Without having an indication of decibel level produced, power (in wattage) of amplifiers it would be hard to say. The potential of sustained physical damage can be hard to define without some details.
Has this loudpseaker exposure already occured?
What sort of effects are you or the affected person having now, if any?
Here is link to the topic of 'hearing damage':
I've been repeatedly exposed at a fairly close level (within 3-5 feet to fairly loud rock music, where the amp was about 200-500 watts) with no lasting hearing damage. The exposure was short and effects temporary (ringing in the ears and muffled hearing for a few hours).
I also have listened with headphones at a fairly high volume; however, that specifically is where the greatest risk is. Luckily, I received no hearing damage there. Typically, if damage occurs, it will first affect the middle and treble range, so I've been told.
If the person's exposure to high-volume, close-up exposure was one-time and for a short duration, it could be temporary. However, many prof rock musicians after long and chronic exposures to their own music and with walls of 10,000 watt Marhsall amps, have SIGNIFICANT permanant hearing damage. Check out any extended interviews with a member of the Who, etc. They've been profoundly affected. A member of my network of friends met up with Roger Daltrey and he has some trouble with hearing normal conversation.