Vibroacoustic disease (VAD) is a disease that affects the whole body. The systemic pathology is the product of excessive exposure to low-frequency noise (LFN). Occupations at high risk for VAD include aircraft technicians, commercial and military pilots, ship machinists, restaurant workers, and disc-jockeys. The effects of VAD are visible in populations that have exposure to environmental LFN. The number of people who expose themselves to LFN is staggering, so it is time to shed light on this disease.
A proliferation of extra-cellular matrix characterizes VAD. Blood vessels become thick and impede the flow of blood. Within the cardiac structures, the mitral and aortic valves become thickened. Thickened heart tissue is the primary symptom of VAD, and it can lead to arrhythmias and death. Other symptoms of VAD include depression, increased irritability, aggressiveness, a tendency for isolation, and decreased cognitive skills.
There is growing evidence that suggests that prolonged exposure to LFN can cause harm beyond the loss of hearing. The LFN, which is below 100 Hz, is common in dance clubs, powerful car audio systems, motorcycles, and airplanes. The noise may be of such a low frequency that it is inaudible to the human ear. Depending upon the amount of exposure to LFN, the symptoms of VAD occur in three stages:
An echocardiogram can give a preliminary diagnosis of VAD. The echocardiogram visualizes the thickening of the cardiac structures, primarily the pericardium and the heart valves. This imaging may show thickened carotid arteries and abnormal cerebral blood flow. Blood tests can provide information on blood coagulation parameters, which tend to be unusual in VAD patients. Finally, an audiogram can measure an individual’s hearing loss at specific frequencies.
Although most employers require hearing protection for workers who expose themselves to high noise levels, few are aware of the long-term effects of exposure to LFN. The current legislation regarding noise assessments is inadequate and is hindering the study of VAD. Until LFN is acknowledged and accurately measured, VAD will never be fully understood. The number of people who expose themselves to LFN daily is at a critical level, so hopefully, it will bring attention to the harmful effects of LFN. If you expose yourself to LFN regularly, consider scheduling a hearing evaluation with a hearing healthcare professional.