At the hearing, the report of the commissioner shall be received and protests may be made orally or in writing by any person interested in the formation of the proposed district. Any protest which pertains to the regularity or sufficiency of the proceedings shall be in writing and shall clearly set forth the irregularities and defects to which objection is made. All written protests shall be filed with the clerk of the board of supervisors on or before the time fixed for the final hearing. The hearing may be continued from time to time not exceeding 60 days.