The phrase "a trained ear" is correct and usable in written English.
It is typically used to refer to someone who has developed the ability to discern subtle differences in sound, often in the context of music or language.
Example: "As a musician, she has a trained ear for identifying different notes and harmonies."
Alternatives: "an experienced listener" or "a discerning ear".
Just by listening with a trained ear, the conductor knows immediately how well the orchestra has done.
Different species of bat operate at varying frequencies and a trained ear is able to distinguish each bat's call.
That speech was instantly recognized, by those with a trained ear, as the language of the Revolution in Military Affairs.
Some are easily discernible, nevertheless, in some other cases a trained ear might be necessary to perceive them since they might be imperceptible.
An artisan with an experienced hand and a trained ear can sense the effects of minute adjustments that a machine could never take into account.
"You don't need a trained ear to hear the complete lack of so many things: imaging, the width and the depth of the sound stage.
To be excellent, a sound editor needs not just a sharp, trained ear, but also a gift for imagining what a sound could do, what someone else might hear.
Though Ms. Jensen said most systems in a box sound unsatisfyingly tinny to the trained ear, they offer a good way to start.
Could he have used it effectively without the trained ear of a musician that can hear the whisper of a valve not closing properly as easily as the difference between the styles of James Galway and Jean-Pierre Rampal?
Noreña et al. [ 41] reported a significant change of tinnitus percept in the trained ear after frequency-discrimination training.
And if he isn't always playing his early repertory -- his first new album in nine years, "Joao Voz e Violao" (Verve/Universal) contains seven songs he hasn't recorded before -- the style of his music sounds to all but the most trained ear like a continuing extension of his first eureka moment.
