Making a Bullroarer — The Oldest Instrument You Swing Through the Air

A bullroarer is just a flat slat of wood on a cord. Whirl it around your head and it spins on the twisting cord, chops the air, and makes a deep pulsing ROAR. It is one of the oldest instruments humans have — used across the world for tens of thousands of years.

Cut a flat blade about a hand-span long and two fingers wide — a long thin oval or leaf shape, a few millimetres thick. Bigger, heavier blades roar deeper; small light ones buzz higher.

Carve both long edges down to a slant, like a knife or an aeroplane wing — one edge sloping up, the other down. These bevels are what make the blade spin as it slices the air. Sand it smooth.

Pierce one small hole near ONE end of the blade, well in from the tip so it will not split out.

Tie a strong cord about an arm's length through the hole. A short handle loop at the far end gives you something safe to hold.

SAFETY FIRST: go outside to a wide open space with NO people, animals or windows within two cord-lengths — a swinging bullroarer hits hard. Whirl it in a big circle around your head. It roars; whirl faster for a higher pitch, slower for a lower one.

Almost every instrument makes sound by shaking a trapped column of air (a flute), a string, a skin or a solid bar. The bullroarer does something rarer: it is a FREE aerophone — it stirs the open air directly, with no tube and no enclosed cavity at all. Here is the mechanism. As you whirl the blade, the cord winds and unwinds, so the blade spins rapidly about its own long axis; because its edges are bevelled like a propeller, the spinning aerofoil sheds a train of little swirling vortices off its edges, and each shed vortex is a pressure pulse — a puff of sound. The blade spins many times a second, so those puffs blur into a continuous rolling ROAR whose pitch rises the faster the blade spins. On top of that, swinging the whole thing around your head sweeps the sound source toward you and away again, so the roar swells and fades in a wah-wah wobble — the same Doppler effect you hear in a passing siren. This is close kin to the aeroacoustic 'edge tone' that voices every flute (a jet of air fluttering past an edge), which is why the bullroarer sits in the aerophone family alongside the bone flute and the panpipe — but where those tune a captive air column with finger holes or pipe lengths, the bullroarer simply throws sound into the open sky. Found from Aboriginal Australia to Stone-Age Europe to the Americas, it is among the very oldest human instruments, and almost everywhere it was treated as a sacred voice.