CLOSED CARS IMPROVING

NZ Truth, Issue 1189, 13 September 1928, Page 20

CLOSED CARS IMPROVING

Experitt#rit EHnuriatef Interior Noises

AWNERS of closed cars most probably have noticed that; the interior noises of the car are less pronounced when the car is full of passengers than when it is empty. .- ~A

•THIS is because the human body has 1 la large capacity for absorbing sound, partly due to the amount of clothing 1 worn. It has been found by experiment that the Capacity of a person to absorb sound is equivalent to 5 sq. ft of window space," by which is meant that the 1 carrying of a passenger is as effective aa opening a window -with- an area of 6 sq. ft. m the way of allowing interior noises to escape. It follows, therefore, that , "drumming", m. the interior of a closed car is less troublesome when the car is full of* people. ' . i 'It is due to experiments m the fast two or three years m soundkilling fabrics and methods of body construction that the modern sedan 'is so quiet to ride m. , It is not generally understood that the silencing of a closed body presents. one of the most .troublesome problems

with which, the body builder has to deal. . ■'-.' ■,- ''\ He might make a perfect body" as regards appearance and wearing qualities, yet it might,' through some very insignificant detail, be a terror to ride 1 m. . . It might be bad at all speeds, and might only be noisy at certain definite; speeds within a narrow band, say, from. 21 to 23 m.p.h., and at no other. •< ./!' ; Yet again, it might have two or three periods m which intolerable drumming occurs. . These faults have only been remedied by the most strenuous and painstaking experiments, m .which scores of thousands of pounds have been spent, It is only m the last few months that the cheaper sedans have been reasonably quiet on the road, but makers tjaye. still further to go before they can .. reckon to. have completely solved the problem of quietness.