| 摘要 |
<p>A selective filtering sound transmission device comprising an end piece provided with a valve and a drilled hole and designed to fit into the external auditory canal, said end piece being formed by making a mould of the auditory canal and producing a countermould. Said hole (2) includes a tube (3) which opens into the space (7) left between the end piece (1) and the eardrum (4), the outer end of said tube being extended by an acoustic valve (8) which is partially or wholely inserted in a holder (6) housed in the end piece (1) and which defines at least one resonance cavity (8').</p> |
