Shiver down the backbone

‘Just relax your fingers. Stick them on the fingerboard around the seventh fret. Bang!’ Jimi Hendrix comes to Radio Three.

Even though the stations are slowly morphing into each other, with Michael Morpurgo being read on Radio Two (rather well by Robson Green, apart from his ascent into comically high falsetto every time he has to take on the voice of a woman) and Charles Hazlewood playing Britten alongside Curtis Mayfield also on Two, it’s still a bit of a shock on a Saturday night on Three to stumble across that unmistakable blaze of sound. Had I swapped stations by mistake? But there it is again. Dong, dong chang dong, dong chang: the chords at the beginning of ‘Purple Haze’. This is rock, so of course no one can agree on what this dissonant blend of notes should be called — the H Chord, the Purple Haze Chord, the Seven Sharp Nine Chord, the Augmented Seventh Chord — but they all accept that its effect is unbeatable, that it’s the quintessential rock chord.

So what exactly does that mix of E, G sharp, D and G natural sound like? And why does it now so inextricably belong to Hendrix? Rock’s DNA: Portrait of a Guitar Chord (produced by Alan Hall) tried to find out in a programme that segued from blasts of the chord to musicians talking about what it’s like to play and why it always has such an impact. ‘It makes you feel like a rock god …It’s a real up yours …It kind of tells a story like nothing else does.’

Bobbie Gentry, Radiohead, Steppenwolf …once you know what it sounds like you can hear that H Chord everywhere. And each time it has the same electrifying effect: a shiver up the spine, an immediate tensing of the body.