Sound and vision blog

25 August 2015

Surface Tension: a conversation with Rob St John part 1

Rob St John is a writer, musician and artist who recently collaborated with the waterways charity Thames21 on Surface Tension, an audiovisual project highlighting the pollution issues currently facing the River Lea. Here Rob discusses the project and how he set about exploring this vast body of water.

Last summer you were approached by Ben Fenton from Thames21's Love the Lea project to produce a piece of work that explores pollution issues currently facing the River Lea. The River Lea is a pretty substantial stretch of water, running from Hertfordshire to east London and carving a route through a range of different habitats. With a brief like this, where on earth did you start?

With an OS map and some walking boots! Thames21 generally work on waterways within the M25, so the geographical spread was narrowed down a little, although that said I did walk further upstream, way past the motorway, mostly to get a better idea of how the valley changes as the river flows (or doesn’t as I increasingly found) south. Lea Valley has plenty of decent footpaths, so walking the river wasn’t really a problem; instead the challenge was to track different channels of the Lea, particularly as it splits off and out around Enfield. In the end, I walked from up past Cheshunt down to where the Lea meets the Thames at Trinity Wharf, and back again, over the course of a few weekends in the late summer of last year.


You made a range of field recordings during that summer. Did you have a clear idea of what you wanted to record or did you approach it with a completely open mind?

It was largely exploratory: after the first recording walk I pared down my recording kit quite substantially, relying largely on a simple field recorder and OKM binaural microphones. There’s something really enjoyable about being able to be so mobile when recording; to stop and quickly set up and capture an emergent or interesting sound. Binaural recording feels very attuned to your body – obviously in the way the microphones sit in your ears – but also in the ways it picks up your footsteps, the sound of you swallowing or your stomach rumbling…(an issue on some of the longer walks).  

There’s a wider conceptual thing here about how you approach field recording, I think. For me, binaural recording’s inherently mobile and bodily characteristics – coupled with the incredible, spatial recordings that it produces – make it an appealing approach to me. I’d much rather be led by my feet and ears in trying to catch traces of the soundscape, rather than setting up masses of kit in an effort to record a specific sound or set of sounds in the highest possible clarity and fidelity. Again, I suppose, this depends on what you want to do with the recordings. In this project (and in general) I didn’t record for reference sound libraries or similar, but rather as a means of providing a palette of natural (and non-natural) sound to produce, alter and generally tinker with in the final piece of sound and music.

Can you tell us about the types of recordings you made?

The binaural recordings were great for picking up the familiar sounds of the Lea Valley: boat communities, cyclists, parakeets, overground trains, aeroplanes, coots and moorhens, footballers on Hackney Marsh, dredgers in the estuary, riverside bars and cafes spilling people out onto the towpath. But in a way that’s more than representational of these individual sounds; binaural recordings are great for picking up wider resonances, overlaps and blurrings of different sounds, often anonymous and shorn of their source, prompting an uncertainty of what in fact you’re hearing.  

Enfield Coot family

I loved the way that parakeet calls would flit around car alarms; the way the rumble of traffic seemed to compensate for the lack of sound from a still river; and how coot calls would reverberate around echoing dry docks along with the clatter of machinery and hammers: an often unintended (and fascinating) blurring of the natural and non-natural, man-made and self-willed through sound.  And often there would be long, subtle drones and burrs in the recordings that I didn’t hear at the time: possibly the effect of my body acting as an antenna through to the rumbles of the ground (it’s perhaps never more evident quite how loud London is until you record there).

Parakeets over Hackney Marsh

In addition to the binaural recordings, I used two other types of microphones: hydrophones and contact mics.  Hydrophones are dropped beneath the surface of a body of water (a process that’s a bit like ‘fishing for sound’ I guess), and pick up the buzzes, scrapes and rumbles of the underwater soundscape: boat engines, insect activity, aquatic birds diving, and occasionally a sound that you cannot identify. Contact mics are stuck to various surfaces (drain pipes, walkway handrails, brick walls, sewer pipes and so on) with electrical tape, and pick up vibrations transmitted by the city (water, traffic, people, boats) conducted through various objects and surfaces.

Hydrophone in Trinity Buoy Wharf

The three techniques allowed me to collect a wide palette of sound from the Lea Valley, each transmitted and filtered in different ways: from the air, through solid objects and surfaces and from beneath the water’s surface. I wanted to let the environment lead me rather than being prescriptive in setting out to capture a specific set of sound: building an inherent sense of uncertainty, chance and serendipity into the approach. I mean, the Lea Valley soundscape (if you can be so general, scale is very important here) is constantly changing and fluid, and heard in an inherently individual and subjective way, so I thought: why try and necessarily pin it down to specific constituent parts?

The different recording techniques you used during your fieldwork allowed you to explore the Lea from both above and below the river’s surface. Underwater recordings are endlessly fascinating because they help you to eavesdrop on a world that is usually inaudible to the human ear. Could you tell us about some of the more unusual or unexpected sounds you encountered beneath the surface of the River Lea?

Listening to pondweed photosynthesise is always a hoot, particularly in the way that putting hydrophones into a seemingly ordinary, perhaps polluted, stretch of water can bring it alive: giving voice to invisible life below the water’s surface. When pondweed photosynthesises (the process of exchanging dissolved oxygen and carbon dioxide with the water), it releases streams of tiny air bubbles. When these hit the submerged hydrophones, they produce a variety of short percussive crackles and buzzes, a little like minimal electronica. Added to this, there are the sounds of various underwater insects flitting through the pondweeds, and striating their back legs in order to communicate and signal. Finally, there’s a sonic backdrop of the river itself: of boats passing with rattling hulls and whirring propellers; of mysterious and unseen swooshes that could well be passing fish.  

I ran a public engagement workshop at last year’s Thames21 Love the Lea festival last summer, where we had a number of headphones set up to listen in to the hydrophones. It was a real pleasure to get to talk about this underwater sound with dozens of people – young and old – most of whom brought different interpretations as to what they might be listening to. There’s a real creative, imaginative effect to listening to these obscured sounds in seemingly still and lifeless places.

How many recordings did you collect during that summer?  

Dozens of hours of recordings, which were then edited down to around fifty or so recordings for use in the composition and soundmap.

What other documentation did you collect?

I took photographs all along the walk, in tandem with the sound recordings. These were all taken on film, partly with a nice old 120 Zeiss Nettar camera, and partly on 35mm using pinhole cameras that I made from Lesney matchboxes. The Lesney toy factory was at Hackney Wick until relatively recently (I’m not entirely sure what it has been redeveloped as), so making new images using a cardboard ‘shell’ of Lea Valley history seemed appropriate. And whilst pinhole cameras are notoriously difficult to take decent shots on (I was using a piece of electrical tape as a shutter, and doing some mental arithmetic to calculate exposures…), some of the images that resulted were amongst my favourites. In a way I thought of the walks as ‘experimental’ or ‘creative’ geography fieldwork: tracking routes and sites in a way that echoes a field trip, but gathering information on the landscape through various creative techniques.


In the second part of this conversation, Rob explains how he transformed field recordings collected along the River Lea and scientific data into a musical composition and accompanying book.


Surface Tension can be consulted here in the British Library Reading Rooms (catalogue reference number 1SS0010348)



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