Section 8. If the court shall enter an order establishing the right of the petitioner to take the real estate, or interest therein, described in the order for the purpose therein stated and to assess betterments as therein set forth, and any person has in his answer denied the sufficiency of his compensation or damages as estimated in the order under section three or has denied that his property will receive benefit or advantage in the amount estimated therein, the court shall appoint not more than three disinterested persons as commissioners to hear and determine the issues thus raised. The provisions of law in regard to auditors shall so far as apt apply to such hearing, and all controversies as to the amount of compensation, damages and betterments arising out of the same petition shall be referred to the same commissioners. The commissioners shall hear the parties as speedily as may be and shall thereafter file a draft report with the clerk of the court and shall send notice of such filing to the several parties. The commissioners shall not determine the compensation or damages to which any person is entitled to be greater than as alleged by him in his answer, nor less than as estimated by the board; nor shall they determine the benefit to any parcel of land to be less than as admitted by the owner in his answer nor more than as estimated by the board.