His singing voice was also exceptional, and he was said to be able to sing operatic parts from baritone to soprano range. Fellow musicians and singers were universal in their praise of Jackson, most calling him "the greatest", and even the far-from-modest Jelly Roll Morton ranked Jackson as the only musician better than Morton himself. Morton met Jackson in 1906. Jackson became a mentor to Morton. Jackson also wrote many original tunes, a number of which he sold rights to for a few dollars or were simply stolen from him; some of the old time New Orleans musicians said that some well known Tin Pan Alley pop tunes of the era were actually written by Jackson.