Looks like selling a few million copies of Guitar Hero doesn't get you any special treatment from Sony Computer Entertainment America. According to PSP Fanboy, the folks at Harmonix pitched a sequel to Frequency and Amplitude designed for the PlayStation Portable and were shut down by SCEA.

Bummer, but I can't say I'm surprised. The two rhythm games, while fun and critically acclaimed, didn't exactly burn up the sales charts. Despite the fact that Harmonix has found great success with their Guitar Hero franchise, they aren't a household name on par with someone like Rockstar or Nintendo who can shift software based on their pedigree. I consider this a personal loss, but one that I'm coming to terms with.

Maybe we'll see a proper sequel hit the PlayStation Store in the future with bitter tasting musical microtransactions

Via Kotaku