Sound in the military environment : detection, measurement and perception : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy, Massey University, Palmerston North campus, Institute of Food, Nutrition and Human Health [EMBARGOED until further notice]
The sound environment in which we work and its effects on us has been the
subject of considerable research over the last century. With the advances in technology
and electronic engineering, increasingly sophisticated laboratory equipment has been
developed that has been able to be applied to the biological sciences. Accordingly
much progress has been made in understanding hearing in both man and animals.
Although there is significant new information currently available, much of it has not
yet filtered into the health and safety workplace management system. The continued
reliance on the A-frequency weighting is one example where scientific progress has
outstripped current management practice.
This research sought to determine and measure the acoustic spectrum in various
working scenarios within the New Zealand military, particularly in land transport that
may amount to long periods for some soldiers. In addition the research included a
pilot study of the effects of these sound environments on military personnel with
respect to hearing and cognition.
The research included a number of novel techniques including binaural manikins
developed to quantify the sound within military vehicles, from a human perspective,
utilising the latest SAM (Spectro-Acoustic Meter) technology. In addition, a water filled
manikin (“Aquaman”) was constructed with internal sensors to determine the effects
of external sound and vibration as transmitted into the human body. Comparison of
spectra and energy levels facilitated modelling of the total sound absorbed by a human
The research showed that in the military vehicles examined, the sound
environment is neither homogeneous nor symmetrical and likely contributed to the
hearing and cognition effects observed. As the research had to fit in with the New
Zealand Army’s daily operations only a small number of participants was available at
any one time. Further research with a larger population is necessary to qualify and
quantify the initial results obtained from the pilot study.