What you are describing is NOT a hearing loss related problem - it is called "occlusion".
It is related to a hearing aid user having an occluded (blocked) ear canal due to the presence of the hearing aid plastics.
Low frequency sounds of the speaker's own voice and/or eating of food (<500 Hz) travel via bone conduction and enter the cavity between the hearing aid and eardrum. These trapped LF sounds cannot escape and so can sound very loud to the hearing aid user.
Note that this problem only happens if the hearing aid user has GOOD hearing at the low frequencies!
If the user has a hearing loss at low frequencies then this occlusion effect is NOT noticed.
This is simply a problem of hearing aid usage, not hearing loss.
Some hearing aids (or earmoulds) have holes ("vents") drilled through them to let this LF sound escape in an attempt to reduce the problem.
However this can then increase this risk of feedback whistle.
Modern "open fitting" hearing aids such as the GN Resound Air are specially designed to overcome this problem.
Perhaps increasing the gain of < 500Hz frequencies via an equaliser would create the effect you seek?
(Creating the effect of hearing loss is a different problem)