What do you mean Chase "has to consciously activate" his bionic hearing? He literally fell to the ground in Crush, Chop and Burn when the school bell rang, and again in Spike vs. Spikette when Kate used her Sonic Scream against him. I think the ability has to be "consciously activated" if Chase wants to hear normal sounds from futher distance, but extremely loud noises show that this ability is actually always active to a certain height.