I’m still trying to figure out exactly what these things are supposed to do, but Tascam has just launched a pair of MP3 trainers that look like they belong in the 1990s. The MP-BT1 is being marketed as a bass trainer, presumably allowing you to train the way your bass sounds? It comes with Hi-Z Bass input, multi-effect for bass, 7 band graphic equalizer, bass cut on MP3 playback, and a bass range booster and enhancer for MP3 playback.
The MP-VT1, pictured, is the other side of the coin, being tossed around as a voice trainer. The vocal trainer comes with a microphone input, built-in reverb and echo, and mic volume control. My guess is that the Tascam MP-VT1 works much like Karaoke Revolution for the PlayStation 2, except less fun and more technical.
Both devices come with 1GB memory and are destined for the Japanese market only. No word on price.