Speech transmitting diaphragm and grid for breathing mask

摘要

An outer clamp ring (2) has a female thread and screws onto an inner ring (3) with a male thread. Diaphragms (5,9) with perforations (18,19) partially block the passage through each ring and protect a thin flexible membrane (15) between the discs. The edge of the membrane (4) is trapped between the threads. Projections (20) on the two rings engage the membrane and tighten it as the inner ring is screwed into the outer ring.