I've been practicing my sightreading on my fretless bass, and I've come to the conclusion that my intonation sucks. I find myself wishing that I had a recording of this music, so that I can check my intonation against that. But there's so much music out there that this is an unpossibilty. What if I'm playing by myself? How do I test my intonation? And then it hits me: tuners detect what notes I am playing. They also will put out tones of various pitches. Why can't somebody make a tuner that will detect what note I am playing (or close to it), while simultaneously putting a note out that I should be playing? Eureka! An idea! Learning intonation should be a hearing discipline, not a visual one - relying on fretlines or watching the tuner is self defeating. An invention such as the one I've described would be a great help in developing a good sense of pitch. I don't think it would be a terribly difficult thing to make; perhaps it would be nothing more than a mod on an existing tuner. I'm not an engineer, and no whiz when it comes to electronics, but it strikes me that it's not an unpossibilty. Some tuners are really fast detecting pitch, so it might be useable for fast runs even. Who knows? Could something like this be done? Anybody care to steal this idea from me and make it a reality?