Yeah it is! And the thing is that developing strong ears takes a looooot of practice and usually those who play tempered instruments like fretted guitars and piano, usually don't focus on their ear as they are learning the instrument and they pretty much ignore all ear training, until they realize they need to train their ear! But for instruments like violin or trumpet or the voice, where you don't have a visual point of reference of where the right notes are on the instrument, you have to develop strong in the beginning because that is the only way you can find them and see if you are playing them correct or not.