President Barack Obama recently signed sweeping patent reform legislation aimed at encouraging innovation and streamlining the patent application process. In signing the measure, Obama noted that when Thomas Edison filed his patent application for the phonograph, the approval process took just seven weeks.
Of the phonograph, the application for 200521 was filed December 24, 1877 and the patent issued February 19, 1878. It isn't just the elapsed time; the application was filed during the Christmas holidays.
This was indeed faster than for the light bulb improvement, on which Edison continued to improve this design and by November 4, 1879, filed for U.S. patent 223,898 (granted on January 27, 1880). This patent does NOT mention bamboo.