play it by ear, to

If you play it by ear, you deal with things as they happen, rather than following a plan or previous arrangement. `Where will we stay in Gloucestershire?' — `Oh, I guess a bed-and-breakfast place. We'll have to play it by ear.' I don't know what will happen next. I'm playing it by ear. Note: If someone plays a piece of music by ear, they play it without looking at printed music.

To act according to the circumstances; improvise: I don't have a set schedule, so we'll have to play it by ear.

To improvise; to act as the situation requires, without advance planning. This term for playing instrumental music without reading the notes from a score, but simply going by the sound, dates from the seventeenth century. It was not transferred to other kinds of improvisation until the mid-twentieth century.