Somatosensory pain is not reliably modulated by weak acoustic stimuli

• The effect of acoustic stimuli on induced pain was investigated.
• If acoustic stimuli reduce pain, they can be used clinically
• Surprisingly, reduction in pain was not observed, only a slight increase.
• Pain in females increased after information that the stimuli increased pain.
• Findings suggest limitations for this method of pain reduction.

BackgroundPain induced by electrical stimuli has been found in previous research to be reduced by brief, weak electrical pulses, termed prepulses, presented 40 to 60 ms prior to the painful electrical stimulus.MethodsThe present experiment investigated the generality of this effect by presenting weak acoustic stimuli simultaneously with, or 80 or 1000 ms prior to, painful electric shocks. In the second half of the experimental session, each participant (N = 119) was told that the acoustic stimuli would either increase or decrease the pain induced by the electric shock, to investigate automatic and controlled cognitive processes in the modulation of pain.ResultsAcoustic stimuli presented simultaneously with painful stimulation increased pain slightly (4 mm on a 100 mm scale). Acoustic stimuli presented 80 and 1000 ms prior to painful stimuli had no effect on pain. Information that acoustic stimuli would increase pain did so in females, but only when the acoustic stimulus was presented 80 ms prior to the painful stimulus.ConclusionsThe effect of the acoustic stimuli and of information was weak. Failure to replicate previous findings of decreased pain by weak prepulses was most likely due to the sensory modality of the prepulse stimuli. It is recommended that further studies of pain modulation by brief stimulation use electrical and not acoustic prepulse stimuli.