Wild stuff, never knew about these old mechanisms. Doesn't seem too loud however. https://www.youtube.com/watch?v=cNNKLuM8yY8

Try https://archive.org/details/EastLangtonUax13TelephoneExchang... That's a standard UK rural exchange. Capacity 100 lines! The last few decomissioned went, in full working condition, to museums.

Background noise is the motors for the tone generator, probably the cable compressor too. The louder noises are the call routing and reset. Background noise would normally be a fair bit louder - I'm guessing he had mic right up against the rack for this.

Or a town exchange: https://youtu.be/xUOh9fCSgqw

Towns had much larger exchanges, and they were loud. Probably enough to have hearing loss if you worked there. Only visited one once, decades ago.

Also had a distinctive smell - machine oil, burnt electrics (50v), solvents. Lovely.

A room full of those, piled up in columns/towers seven or eight feet tall, gets pretty loud.

But yeah, as mentioned, a building with decent insulation can contain the noise. A flimsy cottage, probably not.

I doubt it. I walked past a large strowger exchange building as a school kid every day in the UK heard nothing from outside.

What an irony that this was invented to prevent fiddling about with things, considering how fouled up it all got.