a. The commission shall give notice of any public hearing which it is required or authorized to hold under the provisions of this chapter by publication in the City Record for at least ten days immediately prior thereto. The owner of any improvement parcel on which a landmark or a proposed landmark is situated or which is a part of a landmark site or proposed landmark site or which contains an interior landmark or proposed interior landmark, or any property which includes a scenic landmark or proposed scenic landmark shall be given notice of any public hearing relating to the designation of such proposed landmark, landmark site, interior landmark or scenic landmark, the amendment to any designation thereof or the proposed rescission of any designation or amendment thereto. Such notice may be served by the commission by registered mail addressed to the owner or owners at his or her or their last known address or addresses, as the same appear in the records of the office of the commissioner of finance or if there is no name in such records, such notice may be served by ordinary mail addressed to "Owner" at the street address of the improvement parcel or property in question. Failure by the commission to give such notices shall not invalidate or affect any proceedings pursuant to this chapter relating to such improvement parcel or property.
b. At any such public hearing, the commission shall afford a reasonable opportunity for the presentation of facts and the expression of views by those desiring to be heard, and may, in its discretion, take the testimony of witnesses and receive evidence; provided, however, that the commission, in determining any matter as to which any such hearing is held, shall not be confined to consideration of the facts, views, testimony or evidence submitted at such hearing.
d. The commission, may, in its discretion, direct that notice of any such public hearing on a request for a certificate of appropriateness, or on any plan formulated by the commission in relation thereto, be given by the applicant to such owners of property in the neighborhood of the improvement or improvement parcel to which such request relates, as the commission deems proper. When so directed, the applicant shall mail a notice of such hearing to such owners, at their last known addresses, as the same appear in the records of the office of the commissioner of finance, and shall likewise mail a notice of such hearing to persons who have filed written requests for such notice with the commission. A reasonable period of time, as prescribed by the regulations of the commission, shall be afforded the applicant for giving notice of such hearing to such owners and persons. Any failure to give or receive such notice shall not invalidate any such hearing or any determination made by the commission with respect to such request for a certificate or with respect to such plan.