Once or twice I was at the "Barber Pole" and got the usual overspeed warning, (Clacker) but no buffet at M.90.
The Lear 23 & 24 I recall from long ago had some sort of siren instead of a clacker! I remember that loud siren going off one flight and not immediately associating it with an overspeed warning. I was spooked by it and initially reached for my O2 mask as I had thought it was a pressurization problem.