| 摘要 |
<p>The device comprises a microphone (2) and a speaker (3) arranged one on top of the other with the microphone pointing downwards at a horizontal supporting surface (10) and the speaker pointing upwards and mounted in a cavity (6) which has a vertical axis and forms an enclosed space defined by a housing (7) placed above the microphone, said microphone being nondirectional and coaxial with the cavity. The microphone (2) is set into a tubular sleeve (15) having a closed upper portion (16) and an open lower portion (17), and is centred on the axis of the housing, whereby a hollow recess is defined for receiving the microphone which is directed at a smooth, rigid reflector plate (26) arranged facing the open lower portion (17) of the sleeve (15).</p> |
