It wasn't called the "Whispering Giant" for nothing - it was probably the quietest turboprop of all - it had to be - the actual engine was buried inside the thickest cowling ever, it had the intake air passages running through it. The 180 degree turn where the air went inward and entered the compressor was well back and so inlet noise was muffled. and the tailpipe was so long it made a muffler too. So actual engine noise was very low. At power of course, the prop made a good deal of noise.
Of course the joke was to call it the "Whimpering Giant" with four mighty "Protesting" engines. I was chastized once for calling it that by a former Bristol exec and I informed him I had learned it from a Bristol engine rep who fortunately had long retired.