A method and a computer system for keystroke event notification are provided. The cylindrical assembly front portion is comprised of two levers each terminating in a hook. 9 wt % of a mineral phase containing hydroxyapatite andor \u03b2 tricalcic phosphate, and 0 to 10 wt % of water, preferably 0 to 7 wt % of water, more preferably 0 to 5 wt % of water, and even more preferably approximately 5 wt % of water. Thereby, the amplitude of the driving signal of the modulator is compensated.