by ear

She started playing piano by ear when she was 4 and before long was studying the work of Bach, Beethoven, Chopin and Schumann.

The irony is that my father, my aunt and my grandmother played by ear with near perfect pitch though I don't know that any of them could even read music, and though I could, I never had it in me the way they did down through their soul.

He said that with regard to his case, he would have to "play it by ear".

He could identify many species of birds by their calls alone and sometimes taught “birding by ear” classes in Homer.

“Could play piano by ear, could hear something and play it. Also, he had a beautiful voice — booming, beautiful voice. He liked many different kinds of music. Practicing opera sometimes. He had a fascination with Enrico Caruso.”