play by ear

Verb

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

1. (intransitive, transitive) To play guided by one's musical perception and intuition, rather than from a written score.
2. (idiomatic, intransitive, transitive) 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.
   • There over, hereunder / Or up above, don't wonder / We can always play by ear / But that's the deal, my dear2001 August 30, Shakira, “Whenever, Wherever”, in Laundry Service

   Synonyms:

   fly by the seat of one's pants, make it up as one goes along, wing it