"unerring ear" is a correct expression that can be used in written English.
It typically refers to an ability to listen attentively and accurately. For example, you could say, "Her unerring ear was able to pick out the subtle nuances in the music."
He has an unerring ear and an unbeatable sense of humor.
By Hilton Als The playwright Danai Gurira has a nearly unerring ear for making popular theatre without compromising authenticity.
Mr. Isserlis handled both works with his customary persuasiveness and unerring ear, his gut-stringed instrument singing in its highest register and purring below.
Trouble in Paradise, with its unerring ear for political cant, is a book that everyone, not least the Masters of the Universe, would profit from reading.
This novel showcases many of Mr. Ford's gifts: his ability to capture the nubby, variegated texture of ordinary life; his unerring ear for how ordinary people talk; his talent for conjuring up subsidiary characters with a handful of brilliant brushstrokes.
I found her taste - in plays and in acting - to be infallible, even if she was always tentative about asserting it, and she had an unerring ear, nose and eye, for the bogus.
The drug industry has an unerring eye for institutional weaknesses.
But for more than 40 years now, Mr. Harlow has been affectionately known in the Latin music world as "El Judío Maravilloso" ("the marvelous Jew"), a pianist, songwriter, producer and arranger with an unerring feeling for clave, Latin music's five-stroke beat, and an ear for hits.
For to produce finely etched music demands a great ear, a large heart, a rich and deep personality, and an unerring sense of drama and pacing.
The sensibility is unerring.
Not every instinct was unerring.
