultures, but it is not required, with the many and varied promotional and communicative possibilities of the internet proving a decisive recent factor in the nurturing of small, interpenetrating international underground scenes. The very existence of an underground culture – antagonising the mainstream, redreaming its resources for obscure ends, opening up a crucial space for experimentation and for critiquing the mainstream – in fact exemplifies the type of positive, web-mediated collective space that our new digital age has promised for so long.