On an air cooled motor with the cylinder heads not far from your ears you can hear a lot of the pinging (caused by detonation).
Richer mixtures are a known way to reduce detonation. The ICE Air causes a richer mixture on throttle transitions... which happens to be when detonation is more likely to happen. How convenient!
Higher octane fuel is more resistant to detonation, but it contains less energy. If you can run lower octane without detonation, it will usually return better mileage.
The question here is, if you don't hear any pinging, could there still be some detonation?