But wait, there's more.
As mentioned above, the Low Rotor RPM warning horn is pretty much the only 'standard' audio warning horn in helicopters, from the R22 to Super Puma's. Just to give you as much information as possible, this horn warns if the revolutions of the rotor system decrease below a certain figure. It is crucial that we keep the required RPM setting other wise we run into various types of trouble. For most of us, when we hear this horn it should actualy trigger an automatic response. This response may vary in its extremes according to the type of aircraft but will follow some pretty basic rules. If we do not automatically react, the helicopter and crew will be lost.
To operate a helicopter we require an incredible number of motor skills that have been built up over time, both in flying and reacting to emergencies, so
to distract a Helicopter pilot, you will need to throw in an audio horn that he hasn't heard before (mobile phones are a good example) where his/her motor skills are not perfected through training.
Another point to add is that during emergencies it is actualy a normal thing to get rid of the audio horn whilst reacting to the problem. In a BK117 (medium sized twin engined helicopter)if we lose an engine we hear an audio worning horn, The designers have taken into account that it may be distracting so they put a small button on the cyclic to stop and reset the warning horn. But it is only a convenience thing because through training we will react anyway.
Warning horns do not restrict or distract our ability to perform a function.
cheers