Public notice shall be given to the applicant, the Zoning Officer, such other persons as the Township Board of Supervisors shall designate by ordinance and to any person who has made timely request for the same. Written notices shall be given at such time and in such manner as shall be prescribed by ordinance or, in the absence of ordinance provision, by rules of the Board. In addition to the written notice provided herein, written notice of said hearing shall be conspicuously posted on the affected tract of land at least one week prior to the hearing. The Zoning Hearing Board may mail notice of the hearing to the owner of every lot on the same street within 500 feet of the lot or building in question and of every lot not on the same street within 200 feet of said lot or building; provided, that failure to give notice, either in part or in full, as stated by this subsection, shall not invalidate any action by the Zoning Hearing Board.