Any hearing which the commission has power to hold may be held before any one or more of the commissioners; however, the commissioner or commissioners must have been authorized by the commission to hold the hearing. Each hearing before a commissioner or commissioners must be considered the hearing of the commission. Any determination, ruling, or order of a commissioner or commissioners, upon a hearing held by him or them, must not become effective until due notice has been given to the commission and the determination, ruling, or order has been approved and confirmed by at least a quorum of the commission and ordered to be filed in its office. Upon such confirmation and order, the determination, ruling, or order shall be the determination, ruling, or order of the commission.