From Robert Pasnau (and here), who directs us to LibriVox, a website with readings from public domain books (at least PD book in the USA) which includes—wait for it!—a section of readings from the Summa theologiae! Currently you'll find there readings from Questions 1-26 of the Prima pars, in a variety of formats. The reader is Jim Ruddy, using the older English Dominicans translation. Now you can listen to the Summa while you go for a jog, wash the dishes, or mow the lawn.