Introduction Several epidemiological studies highlighted a synergistic interaction between noise and mechanical vibration exposure.¹ The etiologic mechanism is still missing. Moreover, the measured transmissibility from the hand to the head seems to be poor. At the shoulder, frequency over 30 Hz are practically suppressed. If there are not any vibration left, how can mechanical energy interact with the cochlea? The aim of this speculation is to approach the transmission of vibration from entering point to the cochlea from a different point of view.

Proposed methods In the seminar on hand-arm vibration exposure³ to isolated and repeated shock vibrations held in October 2015 in Beijing it was suggested that a wider spectral component of mechanical vibration may travel in the blood vessels and impair vasoregulation and nerve terminations in fingers. Such a suggestion may apply to transmission to even more far district, due to the fact that blood vessels can work as waveguide for pressure, because they are designed to be so.

Methodology Can be summarised as following. Effects of vibrations on the hearing function will be assessed by stimulated otoacoustic emission method. Vibration elicitation will be strictly controlled (shaker and 6 DOF vibrating plate). Overall vibration will be measured by accelerometers on joints and head. Blood vessel vibration propagation will be measured by high resolution, dual frequency echography^4,5 on main vessels (coronary) and small vessels. The frequency spectrum of hearing loss and blood vessels vibrations, deducted by the heart pumping effects, will be compared to look for coincidence.

References

1. . Sisto R, Botti T, Cerini L, Di Giovanni R, Marchetti E, Lunghi A, Sacco F, Sanjust F, Tirabasso A, Moleti A. Synergistic effects of noise and hand-arm vibration on distortion product otoacoustic emissions in healthy subjects. Int. J. Ind. Ergon2016:1–7. http://dx.doi.org/10.1016/j.ergon.2016.10.006

2. . Adewusi SA, Rakheja S, Marcotte P, Boutin J. Vibration transmissibility characteristics of the human hand–arm system under different postures, hand forces and excitation levels. Journal of Sound and Vibration2010;329:2953–2971. http://dx. doi:10.1016/j.jsv.2010.02.001

3. . IFA Report 5/2017e, DGUV, Hand-arm vibration: Exposure to isolated and repeated shock vibrations – Review of the International Expert Workshop2015 in Beijing. http://www.dguv.de/ifa/publikationen/reports-download/reports-2017/index-2.jsp

4. . Papadopulou V, Balestra C, Theunissen S, Germonpré P, Obeid G, Boutros A, Dayton PA, Eckersley RJ, Cosgrove D, Tang MX. Can contrast mode echocardiography help estimate bubble population dynamics post-dive? EUBS 43rd annual scientific meeting, Ravenna, Italy, 12–16 September 2017.

5. . Self-assessment of the jugular venous pulse from space and special environments – Paolo Zamboni, EUBS 43rd annual scientific meeting, Ravenna, Italy, 12–16 September 2017.