@mikepa, I'm not sure of a "best" distance, but it would seem that a little trial and error is needed. The closer you are to the transmitter, the better. You also have to consider the angle. It would seem that being perpendicular to the countertop is best, but how the telecoil is mounted in the hearing aid also plays a role. I attended an HLAA convention several years ago. All rooms are looped. I sat next to a person that had recently been implanted with a CI. She had to put her head down (away from the presenter) in order to hear from the loop. I think they botched the orientation of the telecoil in her processor.
Tony in Michigan