Phonoarthrography, vibration arthrography are non-invasive methods for assessing the condition of cartilage and the knee joint as a whole based on the sounds made by the joint movement. Acoustic sensors (accelerometers, microphones) are attached to the knee to measure the knee joint noise both in control groups (young adults and elderly subjects) and in patients with knee osteoarthropathies. Different authors propose different methods for attaching sensors, documenting and analyzing the joint sounds. The identified specific features allowed distinguishing between asymptomatic knee joints and those with osteoarthropathies. Acoustic signals were recorded and processed, and their frequency characteristics were determined and classified. The classification effectiveness correlated with the existing diagnostic tests and hence phonoarthrography and vibration arthrography can be qualified as a useful diagnostic aid.