Punch, Review of Crichton et al (Can Expectations Produce Symptoms…)
Dr Jerry Punch, Ph.D. Audiologist
The above-referenced study by Crichton et al. (2013) is open to criticism for its many methodological weaknesses. The most notable criticism is that their subjects were never actually exposed to infrasound. If the “studio woofer” was capable of producing a 5 Hz stimulus, they should have at least described or shown a graph of the output spectrum. Even if a true infrasound stimulus was produced by their equipment, 40 dB (presumably SPL) was not nearly sufficient to represent the level of infrasound in question by those who believe infrasound from wind turbines to be an issue. Even if a sufficient stimulus had been produced to represent wind turbine infrasound, a 10-min exposure would have been meaningless in representing the duration of exposure that is likely necessary to produce any substantial health symptoms. So the subjects were not actually exposed to any infrasound stimulation in the first place, in effect resulting in their being exposed only to two “sham” conditions.
The design itself limits the study’s external validity and thus the ability to generalize the results to other populations and situations. First, most of the individuals who have reported adverse health effects from wind turbine noise, some of whom have abandoned their homes, are not people who were adequately warned of potential health effects prior to their exposures. In fact, many individuals who report adverse health effects were advocates of wind energy prior to being exposed. Because the major premise underlying this study is that people complain of wind turbine noise based primarily on expectancies that align with prior information, the study is based on a false premise. Furthermore, the use of university students does not represent the type of subjects who represent the population apt to complain about wind turbine noise. This population is probably the least vulnerable to the effects of wind turbine noise in that none were young or old, and few if any were likely to have chronic health conditions or to be disabled.