Classification of temporomandibular joint sounds based upon their reduced interference distribution

Abstract

Temporomandibular joint (TMJ) sounds were recorded in 98 orthodontic retention patients, mean age 19 +/- 8.6 (s.d.) years, by interview, auscultation and electronic recording. Sounds were found by auscultation in 41% and by interview in 32% of the subjects, more often in females than in males (P < 0.05). A new method for time-frequency analysis, the reduced interference distribution (RID), was used to classify the electronic sound recordings into five subclasses, RID types 1-5, based upon location and number of their energy peaks. RID types 1-3 had a few energy peaks close in time. RID types 4-5, typical of subjects with crepitation, had multiple energy peaks occurring close in time for a period of 20-300 ms. RID type 1, found in 45% of the subjects, typical of patients with clicking, had its dominant energy peak located in a frequency range < 600 Hz and was significantly more common in the female than in the male subjects (P < 0.01). RID type 2, found in 68% of the subjects, with the dominant peak in the range 600-1200 Hz, and RID type 3, found in 38% of the subjects, with the peak in the frequency range > 1200 Hz, were found to have a similar gender distribution. RID type 4, found in 49% of the subjects, had the energy peaks distributed in the frequency range < 600 Hz. RID type 5, found in 43% of the subjects, more often in females than in males (P < 0.05), had the peaks distributed over the whole frequency range from about 30 Hz up to about 3000 Hz. In conclusion, a more detailed classification could be made of the TMJ sounds by displaying the RIDs than by auscultation. This suggests that RID classification methods may provide a means for differentiating sounds indicating different types of pathology.

Physical mechanisms involved in the genesis of temporomandibular joint sounds

“…Most TMJ clicks have a frequency in the order of 300 Hz which would imply a bubble with a diameter of 1 cm. However, cavitation may explain the short duration, high frequency sounds described by Widmalm et al . (1996b) .…”

“…Watt (1981) defined four types of sounds which were clicks or crepitus each of which could be either hard or soft. Widmalm, Williams & Adams (1996a) and Widmalm et al . (1996b) proposed five types of sounds based on the appearance of time–frequency plots of individual sounds.…”

Comparison of TMJ vibration frequencies under different joint conditions

“…rubbing together and without proper lubrication. [95][96][97][98][99][100][101][102][103][104] From a practical standpoint, due to the non-linear sensitivity function of the human ear, low frequencies are easier to detect with palpation, but higher frequencies are far more audible. 105 While it is certainly possible for a clinician to learn to hear and/or palpate for TMJ vibrations, these techniques are difficult to teach and quite hard to learn.…”

Amplitude and frequency spectrum of temporomandibular joint sounds from subjects with and without other signs/symptoms of temporomandibular disorders

“…A significant number of studies have tried to differentiate the sounds based upon characteristics such as amplitude and frequency (Findlay & Kilpatrick, 1960; Ouellette, 1974; Drum & Litt, 1987; Oster et al ., 1984; Gay & Bertolami, 1987; Heffez & Blaustein, 1986; Hutta et al ., 1987; Gay et al ., 1987; Gay & Bertolami, 1988). A general agreement has, however, not been reached and some authors claim that the joint sounds do not have a significant energy content in the frequency range above approximately 1000 Hz (Wabeke et al ., 1992; Ishigaki, Bessette & Maruyama, 1993) whereas others have found substantial amounts of energy in the frequency range well above 1000 Hz (Widmalm et al ., 1992; Yoshida et al ., 1994; Widmalm et al ., 1996; Widmalm, Williams & Adams, 1996). It therefore seems important to use a recording device that allows recording of frequencies both below and above 1000 Hz.…”