Yes, that is actually possible. But unlike the hearing range which is defined within the AI perception component, the loudness (or rather how much a certain noise can be perceived outside the normal range) is defined as a property of the stimulus itself.
Within the BP_AISensoryManager blueprint, you can find a variable called InterestStimulusDataArray which is where different types of stimuli are defined. And it has a parameter named PerceptionRangeModifier (now I realize that it doesn’t convey the meaning as clearly as the term Loudness) which essentially acts as a multiplier to the AI’s default perception range.
For example, an Alarm Noise has this value set to 2.0, while the Whistle noise has it set to 1.0.
So let’s say your AI guard’s hearing range is 300 units. For the Alarm Noise, it will be perceived up to 600 units, while for a Whistle noise, it will just be heard up to the default range of 300 units. Similarly, you can set a value of say 0.5 for the footsteps so that it will have a reduced range of 150 units.
And thanks for pointing this out. I’ll add a separate tutorial this week going over the different attributes for setting up new stimuli.