21 Jul 09
The intercom system which enables drivers and co-drivers to communicate with one another above the noise of a World Rally Car is the subject of the latest WRC explained technical feature here on wrc.com.
This season we're bringing you a series of video features, produced in conjunction with a WRC expert, which cover some of the areas mentioned in the wrc.com glossary in more detail.
Stobart VK M-Sport Ford driver Matthew Wilson explains how the intercom system works in this exclusive video feature. You'll find more details below:
Whether driving on a liaison section or a special stage, the cockpit of a World Rally Car is an extremely noisy place to be. With the production car's noise deadening material stripped away to save weight, all of the mechanical and road noise is transmitted straight into the cockpit.
The whining of the engine, turbo charger, straight-cut gearbox and three differentials is bad enough, but add in the noise of gravel hitting the wheel arches like shotgun pellets and the constant drone of the exhaust system and you have a truly deafening environment.
Amid all of this chaos, however, it's vital the rally driver and co-driver are able to maintain concentration and have a clear two-way conversation. This is where the car intercom comes in.
How it actually works
According to Wilson, the driver / co-driver intercom system is one of the most vital parts fitted to his Ford Focus World Rally Car. "The noise inside the car can be incredible - especially on gravel rallies," he says. "Without it I couldn't hear a word my co-driver Scott said - even if he was shouting at the top of his voice."
The system consists of a small control box, usually located between the drivers' seats, and two different types of headsets. This control unit manages audio inputs and output volume and is connected to the headsets using cables which run to a connection socket strapped to each driver's safety harness.
The headsets both consist of noise attenuating earphones, which seal snugly around the ear to cut out most background noise, and a fast-adjusting, noise-cancelling microphone mounted on a boom so it can be positioned in front of the mouth.
"The kit is basically the same for the two types of headsets, but we use them at different times," explains Wilson. "The first is mounted inside our crash helmets, which we use on the stages, while the second is just the earphones and the microphone, which we use on road sections and during the recce. Because of the extra noise on the stages, the in-helmet unit is set to be louder and clearer than the headset only version, but apart from that they are they same."
Once out of a stage drivers unplug the intercom cable from its socket, remove their crash helmets and store them in net baskets hung from the roll cage behind their seats. The intercom headsets, also usually stored in the nets, are then put on and plugged in for the road sections.