Whistling arrows are arrows whose head is made up of a hollow wooden or iron 'turnip' through which several holes have been drilled. Whilst flying, the arrow emits a whistling sound that is used as a signal for directing armies in battle, to confound enemies, to transmit messages, to show one's position, to scare away animals, etc. Whistling arrows (also called signal arrows) are extensively used by Inner Asian and East Asian peoples, most notably the horse nomads and the Chinese.
The 'turnip' is fairly large (3cm~10cm in diameter) and may break upon impact, depending on its material.
Stats for The Celestial Empire:
Deer-horn- or Bone-made Whistling Arrow
Damage: 0-1 (1D2‒1)
Chance of breaking upon impact: 60%
Wooden Whistling Arrow
Damage: 1-2 (1D2)
Chance of breaking upon impact: 40%
Metal Whistling Arrow
Damage: 1-3 (1D3)
Chance of breaking upon impact: 30%