A system for adapting a hearing aid to a user includes a unit generating an image of the user's ear together with a model of the hearing aid, wherein the model of the hearing aid in-situ includes a physical model of the hearing aid inserted in the user's ear prior to generating the image. The system also generates a mesh based on the image, calculates acoustic response to a simulated acoustic signal in the mesh, calculates a frequency response curve for a fixed position in the mesh, and identifies an optimal position of a microphone of the hearing aid in-situ from the acoustic response. They system also includes a comparator configured to compare the frequency response curve for the fixed position in the mesh with a maximum frequency response curve for the mesh stored by the system.