| 摘要 |
<p>An apparatus for generating in particular low-frequency sound, comprising a drive unit (10) and an open resonator (11) connected thereto. Said driving unit (10) comprises a housing with a movable member (14) opening and closing an aperture (13) provided in said housing and opening in said resonator (11). The member (14) is operated by means of compressed air whose actuation of said member (14) is controlled by means of a valve (21) activated by electrical pulses from a current source, the frequency of said pulses being manually or automatically controllable. For the removal of soot from furnaces, several apparatuses of this type may be coupled in parallel to a common current source, such that they operate in phase, and a considerable sound amplification is achieved.</p> |
