The hearing is open to public observation, except for the parts that the presiding officer states to be closed under a provision of law expressly authorizing closure or under a protective order entered by the presiding officer. A party may apply for a protective order to close part of a hearing. The party making the request should state the reasons for making the application to the presiding officer. If the other party opposes the request, a written response to the request shall be made within ten days of the request to the presiding officer. The presiding officer shall determine which, if any, parts of the proceeding shall be closed and state the reasons therefore in writing within twenty days of receiving the request.