| 摘要 |
Apparatus for providing a measure of the time taken for sound to travel a predetermined distance. The apparatus comprises a transmitter electroacoustic transducer (2,46,108) for transmitting an acoustic signal, and a receiver electroacoustic transducer (3,48,108), spaced apart from the transmitter electroacoustic transducer (2,46,108), for receiving the acoustic signal transmitted by the transmitter electroacoustic transducer (2,46,108), when the apparatus is in use. The apparatus has a sound reflective surface (1,91,108) spaced apart from the receiver electroacoustic transducer (3,48,108) so that the latter also receives a reflection of the acoustic signal, and timing electrical circuitry (54) connected to the receiver electroacoustic transducer (3,48,108) which circuitry (54) serves to provide a measure of the time delay between the respective receptions by the receiver electroacoustic transducer (3,48,108) of the acoustic signal and its reflection. The invention extends to a flowmeter (10) which incorporates such apparatus and an anemometer which incorporates such apparatus. The apparatus can be adapted to measure the speed of sound. The invention extends to the corresponding methods which make use of such apparatus. |
