A method of calculating the speed of sound in a nonparallel layered model is presented. A focussed ultrasound source and receiver are used to locate the angle and position of an incident pulse and the reflected pulses at the surface of the model. Triangulation is used to calculate the speed of sound in the first layer and points on the first interface for a number of source positions and angles. For subsequent layers, ray tracing is used to eliminate the effect of the overlying layers. A computer simulation in which images of the speed of sound are reconstructed from data generated by ray tracing through two models is presented. Ways in which this method could be implemented are proposed.
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