| 摘要 |
A device to be used in phonometric measurements on telephone equipment, simulating a human ear, has a generally disk-shaped body with an annular ridge encompassing a frustoconical central recess serving as a wide-open entrance cavity. The body has several internal cavities communicating with the recess through restricted channels, namely a pair of major cavities resonant at low audio frequencies, an intermediate cavity resonant in the middle audio range, and a minor cavity resonant at high audio frequencies, the last-mentioned cavity having the shape of a narrow cylinder extending generally along the body axis. A microphone, connected to a measuring circuit, rises from the bottom of the recess to substantially the top level of the surrounding ridge to pick up incoming sounds at that level. |
