Previous studies have shown that different pathological knee joints produce unique acoustical characteristics.In‐vitro simulation of acoustical signature was attempted using bovine knee joints placed in a “flexing” machine. Mechanical destruction was induced on the articular cartilage surface, and the noise produced during rubbing was picked up by a sensitive condensermicrophone, amplified, recorded, and converted into digital form. A computer program was written to perform various statistical analysis. Cartilage surface roughness was measured with a profilometer and a spatial waveform roughness distribution curve was plotted out. Preliminary results show that the unique acoustical characteristics of the various knee‐joint diseases can be simulated fairly well with this technique. This study therefore provides a rough diagnostic indication of the degree of roughness of the various types of knee‐joint diseases. [Work supported by NIH.] © 1976 Acoustical Society of America