play by ear

English

play by ear (third-person singular simple present plays by ear, present participle playing by ear, simple past and past participle played by ear)

(transitive and intransitive, of music) To play guided by one's musical ear, rather than from a written score.
(transitive and intransitive, idiomatic) To do by guessing, intuition, or trial and error; to react to events as they occur, often with risk of negative outcomes; to improvise.
If they ask for something we didn't prepare, we will have to play it by ear.
- 2001 August 30, Shakira (lyrics and music), “Whenever, Wherever”, in Laundry Service‎^[1]:
  There over, hereunder / Or up above, don't wonder / We can always play by ear / But that's the deal, my dear

(do by guessing, intuition, etc, reacting to events as they occur): fly by the seat of one's pants, make it up as one goes along, wing it

play music guided by one's musical ear

Chinese:
Mandarin: 憑記憶演奏／凭记忆演奏 (píng jìyì yǎnzòu)
Danish: please add this translation if you can
Finnish: soittaa korvakuulolta
French: jouer à l’oreille
Galician: tocar de oído
German: nach Gehör spielen
Polish: grać ze słuchu (literally “play from hearing”)
Portuguese: tocar de memória (literally “play from memory”), tocar de ouvido (in imitation of a performance)
Romanian: cânta după ureche
Spanish: tocar de memoria (literally “play from memory”), tocar de oído

do by guessing