you can hear detonation when reving the car up and listening to the motor closely. You may want to get a tune if you are worried about it, or take it to a place so they can listen for it and/or check your air fuel ratio.
My car is N/A with only the regular bolt ons and I was detonating hard with 91 octane.. so i got a dyno tune and everything is fixed up and I'm set to run on 91.
Usually it's heard when the car is under load. Get on the freeway put it fourth, floor it and take it up to redline. If at anytime your engine sounds like something starts rattling , or knocking, or pinging, that's probably detonation. Immediately get off the gas.
If you are not allready using it then you should try a higher octane gas. If your car still detnonates on pump gas then you should start troubleshooting. Plugs, 02 sensors, air filter, ask a shop.
If you added various mods to your car without a dyno tune it may be time to have it done.