Serendipitous Effects of Masking Noise upon Sensations Produced by the Dentist's Drill

Abstract

The observations to be reported were made in a dentist's chair. Part of the sensory stimulation was generated by the dentist and his dental equipment, particulary his drill, during the course of routine dental operations. Part was generated by apparatus consisting of random noise generator, low-pass filter, stereophonic tape playback, patient-operated faders and attenuators, power amplifiers, and earphones. The initial observations concerned masking of the drilling noise. Low-pass random noise sufficiently intense to mask the drilling noise completely turned out not to be itself objectionable. Not only the sound of the drill, but also much of the massive complex of tension, anxiety, and pain was drowned in the masking noise. One patient {JCRL) made subjective observations, during a single drilling, alternately with and without the masking noise. During the masking noise, there was only a “small, thin sensation of pain.” When the masking noise was off, the noise and vibration of the drill accrued to the core pain and made it seem larger and more noxious. Further tests were made with music, and with music and noise in combination. Music is less effective than noise as a masker, but it is very effective in inducing relaxation. The combination of music and noise, alternating under the patient's control, appears to provide a practicable dental analgesia. Observations on more than 170 patients will be described, and applications outside the field of dentistry will be mentioned.

Effect of simultaneous auditory stimulation on vibrotactile thresholds

“…Again, the effects are small and tend to diminish in time. Gardner and Licklider (1959) demonstrated that intense acoustic stimulation acted as an analgesic agent in dental surgery, but Licklider (1961) cautioned that these were clinical observations and recognized the difficulty of achieving dramatic effects in the laboratory. Howitt and Stricker (1966), using an auditory masker whose onset preceded the signal by 1 sec, were unable to show an increase in pain thresholds or tolerance to electrostimulation of the tooth pulp.…”