This seems the equivalent to a definition stating that anything not signal is noise and whereupon distortion perception is defined as being the point of audibility. Fair enough.The question in the title was very simple: how do we perceive non linear distortions ?
Answer: if it's audible we perceive it as unwanted noise.
Motional feedback should be a more widespread solution if people would really like linear systems.... .I had a sigma drive system and it made some fairly low quality speakers sound like a million buck speaker system, but that tight control was so linear that i could hear the stupid music behind it and let's face it like men: we actually don't like a lot of the music we listen unless we do it on the "right setup "
Where they Philips drivers? Motional feedback is interesting, having built numerous subs, including a stereo pair using 12" drivers and another pair using 6- 8" drivers per side. The vibrato the 12's produced from an organ pedal (from the classic E. Power Biggs album) at the low end was phenomenal. Unfortunately it wasn't possible in my own listening room, rather in someone elses large loft. Although there is a drastic audible difference between feedback and non-feedback speakers the room resonances created from such extension often destroyed the advantages, hence parametric notch filters were used to diminish those resonances.
Back to the point of the thread, the feedback mechanism is one of comparing the input signal to that of the voltage fed back from the accelerometer attached to the cone. Linearity occurs when the voltage signal source is proportional to the acceleration of the speaker, concluding that from the speakers perspective the input signals are acceleration waveforms. Hence the clipping of an amplifier is different from that of a speaker hitting some displacement stopping mechanism. In other words an amplifier being clipping generates the equivalent of some fixed force on a voice coil, that for a speaker to respond requires that the speaker continue to accelerate simply from Force = Mass x Acceleration. Ultimately non-linear distortions can be generated as dominantly irreconcilable in different domains.