When receiving CW, which of these frequency ranges is optimum for a band-pass filter?

When listening to CW (Morse code), operators generally prefer an audio pitch (sidetone) between 600 Hz and 800 Hz, as it is pleasant and easy for the human ear to distinguish. A band-pass filter designed for CW reception should be centered around this preferred listening pitch and have a very narrow bandwidth to reject adjacent noise. The range of 750 Hz to 850 Hz provides a narrow 100 Hz bandwidth centered right at a comfortable listening pitch. Wider ranges like 300 to 2700 Hz are suited for voice communications (SSB) and would let in too much noise for CW.