The EE type 4s/class 40s were never quiet...I lived in Manchester in 1978/79 and once went on a MerryMaker excursion to Edinburgh behind one - both ways over Shap and Beattock
I did read once (Modern Railways I think) that, after electrification, Class 40s being not infrequently sent out long distance on the WCML were regarded as a right nuisance in Carlisle signal box, as most timings had been based on a Class 47 at least. There was no information of what power was on, and as the box faced the running lines, a moan would go up as one was seen to roll past, having slowed things behind over Shap.
Meanwhile ... back on the WR at Taunton, the hydraulics, high-powered small engines, were notably quieter as they accelerated away than any of the replacing Sulzers (we were long gone when the Class 50s came along). For all that much has been written (somewhat unaccountably, I find) about hydraulic unreliability, they were by and large fine, and operated to schedule, even the North British built ones, and ran well at high speed. Maybe a bit uncomfortably for the 4-wheel bogied Warships around downhill reverse curves with the power off, but still apparently more comfortably than a Britannia. The noisiest were, surprisingly, the Hymeks, as their single engine instead of two made the pulsing of the exhaust much more noticeable. Getting back to what was discussed earlier, all the hydraulic engines, sometimes described as "German", were like the Sulzer, just imported drawings. The MAN engines were built by North British in Glasgow, and the Maybachs were built by Bristol Siddeley, later part of Rolls-Royce, at a factory in Coventry.
Rewatching Cl.58 clips on YT, it does sound rather Sulzer-esque. 
