HELSINKI, Finland, Nov. 26 (TNSres) -- The University of Helsinki issued the following news release: Researchers at the University of Helsinki performed acoustic impulse response measurements in front of 37 rock painting sites and found that the same vertical rock surfaces that have the painted elks, humans and boats, are also effective sound reflectors. Finnish prehistoric rock paintings (5000-1500 BCE) on the cliffs rising directly from the lakes are acoustically special environments. Whe more PR