Piano/Playing by Ear

Playing by Ear
Playing by ear is when you "pick" up notes from something you listen to. For example if you're listening to a catchy song and you want to play it but don't have the notes or score you have to play it by ear. The basic process that can be used to play any song by ear on the piano is: 1) recognize intervals between adjacent notes in a melody (e.g. in key of C, C=1, D=2, E=3, F=4, etc.) and using the intervals to help you find and play those notes in sequence on the piano; 2) play the bass note with each melodic note on the main down beats (typically note at 1, 3, or 5 intervals below the melodic note); and 3) play the notes of a specific chord based on the a given bass note (e.g., notes at 1, 3, and 5 intervals above the bass note).

Useful Tips:
 * 1) A good start when trying to play a song or a tune by ear, is to start humming it. This might not be a good choice when other people are around you if you want to keep a certain facade of sanity, but it certainly helps. The reason is that sometimes the hardest part is actually finding the main notes in the song, and when you hum a song, you are really humming the main notes! So just hum away, and start playing by ear.
 * 2) Play slowly! If you're having trouble picking something up, you are not going to make it easier by playing with haste. Just think that there are only a limited amount of notes you use when you're a beginner, no more than 10-15, so finding the first note is not that hard if you are patient. Of course if you're going to guess every single note it would take a really long time playing a long and complicated song by ear- that's why you practice playing short, simple songs by ear.
 * 3) Start the song on the key of C to avoid having to use any of the black keys. To find the first note of the song on the piano so that you play the song in the key of C: 1) hum to the very last note of the song; 2) hum the first note of the song; 3) hum up or down from the last to the first song notes to count the number of intervals separating these two note; and 4) place your finger on the key of C on the piano and go up (or down) the number of counted intervals to determine the starting note of the song.

= also note that there are a lot of different materials online that might help you train your ear. Earmaster for example, is a program that aids you identifying intervals, scales and chords. it also aids in the imitation of rhythms. Alternatively you can try to guess a key that is played on the piano at random.