Jackhammer Chisel Noise Control

A robust chisel damper for quieting a jackhammer is presented. The noise produced from a jackhammer chisel is dominated by the ringing of the chisel moil resulting from impacts of the internal hammer against the end of the chisel producing airborne radiation of the transverse bending and longitudinal modes. A model steel chisel moil point was constructed with geometric properties similar to a jackhammer chisel and designed so as to not fail during severe acceleration impacts from the reciprocating hammer. Anechoic tests of the maximum overall unweighted sound pressure level for the undamped chisel due to a longitudinal impact was 86.8 dB linear (re. to 20 μ Pa) at 1 meter with the strongest ring tone at 1.37 kHz and harmonics; the overall sound pressure level for the damped chisel with identical axial impacts was reduced by 16.5 dB to 70.3 dB with severe reduction of 40 dB of the dominant chisel ring tone, and the harmonics.