But if someone can't hear a high enough sine wave, doesn't that mean the same thing as they can't perceive the sharpness of transients with frequency components above their hearing limit? Surely if you can't hear a frequency when presented as a high-intensity constant sine wave, you're not going to hear it when mixed in with all the other frequencies for a short moment in the form of a step or impulse. Those hairs in the inner ear aren't going to activate, in other words (or their signal won't get through).