Olasek - Most of the time, by most pilot.
We are not taking about what happens "most" of the time but when signals/alerts are missed, clearly there are numerous examples when aural signals were completely missed by the crew (either the signal was missed or lack of sound was missed too), in this particular case the crew "missed" (or deemed as normal) that they had to pull the yoke with 80- lbs of force. If they missed that makes you wonder about their state of mind and whether sound would do any good. Also, just from the human factor point of view it is bad design to make pilots rely too much on all kinds of warning "signals" - signals themselves may fail for independent reasons (like this buzzer in the Detroit crash) and pilot not hearing any sound may think everything is OK and dangerous complacency sets in.
Agreed.
I prefer the "low airspeed" aural warning in addition to the stick shaker. As you intimated, this crew ignored many, many other cues. Who knows if another aural alert would have saved them from themselves.