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LF ultrasonic penetration tester for materials of high sound attenuation characteristics - uses conical collimating unit of compact porous foam material with through bore in central axis aligned with reception test head
Trichterloser Lautsprecher mit hohler Membrane, die aus einem kegelfoermigen und einem kegelstumpffoermigen Teil besteht, deren gleiche Grundflaechen fest miteinander verbunden sind