An occupational disease that affects many who aren’t even aware of its existence, Vibroacoustic Disease (VAD) has changed the lives of thousands of people. Caused by long-term exposure to high intensity (above 110 dB) low-frequency noise (100 Hz), it’s often low enough that it’s imperceptible to the human ear.
Though it’s not always noticed audibly, the body does react in a variety of ways. Patients report feelings of their entire body vibrating, anxiety in certain situations such as needing to getaway. This malady has been linked to the body’s fight or flight instincts, which explains how this anxiety or unrest makes the person want to move away from the source of the noise, whether they ‘hear’ it or not.
This disease is often seen in those who work in aircraft or military settings such as flight crews or aircraft mechanics, musicians, and restaurants or factory workers. It’s also been noted in clubs where music is blasted loudly, extremely powerful vehicle audio systems, sounds from motorcycles, and the passenger cabin of small, twin-turboprop planes.
Studied since the 1980s, scientists have determined that VAD can cause significant neurophysiological health risks, the least of which is loss of hearing. Some of the documented symptoms include:
- Abnormal cardiovascular structures (carotid arteries, cardiac valves, pericardium)
- Aggressiveness
- Balance disorders
- Depression
- Late-onset epilepsy
- Lung fibrosis/ tumors
- Mood swings
- Neurological problems
- Pulmonary fibrosis
- Rage
These symptoms and their severity depend on how much contact the person has had to low frequency noise (LFN). The disease is broken down into three stages.
Stage one, mild VAD is typically seen in patients with one to four years of contact to high intensity, LFN. It’s often characterized by bronchitis, heartburn or indigestion, infections of the mouth or throat, and slight mood swings.
Stage two, moderate VAD involves patients with four to ten years of exposure. Distinguishable by allergies, back and chest pains, blood in the urine, conjunctivitis, fatigue, inflammation of the stomach lining, mood swings, and parasitic, viral or fungal skin infections.
Stage three, severe VAD includes those who have more than ten years of contact. The issues are much more serious and debilitating at this stage. Balance disorders, a decrease in visual acuity, duodenal ulcers, epilepsy, hemorrhoids, hemorrhages of the conjunctive, digestive, and nasal mucosa (small nose bleeds), headaches, intense muscular pain, neurological or psychiatric disturbances, severe joint pain, spastic colitis, stroke or heart attack, suicide, and varicose veins are all part of the advanced stage of this disease.
High intensity, low-frequency noises or rather the subsonic vibrations associated with these noises are damaging to every cell in the human body. As we experience these vibrations, our body fills the bloodstream with adrenaline and endorphins needed to survive a major, upsetting event.
This fight or flight response is natural, but such a flood can cause a lack of awareness, confusion, and disorientation. When this happens, it can be dangerous to our overall health. Long term exposure raises the risk of heart attacks, headaches, back pains, fatigue, and ulcers. There is also the potential for damage to the inner ear.
When these extreme noises occur day after day such as in a work environment and hearing protection is not used, there is the possibility that the cilia can be damaged. These small hair-like fibers inside the inner ear capture vibrations and turn them into sound, providing they are at a level that the human ear can pick up. Once the cilia are damaged or die off, they cannot be regrown and the ability to hear decreases.
VAD involves the cardiovascular, muscular, and even the neurological systems of the human body. While there is an ever-growing base of knowledge on the subject, information is still somewhat limited. Scientists and researchers are working to gain better results and facilitate treatments for this type of disease.
Currently, few companies are utilizing the opportunities to protect their employees and clients. A Dallas-based company is stepping up to the plate and offering special noise cancelling systems to go in the cabins of aircraft.
These devices recognize and eliminate these harmful frequencies and amplitudes, removing undesirable low range noises that emit between 80 to 360 Hz. The system utilizes strategically placed microphones within the cabin to identify noises within a specific range.
The noise is then picked up in analog signal and transmitted to a control box. At that point it is broken down into amplitude, frequency, and phase. It’s then redistributed by computer at the same amplitude and frequency, but the phase is adjusted 180 degrees, sent via analog signal and received by several speakers which release it at a tolerable level.
These effect of these sounds on the human body as well as the hearing can create a life long road of constant medical monitoring as well as neurophysiological examinations. By using psychometric or performance testing as well as other types of diagnostic testing, people exposed to high intensity, low frequency noises can be evaluated over time.
The lack of information available on the topic means that there isn’t as much awareness surrounding vibroacoustic disease. If you or a loved one are having symptoms of vibroacoustic disease, visit your hearing health professional today to see how they can help diagnose and treat this condition.
