The detective stories by Raymond Chandler featuring his Philip Marlowe character methinks qualify as being part of the 'hardboiled' detective fiction genre.
I learn that Mr Chandler wrote these stories using an Underwood Noiseless machine, a very soft-spoken writing machine. I'm imagining he would have used a portable (77?), but don't know or can't find the online reference I got that impression from.
Odd. Whilst Agatha Christies' puzzle-like 'whodunnit' stories were typed on a Remington 5T portable (pretty loud type-clack) these 'hardboiled' were written on a gently soft-striking machine (only the ka-chung of the carriage).
I wonder. Does it add something to the experience of reading or listening to a Marlowe story to imagine it having been typed with the muffled ka-chung of his Noiseless?
To try, the short story 'The Dear, Dead Days' is a very gentle story (nobody dies) and not so 'hardboiled' at all. Though there is plenty of wisecracking.
A more 'hardboiled' story to enjoy is 'Trouble Is My Business'. This one was first broadcast in 1948, starring MGM's dynamic young actor Van Heflin. The audio quality is not so good on this one and there is almost two minutes of commercial seduction to sit through (no, not soap - toothpaste). But still, do sit through the commercial going all lyrical over the minty new flavor to get to what I think is a very typical 'hardboiled' Marlowe story. Now imagine typing all this out on a Noiseless...
In any case; even today I find these are enjoyable short radio-plays. Excellent for listening to during a long drive or when tinkering (with a machine).