Unless otherwise ordered and noticed, hearings shall be held as a part of the regular meetings of the Council. The hearings shall be de novo in that an independent reexamination of the matter shall be made. The Council may decide the matter upon the record or may take additional evidence. Any oral or documentary evidence may be received, but the Mayor shall exclude irrelevant, immaterial, or unduly repetitious evidence. It shall not be a ground for objection that the evidence is hearsay or secondary, but the Council's decision shall be made upon substantial evidence. (1962 Code § 1-6.203)