To add my 2 pennies, paper is used because of its lightweight(for fast transcient responses and dynamics)characteristics and ability to minimise sound coloration. Though its starting to finally show its age as there are new materials that will far exceed paper in terms of sound quality,output etc. Titanium alloy being one of them, but you dont see many speakers with titanium cones due to expense to mfg. them. But dont shy away from speakers that use a pulp cone. There are too many great sounding speakers that use them.
