Clash of the reggae titans: An extraordinary global music contest will set pulses racing

It's sound clash time again. Strictly for aficionados of reggae sound system culture, it's the musical equivalent of a special forces assault course, where the midnight 'til dawn damage inflicted by the heaviest bass bins – and the blaring horns and screeching whistles of the crowd – leaves ear drums ringing and calf muscles aching. It's also a test of mental agility, an A-level examination in recognising tunes.

But as systems (DJ collectives with giant record boxes) from around the globe prepare to descend on London's Brixton O2 Academy on Saturday night and compete to play the hardest to get specially recorded dubplates, there will be thousands of fans in attendance who wouldn't miss it for the world. The music will be Jamaican in heritage but the systems hail from Japan (Barrier Free), Italy (One Love High Powa), America (Blunt Possee), Kenya (Shashamane International) and Birmingham (Luv Injection). The Caribbean island that invented sound system culture in the mid-Fifties with the open air record-playing battles between musical entrepreneurs Duke Reid and Coxsone Dodd, will be represented in Brixton by Bodyguard and Bass Odyssey, the mightiest systems from the rural districts.

This is reggae at its most thrilling, played in an environment that turns music into a sporting contest, and one with a complicated set of rules. Sounds, which traditionally have their own amplifiers and speakers, play for "rounds" of half-an-hour, and then 15 minutes, scoring for ecstatic crowd responses (known as "forwards") and being penalised for playing an inappropriate artist in a given segment. Failing sounds are "locked off" at the instruction of the audience, until the remaining two fight for the trophy, playing "one for one" their 10 most precious dubplates. It's quite a science.

Sadly, the UK's sound systems are in hiatus, while "clash" is a thriving culture across Japan, Germany and Italy, where huge events take place throughout the summer along the Adriatic coast.

What is it with these former Axis countries and the music of Jamaica? I remember like yesterday the scene outside the Sanctuary nightclub, Milton Keynes, in March 1994, when more than 6,000 arrived for probably the most-anticipated clash ever staged in Britain. A senior Thames Valley police officer, his horse rearing up, was trying to keep order as a mass of bodies ebbed and flowed against glass doors that threatened to buckle and shatter.

I found myself standing alongside Tippa Irie, a famous MC with the competing Saxon sound system and one-time star of Top of the Pops with hits such as "Hello Darling". He seemed as bemused by the chaos as I was.

Vaulting a glass barrier and passing through the camouflage-attired security staff as they fought hand to hand with gatecrashers only added to the sense of anticipation. Sometime around 5am Saxon won the epic clash, aided by the support of hordes of followers from their south London heartland. King Addies, their great rival system from Brooklyn complained that their equipment had been sabotaged (a familiar storyline in the drama of sound clash). The end of the "one for one" was a coup de grâce, the Saxon selectors, lining up the classic "No, No, No" by Dawn Penn and playing it through some 30 speaker boxes. Thank you and goodnight. Penn's old tune then emerged as the soundtrack of a television commercial.

The pleasure of walking home in daylight, discussing the intricacies of the contest, the skill of the "selectors" and their acquisition of hard-to-get dubplates – "Was that really Prince Buster?" – will always keep the aficionados coming back for future sound clashes, gruelling though the ordeal might be.