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).
Report comparing vehicle noise levels and assessing the usefulness of the measurement instrument.
| Identifier | ExFiles\Box 138\1\ scan0103 | |
| Date | 15th June 1934 | |
| -2- Bentley at 40 m.p.h. Top gear 66 3rd gear 68 2nd gear 72 Terraplane (3 gears only) at 40 m.p.h. Top gear 63 2nd gear 72 The accompanying chart summarises these figures. Usefulness of Instrument. It was found that readings on the instrument were accurately reproducible and that observations made by different people were in close agreement. From this point of view the meter would be very valuable for giving an absolute measurement of the noisiness of a car, independent of the personal impressions of the observer. In this manner direct comparison could be made between tests taken at different times and by different observers. The following considerations, however, qualify the usefulness of the meter in this respect :- 1. The meter appears to be more sensitive to low pitched noises than to high. Thus, in a quiet room, when the meter read 58 decibels, the reading went up to 60 only when someone whistled loudly a yard from the instrument. There could be a very objectionable high pitched noise in a car which the instrument would not record. 2. The instrument measured intensity of noise only, not 'irritability', which is the quality which influences a customer. 3. The instrument will not measure an intermittent noise. Hs{Lord Ernest Hives - Chair}/F.Ll.Smith. 1 Chart Att. | ||