VARIABLE-TEMPERATURE SOUND SPEED MEASUREMENT BASED ON FAST FOURIER TRANSFORM INDUCED BY VARIABLE FREQUENCY

Using a self-developed audible sound wave research comprehensive experimental platform, sound velocity measurements under normal and variable temperature conditions were studied based on the variable frequency Fast Fourier Transform (FFT). The measurement results were compared with the traditional method of measuring sound velocity at a fixed frequency. The results showed that the error of this method and the traditional method of measuring sound velocity at a fixed frequency was less than 1.00% at normal temperature. However, the error of the traditional method fluctuated with the increase of the fixed frequency. The error of the measurement method based on variable frequency FFT decreased with the increase of the distance between the transmitter and receiver. The results obtained by both measurement methods were in good agreement with the theoretical values, indicating that the measurement results based on this platform had high accuracy and the equipment operated stably and reliably. Under variable temperature conditions, the sound velocity increased linearly with the increase of temperature. The obtained results were in good agreement with the theoretical values, with a maximum error of 2.09%. This further verified the reliability and convenience of the measurement method based on variable frequency FFT, providing good support for subsequent measurements of sound velocity under different pressures and different media conditions based on this platform.