as said above, 7 doesn't sound too high, but its a basic microphone in the engine so it will pick up other noises
ive seen a knock level of 200 on my hand controller before, obviously thats bad of course.
60 will turn on the engine check light, so apexi decided that a knock of 60 or higher is bad enough to throw the engine check light on
its also possible there isnt enough knock, ie knocking is too low, which means the engine isn't tuned hard enough