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).
Table of noise level (db) test results for a 25 HP Barker Standardised Enclosed Limousine under various conditions.
| Identifier | ExFiles\Box 138\1\ scan0116 | |
| Date | 21th February 1935 guessed | |
| - 2 - exploited quite recently. We are keeping in touch with research here and in America as well as with the Standard Telephone Company, and as soon as any advance is made we shall report again. Ev.{Ivan Evernden - coachwork} DATA of TESTS. Car - 25 h.p. Rolls-Royce - Barker Standardised Enclosed Limousine Observations made from the rear seat. db.{Donald Bastow - Suspensions} Gear Speed in M.P.H. Conditions Inst.No.44. Inst.No.45 4th 40 Level. No wind. 46 48 4th 40 Full throttle up 56 54 Brockley Hill 4th 40 Wind ahead. 54 52 Level Road 4th 50 - " - 60 58 4th 60 - " - 68 66 3rd 40 - " - 58 56 2nd 40 - " - 68 68 Ev.{Ivan Evernden - coachwork} | ||