A sonic drill head comprising an outer housing, an isolation system, a sine generator and a spindle. The sine generator generates a linear sinusoidal vibration force through the rotation of a plurality of eccentric masses. The sine generator is configured to translate the linear sinusoidal force to the spindle in a direction corresponding to the spindle's axis of rotation. The sine generator supports the spindle within the housing such that the spindle is free to rotate about the spindle axis. The spindle is generally a hollow tube section thereby allowing the passage of drilling fluid, mud, cuttings, and/or tooling. The isolation system generally reduces the transfer of the vibration force generated by the sine generator to the outer housing, yet is able to transfer an applied thrust force from the outer housing to the sine generator.