From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Experiments conducted with a Standard Telephone Co. Acoustic Meter to measure noise from various sources.
| Identifier | ExFiles\Box 138\1\ scan0091 | |
| Date | 14th May 1934 | |
| X634 Rm{William Robotham - Chief Engineer} To Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}..........from Ev.{Ivan Evernden - coachwork} Copy to Sg.{Arthur F. Sidgreaves - MD} Worl E.{Mr Elliott - Chief Engineer} Ev{Ivan Evernden - coachwork}2/IH.14.5.34. re:- Standard Telephone Co. Acoustic Meter. ----------- We made some experiments with one of these meters on Friday but our proposed tests were partially spoilt due to the representative having to cancel the morning appointment for one in the afternoon after we had arranged for a number of cars to be available at 10 a.m. The meter works on the principle which was described in your memo. With the instrument one could almost instantly measure the noise in a motorcar. For instance, it was possible to first measure the noise in the car from exterior sources when it was stationary out in the open country; then to measure the noise when travelling at various speeds. We then measured the noise at those same speeds in third gear. We were then able to see how much of the noise in the car was due to the fact that it was travelling at a given speed in top gear, and how much more noise there was when it was travelling in third gear at the same speed. Subtracting these two we obtained a measure of the increase in noise for a given speed between top and third gear, due to the increase in engine revolutions and the utilisation of the gear box reduction. We also used the instrument for measuring the noise emitted by machinery and an electrical motor. The instrument was also tested on an Underground train, when it was possible to show how the noise varied in volume depending upon the condition of the track and the conditions of the tunnel and the sub-soil. Unfortunately, we had not a car that boomed, but we have some doubt as to whether it would be possible to measure booming with this instrument, because the booming which troubles us is a vibration so low that it is more felt than heard. It was possible to measure the amount of wind noise on the car at any speed by sitting in the front seat and coasting. The Standard Telephone Company have offered to give us another demonstration because they had spoilt our arrangements, and we think we -1- | ||