[Black Lotus]

Seems to me detonation is an uncontrolled combustion event anywhere in the combustion cycle. The flame front for the normal event triggers an uncontrolled "explosion" of unburned gasses elsewhere in the combustion chamber. The two pressure waves collide and the piston gets a wallop equivalent to hitting it with a hammer.
Look for melted aluminum on the spark plugs, and pitting on the pistons--or a hole melted into it.
Don't ask me how I know about the aluminum on the spark plugs' ceramic, and pitting...
Also, couldn't hear it because of the exhaust noise from my mighty '65 Corvair.

Now we have Knock Sensors that sense the specific vibrations of detonation and preignition and retard the ignition timing, and/or cut boost levels, to save the engine.