Several studies dealing with the perception of musical timbre have found significant correlations between acoustical parameters of sounds and their subjective dimensions. Using the conclusions of some of these studies, a calculation method of the perceptual distance between two sounds has been developed. Initially, four parameters are considered: spectral centroid, irregularity of the spectral envelope, attack time, and degree of variation of the spectral envelope over time. For each of these, a transformation factor between the physical axis and the corresponding subjective dimension is obtained by linear regression. After a normalization of the data, the final distance values between sounds is given by a linear combination weighted by the four transformation factors. Since this model is based on numerical results derived from experiments that mostly used synthesized sounds, the application to a database of recorded musical instrument sounds needs a strong validation procedure. This procedure involves the adjustment of the coefficients of the first four parameters as well as the eventual introduction of new ones to attain a perceptually relevant distance between two musical sounds.