It goes without saying that there have been huge changes in studio technology over the last forty years – but what's interesting is how at every stage in this evolution there has been a need to improvise with whatever the current technology provides. Pink Floyd's music has always made use of all kinds of what might be called ‘environmental sounds’, and EMI had their own enormous library of sound effects on tape as well as the commercially available vinyl discs of sound effects. But often the quality simply wasn't good enough to take them off a vinyl record, and sometimes the specific sounds required weren't available, so we'd have to find our own ways to make or find the sounds. Examples would be the sound of footsteps for the 1973 album Dark Side of the Moon, recorded in the Abbey Road echo chamber; or the clock sounds, for which Alan Parsons, the engineer on that album, went out to a clock shop – in Islington I seem to remember – and recorded a lot of chiming and ticking and so on. Those were relatively straightforward, but when Roger Waters and I were doing the track ‘Money’, we ended up assembling a bunch of coins and drilling holes in them so that they could be dangled on strings in order to achieve the right sort of coin-jingling sound.