进行翻译：计算梯度时依然可以基于声学假设。因为梯度的大小只取决于反传的残差源中波形扰动的大小波场的幅值是系数项对计算结果的影响可以被迭代步长所矫正。

When calculating gradients, it is still possible to base them on the acoustic assumption. This is because the size of the gradient depends only on the magnitude of the waveform perturbation in the backward residual source, while the amplitude of the wavefield is a coefficient that can be corrected by the iterative step size in the calculation.