Rotorbee, I hear what you are saying but I have flown noisy turbines for 40 years and if a pilot needs an engine out light to tell them something has gone wrong then they are not listening to their aircraft.
Listening is vital, even with noise attenuating headsets, not just for engine malfunctions but for gearboxes, hyd pumps, rattles, bangs and other noises that helicopters often make just before (or just as) they are going wrong.
Trouble is when you are 200 plus miles out to sea, every flicker of a gauge or slight noise change is easy to perceive as impending doom
The yaw is noticeable in a piston but also in a single turbine, slightly less so in a twin because the other engine is still driving.
To give you an idea of how powerful the audio sense is - the Gazelle has a particular whine as the the engine shuts down and pilots would often transmit to ATC that they were complete as they chopped the throttle on shutdown - I and many colleagues have started to lower the lever in flight just from hearing that noise in the background of a radio transmission before realising it wasn't us.
I was on a checkride in a Wessex during training so I knew emergencies would come thick and fast - I had lifted to the hover and was doing a lookout turn, heard the engine note change and called 'Engine failure, landing', much to the amusement of my instructor who had done nothing and it was just the slight change in audio cue as I turned crosswind with the cockpit doors open.