Many modern media players can increase the speed of audio without distorting the pitch. My mp4 player (generic brand, ie no brand name) can change the tempo which is the same as increasing the play back speed. Window Media player can do the same according to Steve Pavlina
click the arrow below “Now Playing.” Then click Enhancements -> Show Play Speed Settings. This will bring up the speed controls that enable you to increase the speed of any files you’re playing.
When I am listening to podcast, I usually increase the tempo of my little mp4 to +5 which I can still fully comprehend the podcast.