N.Y. Comp. Codes R. & Regs. tit. 19 § 211.38
Each timekeeper shall have and maintain an accurate stop-watch or stop-clock, and also a whistle or buzzer or other auditory device, which shall be approved by the Commission before each contest or exhibition to which the timekeeper has been appointed. The timekeeper shall sit outside the ring platform and close to the gong, bell or other approved auditory device. The timekeeper shall keep the time of each round and intermission by means of an accurate stop-watch or stop clock. He or she shall sound the gong, bell or other approved auditory device to begin and to end each round by striking it with a metal hammer or by other means approved by the Commission. The timekeeper or alternate referee shall count for knockdowns by striking the floor of the ring or a suitable wooden striking board with a substantially constructed hammer or mallet or other means approved by the Commission. The timekeeper shall signal by striking the floor of the ring or a suitable wooden striking board with a substantially constructed hammer or mallet or other means approved by the Commission to indicate when only ten seconds remains in a round. The timekeeper shall also signal by whistle or other means approved by the Commission when ten seconds remain before the beginning of a round, and at such signal all seconds shall leave the ring immediately and shall remove all stools and equipment from the ring immediately. Except as above, the timekeeper shall give no signal or other information during a contest or exhibition.
N.Y. Comp. Codes R. & Regs. Tit. 19 § 211.38