PURPOSE: To realize the reduction of noise in a high frequency sound range generating from blow-off holes by a method wherein blow-off passages of air beyond the blow-off holes of a vibrating pen are provided in a sound absorbing wall.

CONSTITUTION: In a pressurizing chamber 22 partitioned in the case 6 of a vibrating pen, pressurized air is introduced from air source and then blown off through blow-off holes 23 in blow-off passages in a sound absorbing wall 3. In this case, though noise is generated when the air is emitted from the blow-off hole 23, the noise is converted into heat in the blow-off passages and then absorbed. Since the acoustic-to-thermal conversion efficiency by the sound absorbing wall 3 becomes higher at a high frequency sound range, the inner diameter (d) of the blow-off hole 23 is made smaller. Thus, the noise in a high frequency sound range is generated so as to realize higher sound arresting effect. Further, by making the inner diameter D of discharge holes 31 larger (than (d)) in the blow-off passages, the speed of the air emitted is lowered, resulting in suppressing the generation of noise at the release to the air.