For single-sideband phone emissions, what would be the bandwidth of a good crystal lattice filter?

Single-sideband (SSB) voice transmission requires just enough bandwidth to pass human speech intelligibly without wasting radio spectrum. Since the essential frequencies for voice communication range from roughly 300 Hz to 2700 Hz, a bandwidth of around 2.4 kHz is ideal for capturing the audio while blocking adjacent signals. A good crystal lattice filter designed for SSB phone emissions will have steep skirts and a bandpass of exactly this 2.4 kHz width. By contrast, a 500 Hz filter would be used for CW (Morse code) where a much narrower bandwidth is needed, and a 6 kHz filter would be used for standard AM, which requires double the bandwidth of SSB.