GIPSA Lab, CNRS, Grenoble INP, 11 Rue des Mathématiques, Domaine Universitaire, 38402 Saint Martin d'Héres, France.
J Acoust Soc Am. 2012 Mar;131(3):1999-2010. doi: 10.1121/1.3672688.
An inversion scheme is proposed, relying upon the inversion of the noise of a moving ship measured on a single distant hydrophone. The spectrogram of the measurements exhibits striations which depend on waveguide parameters. The periodic behavior of striations versus range are used to estimate the differences of radial wavenumber between couples of propagative modes at a given frequency. These wavenumber differences are stacked for several frequencies to form the relative dispersion curves. Such relative dispersion curves can be synthesized using a propagation model feeded with a bottom geoacoustic model. Inversion is performed by looking for the bottom properties that optimize the fit between measured and predicted relative dispersion curves. The inversion scheme is tested on simulated data. The conclusions are twofold: (1) a minimum 6 dB signal to noise ratio is required to obtained an unbiased estimate of compressional sound speed in the bottom with a 3 m s(-1) standard deviation; however, even with low signal to noise ratio, the estimation error remains bounded and (2) in the case of a multi-layer bottom, the scheme produces a single depth-average compressional sound speed. The inversion scheme is applied on experimental data. The results are fully consistent with a core sample measured around the receiving hydrophone.
提出了一种反演方案，该方案依赖于在单个远程水听器上测量的移动船舶噪声的反演。测量的声谱图显示出条纹，条纹取决于波导参数。条纹相对于距离的周期性行为用于估计给定频率下传播模式对径向波数的差异。这些波数差在多个频率下进行堆叠，以形成相对频散曲线。这些相对频散曲线可以使用传播模型合成，该模型使用底部地球声学模型进行馈送。反演通过寻找最佳的底部特性来优化测量和预测的相对频散曲线之间的拟合。反演方案在模拟数据上进行了测试。结论有两点：（1）需要至少 6dB 的信噪比才能以 3m/s 的标准偏差获得底部压缩声速的无偏估计；但是，即使信噪比低，估计误差仍然有界；（2）在多层底部的情况下，该方案会产生单个深度平均压缩声速。该反演方案应用于实验数据。结果与在接收水听器周围测量的岩心样本完全一致。
