| Abstrakt: |
An improved sound retrieval system and more accurate analysis technique were developed to extract distinguishing acoustical signatures of sound emitted by normal and pathological knee joints during active movements. Background noise was minimized using the principle of 'noise cancellation' with a double microphone-differential amplifier setup. Two identical sensitive condenser microphones and an FM recorder with flat responses in the audio range were used. The knee noise was found to be transient in nature and recordings were made on magnetic tape 'loops' for 'real time' analysis. Waveform, spectral, and statistical (correlation and probability) analyses were performed. Preliminary studies of 30 knee recordings covering normal, rheumatoid arthritic, degenerative knees, and knees with Reiter's syndrome showed that their respective waveforms, spectral patterns, and statistical properties are, on the average, unique and proved to be a promising nondestructive diagnostic tool for early detection of the type and extent of knee joint damage. [ABSTRACT FROM AUTHOR] |
