Asking someone to sit in a location that is less likely to induce feedback can also be ill received; people have genuine and legitimate seating preferences. Few people want to be sentenced to the "hard of hearing" section. They should be able to sit anywhere in the sanctuary seating area they wish.
But, they need to understand that they won't hear as well as they could if they would not allow their pride to get in the way.
This needs to be presented to the individual in the right way so that they understand that you want them to be able to hear the performance or presentation the best that they possibly can.
For a single output ALD system time delay can only be accomplished to it's best in one area.
This is not to say don't accommodate but rather that accommodation has limits.
I have spent a lot of time studying how to better help those who are hearing impaired through better applications of sound systems and the use of ALD's. Unfortunately it comes down to each persons hearing loss being different. The best help for partial loss is achieved through the proper application of DSP based hearing aids and nothing that we do as system designers or as mixing engineers can compensate for the deficiencies of more than one individuals specific loss at any given time.
We can make it louder, within limits, and we can time align the signal arrival, but only within a small area. Specific EQ, compression, etc. may help some with hearing loss but actually make it worse for others.
The best option for extreme loss is a system that will work in conjunction with the individuals well tuned hearing aid or that seals out all outside sound either by being sealed circumaural headphones or by fitting into the ear canal like an ear bud.
Individuals with cochlear implants often plug the ALD receiver directly into their implant with a cord, no acoustic transducer
Lee Buckalew
Pro Sound Advice, Inc.