l（mm）λ1（mm）v1(m/s)10002344.989.6814.629.969.49.88358.799338.6256355.9171共振干涉法测声速567819.3424.1729.1434.19.449.669.949.92340.0666347.9918358.0786357.3581910平均39.0143.919.829.8353.75568353.0352351.5142λ2（mm）v2(m/s)相位比较法测声速09.7419.4229.1638.9648.7758.459.749.689.749.89.819.68350.8738348.7123350.8738353.0352353.3954348.7123时差法测声速0.5440.5150.48730405068.169.71349.79377.9187.61平均9.759.7351.234349.4328350.6736tl（mm）0.63400.604100.574200.459600.43700.4800.37390t-l图100908070v理论值(m/s)347.38y = -345.1x + 218.2l（mm）线性(l（mm）)6050403020100-100.350.40.450.50.550.60.65