Can someone identify this patch?

Is there a small instrument (cell-phone size) that can identify the key someone is singing in?

• Very good musicians can easily identify the key someone is singing in and join in with the accompainment. Not-so-good musicians, like myself, find this extremely difficult to do. What would be helpful is a small instrument (cell-phone size), with a built-in microphone, that can process the sequence of sound waves and identify the key that the person is singing in. Using this info, I can then easily join in with the accompainmet on a guitar or keyboard . Does such an instrument exist?

• Answer:

  Yes, but nothing that size. There computers to which you can hook up microphones and find the key then, but otherwise no. What DOES exist is a chromatic tuner, which will identify a pitch that someone is playing. It has a microphone and also tells whether the instrument is out of tune and which way. I would recommend the Sabine Metrotune, a combination metronome tuner, that allows you to identify a pitch. That might help, but you have to be able to identify which note is the tonic note in the key. It's around 35 bucks, it's battery operated and I use it to work with my sax. You can also input a guitar chord to tune it, or hook up a mic to an instrument to tune it, or find out what pitches its playing.