What is "Voice" for in the key editor?

I see in my Key editor this option to assign vocies to midi events. Can someone please let me know what this is used for? The manual is not very clear here.

here is a picture

see SATB - Wikipedia

When you assign voices you can use filters for them in the logical editor and use them to assign Score Editor polyphony.

Thanks. I thought the channels assigned the voices into SATB. When I work with the score editor and use the “polyphonic” staff setting it assigns the voices into channels. I am not seeing where the “voices” fits in to this? Arent the “channels” used for this?