Does meditation increase sensitivity to these stimuli?
In abhidhamma, mind can does just an object, focus, per a arising. And there are over than a trillion mind arise per a second.
On non meditation day, the practitioner has too much several objects per second. So, practitioner's sense perceptions are over sensitivity more than his ability can notice all objects on his sense perceptions.
But on meditation day, the practitioner has just only one main object, main focus, per a meditation, maybe through an hour or a day. So, it is easier for him to notice unusual object, that is out of meditation's object and appear on his sense perceptions.
If so, how, and what is the purpose of this with regard to meditation practice?
If it's possible, the practitioner should move to the better place, to avoid to waste the time on non meditation's object, because mind can have just one object per arising. Or if it's not possible, ignore them, don't focus on them. Because the practitioner must has just meditation's object, focus. So the practitioner must take his mind back to meditation's object, such as breath of ānāpānassati meditation.
For an advance insight meditation practitioner, balava-vipassanā, he has a powerful ability to meditate in every situation. But the beginners practitioners can't act like him, because their mind's focus can easily stolen by non meditation's object more than his powerful skillful meditation's object.