From his early childhood, Stephen Cornford recalls one particular school music lesson. He grew up in Highbury, just near the Arsenal stadium. In this one particular music lesson, Cornford recalls the teacher holding down a note deep at the bass end of the piano. Raise your hand, she instructed the pupils, when you can no longer hear the note sounding. As the pitch began to decay, small hands soon started shooting up. But silently Cornford was adamant. "No no, I can still hear it. I can really still hear it. It was a very long time. I was the last person to put my hand up."

It's a memory that has stayed with him, at least partly for the eagerness of his peers to conform to what they perceived was expected of them. "The expectation was, I've got to put my hand up. So people started putting their hands up," Cornford reflects. "But I thought, that's not the task." At the same time, the teacher demonstrated that day something about the afterlife of sounds, the resonances that live on from sound media long after they have apparently ceased operation. As Cornford said to me of the task set by his music teacher all those years ago: "You've got to listen."

Stephen Cornford likes, he admits, "to tinker". A sound artist and sculptor, a great deal of his practice concerns finding new life for dead media. "I'm working in a studio where there's lots of used electronic equipment lying around," he explains, "and part of the process is getting this and plugging it into that even though it should never be plugged into that." Typical Cornford projects might involve finding unexpected sounds in the mechanisms within CD players or old TVs.

In this sense, he is right at home as a member of Oxford Brookes University's Sonic Art Research Unit, where ongoing projects examine the use of found materials in art practice and the Consumer Waste record label, curated by Cornford with Samuel Rodgers, takes a particular interest in "people who are working with things that have been discarded - or would have been discarded if they weren't working with them".

The roots of his current approach go back to the late 90s. At that time, Cornford was leading a kind of double life - sculpture student at the Slade by day, DJing at underground raves and squat parties around London at night time. One particular performance at the Slade saw the artist effectively tarring and feathering himself like some medieval brigand. "I covered myself in tarmac from head to toe," he elaborates, "and then crawled inside a mattress and covered myself in this foam which stuck to the tar. It was pretty unpleasant." He pauses for a moment before correcting himself: "It was very unpleasant."

Around the same time, he started making music on a computer. "I hated the process," he admits, speaking recently via Skype. "I was pushing sounds around on a screen going, no, I don't like that so I'll move it three millimetres to the right. I thought, this is not in any way sculpture. I was trying to find a way of making sound or making music which was more akin to making sculpture. Then at some point I stopped saying, this is the sculpture I'm making and this is the music I'm making, and they just became one thing that I didn't draw a line between."

I first became aware of Cornford's work at a warehouse gallery in Hackney Wick, back in 2009. At the time, he was a serial trespasser on the still-under-construction London Olympics site. Declaring himself 'artist in residence' to that building site on the marshlands of the Lee Valley, he started to build up a sound portrait of the site using whatever detritus he found there.

His show at the Elevator Gallery that year involved two electric guitars and a bass mounted on motors with a variety of old bicycle parts and found construction materials such that they would spin on their axis, building up a whirling susurrus of sound as they rotated entirely without human intervention. For the opening night, a drummer came in to play along, completing the classic rock four-piece. Other pieces from the same time involved doing similar things with violins, pianos and so forth.

Recalling that period of his work, Cornford says: "I used to do a lot of work with instruments that was related to disrupting a classical tradition. Working with instruments but deliberately not playing them or deliberately having some other way of playing them as a bit of a two-finger towards the idea of composition and virtuosity." That same critique comes out in the title of a much more recent work. Referencing the classical string quartet, his CRT Quartet takes four old cathode ray tube TVs and creates a feedback loop between the images on the screen and the sound coming from the speakers.

The project started, he explains, as a "big accident. I bought some Doepfer synth modules and I was intending to drive DC motors with them, sending an LFO to the DC motor to twitch in vaguely controllable ways. I'd been playing around with TVs for a separate piece and I wondered what would happen if I sent the LFO into the TV. I plugged it into the TV and it was wonderful white noise patterns that related directly to the sound. So then I just kept playing with it and playing with it."

This way of working is a common aspect of his approach. "It's an accident - but an accident that comes about through deliberately trying to misuse things." Such a modus operandi is motivated from two directions: "Partly I see it as political. It's a kind of protest. It's saying I don't want to use things in the way the instruction manual tells me to use them, so that we're not completely suckered into the consumer-industrial model where we are given things and we use them in the way that we are told to by the people who manufactured them and then we're told that they're no good anymore and we throw them away and buy the next thing which is supposed to do that for us. But then also, you know, in a more childlike way, it's kind of playing with things. I like to mess about with stuff and see if I can twist them a bit."

"I think a lot of what I'm doing is giving machines agency, or seeing if they have an agency of their own." This, he accepts is "dangerous territory - I don't want to anthropomorphise them completely. Cute little tape machine is a bit of an annoying response." What it comes down to is a kind of "existential point of view: what are they? What do they do of their own accord when we're not trying to control them too much? What materiality do they have? How do they work? And how does their operation start to govern our use of them? You can find out a lot through working with the specificity of machines which we know instinctively but which we've never really thought about."

Head to Stephen Cornford's website here. Stephen, Jason Zeh and Ben Gwilliam's What were Tapes tour begins next week, heading to Bang the Bore at Cafe Kino, Bristol on June 17, Cafe OTO, London, 18, Westhill Hall, Brighton, 19, and Fundevogel, Todmorden, 20; for full details and tickets, head here