KTM noise limit sound monitors By Ben Purvis
There's been an explosion of noise-monitoring technology recently, which means that authorities around the world have a growing armoury of equipment to keep tabs on loud vehicles and hand out fines to offenders. That shouldn't be a problem, except that there's a growing catalogue of cases where standard motorcycles are too loud for local limits despite complying with construction and use rules.
The fact is that while bikes must pass a barrage of tests to gain type approval, testing engine and exhaust noise in a variety of circumstances, it's still possible for them to be substantially louder outside those parameters.
Now KTM is working on a solution that approaches the emergence of local noise monitoring and rules in the same way that we already approach speed limits by giving the rider an indication of how loud the bike is at any specific moment via an on-dash display.
If noise limits are going to be tightened only in specific areas, like city centres or areas of natural beauty where loud bikes might be seen as a nuisance, it makes sense to approach noise in the same way that we already deal with speed, modulating it to suit the conditions and the rules in each area.
KTM's system is illustrated in a new patent application that shows how an array of transducers around the bike - either microphones or piezo sensors - feed back to the on-board computer. The noise levels picked up by those sensors can be used to judge the absolute volume of the bike, which is displayed on the dash either numerically as a decibel readout or simply as a 'too loud' warning light when it goes over a preset level.
The patent suggests riders could activate the preset when entering quieter areas where there's a tight noise restriction, or simply keep an eye on the decibel reading in the same way as we're already responsible for controlling our own speed and staying within limits.
