Very low frequency sound (less than 20 Hz) and slow pressure changes can induce substantial movements of the eardrum, even though our hearing is very insensitive to such stimulation. Because such movements could influence the cochlear fluids, we were interested in whether Meniere's patients were especially sensitive to such sounds. One situation where infrasound levels can be high is when driving at highway speed with the car window open. We therefore asked the following questions.
Questions posed : Have any of the following ever made your symptoms better or worse?
1) Riding in a car at highway speed with the window down
2) Movie theaters or stereo systems with powerful sub-woofer systems
3) Air-flow "rumble" as in the ventilation systems of large buildings
Possible Answers to each question:
(No) ( Yes - better) ( Yes - worse) (Don't know)
Approximately half the respondents were sensitive to such factors, and of those the overwhelming majority reported that they were made worse by such activities. Although this is somewhat difficult to reconcile with the fact that self-induced eardrum movements tended to make people feel better, this is complicated by the fact that all the activities above are associated with audible noise. Since many Meniere's patients are hypersentitive to loud sounds, this may contribute to the "worse" feeling reported by these patients. Of some interest are the 13% of respondents who had found that driving with the car window open gave them some relief of their symptoms. This could be due to cochlear fluid movements induced by infrasound, but there are likely numerous other explanations. For example, some may find that the noise level was beneficial if it caused masking of their tinnitus.