Council shall hold a public hearing on each resolution or ordinance enacting, amending, or repealing zoning or building regulations, and shall give 30 days' public notice of the time and place thereof in the manner established under Section 4.12 of the Charter.
   Except as provided below, written notice of the hearing shall also be mailed by the Clerk of Council, by first class mail, at least 20 days before the date of the public hearing, to the owners of the property within and contiguous to the area which is the subject of the proposed resolution or ordinance. Such written notices shall be mailed to the addresses of such owners appearing on the current tax duplicate of the County.
   Where the subject of such public hearing involves 300 or more of the property owners of the Municipality, then written notice to owners of the hearing, as provided in the preceding paragraph, shall not be required.