A device generates coefficient data of an estimating equation for converting a first information signal to a second information signal. The device performs decimation on a teacher signal to generate a student signal and acquires plural training data items from the teacher signal corresponding to the second information signal and the student signal corresponding to the first information signal. For each training data item, a similarity determination unit acquires the similarity of the student signal with respect to the first information signal corresponding to a second information signal at a position of interest. Coefficient seed data, which are coefficient data of a generation equation including the similarity as a parameter, are determined using the training data items and the similarity. A coefficient data computing unit determines, based on the generation equation, coefficient data of the estimating equation using the coefficient seed data and a similarity value indicating the highest similarity.