| 摘要 |
A method and device for detecting opening of a passage in a bodily cavity, the device including an electric signal source; a first transducer for converting an electric signal from the electric signal source into an acoustic signal; a second transducer for reception of the acoustic signal; and where the first and the second transducer are placed on respective opposite sides of the obstruction in the cavity. In the method an acoustic signal is supplied at one side of the obstruction and received at the other side of the obstruction, when the passage is open. |
