I've tried to look up both phrases in a dictionary but there was none.

I've heard people say 'a practised eye'... is it also correct to say 'a practised ear'?

I was required to complete this sentence... An expert's skill may lie in his possessing a practised e_ _.

A practised eye sounds more appropriate than ear. Anyone agree?
Re: P. rapae-- just a matter of counting spots, isn't it, Goldmund?
I believe that 'eye' and 'ear' are equally valid. Some people might think that the ear, as an organ of perception, has a more limited application than the eye.

That notion could very well be a misconception, though. There is the hypothetical question: Would you rather be blind or deaf?

A legitimate question that deserves to be asked here is , 'expert skill in what area?'
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Dear Anonymous,

A musicologist may have a «practised ear» if he can distinguish one concerto by Vivaldi from another.

A lepidopterist may have a «practised eye» if he can distinguish a male Pieris rapae from a female.

Kind regards, Emotion: smile

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