The Authority shall thereupon cause a notice specifying the day on which the Authority will proceed to determine the objection, and directing their appearance before the Authority on that day, to be served on the following persons, namely:—

   (a)  the applicant;

   (b)  all persons interested in the objection, except such (if any) of them as have consented without protest to receive payment of the compensation awarded; and

   (c)  if the objection is in regard to the area of the land or to the amount of the compensation, the Collector.