Infrasound in The Effect

Anyone who has seen Lucy Prebble’s gripping new play The Effect may be curious to know more about the peculiar sonic undercurrent which is present at certain points in the drama. As this has been mentioned in a few reviews, I thought I should say a little more about it. The strange sensation you’re experiencing is infrasound – an extreme bass sound which plays through the air and vibrates the seats, walls and other structures in the Cottesloe Theatre.

Infrasonic notes are pitched so deep, they’re on the cusp of your perception. Descending in pitch from the bottom end of the piano into the infrasonic range is like stepping into the sonic abyss. Audible sound slips away as you drop further into the bass range and you’re left with a purely tactile sensation –  a sound you feel rather than hear. I’ve been experimenting with infrasound since around 2003, when I laced a concert in the Purcell Room with infrasonic pedal notes. I became curious about the musical effects of infrasound when I realised that some of the biggest pipes in cathedral organs were creating sounds so deep, they were in the infrasonic range. Although they’re inaudible – in theory at least – these sounds seem to have some peculiar physical and psychological effects. Some organ players throw these infrasonic bass notes into the mix to create a feeling of awe. Stranger still, in the 1990s, a physicist named Vic Tandy presented some tentative evidence that infrasound may be present at some ostensibly haunted sites. This, rather than anything supernatural, may make you feel spooked as it creates a sense of unease and the sensation of an invisible presence in the room – an impression that’s heightened if it gently shakes sheets of paper, upholstery, doors and other loose objects around you.  The infrasound may come from a mundane source – Tandy had some odd experiences when his workroom was swamped with infrasound from a faulty ceiling fan. But it still has an unfamiliar and unsettling effect.

An early acoustic test at NPL (Crown Copyright)

Knowing how peculiar infrasound can be, when I was asked to  compose an electronic score for The Effect, I jumped at the chance to make the most of the subwoofers in the Cottesloe Theatre and deploy some infrasound. Working closely with sound designer Christopher Shutt, I designed an infrasonic track that’s convincingly shaped and ramps in volume, in and out of the action, to create the desired effect. I prototyped and shaped the infrasonic track with Max/Msp.

The infrasound in this show is around 16-18Hz in frequency – just over an octave below the bottom end of the piano. Unlike the bass notes you might hear on a big nightclub sound system, the infrasound in the show is a pure note (a sinusoid) with no audible, higher-pitched harmonics. That helps to create a strange sensation – you’re aware of its presence but can’t quite pinpoint it as sound.

A couple of years ago, I worked with theatre company Punchdrunk on a new special effect which mixed infrasound with another technology (still under wraps). We deployed this curiosity in It Felt Like a Kiss, Adam Curtis’ immersive, walk-through documentary for The Manchester International Festival (2010).

My first foray into the world of infrasonics, back in 2003, was in collaboration with The National Physical Laboratory and others, including psychologists Richard Wiseman and Ciaran O’Keeffe.  It was funded by the Sciart Consortium (see ‘Soundless Music’). I’d love the opportunity to research infrasound formally. I want to pin down and quantify  its effects – something we were only able to do tentatively in our formative research project.