Daniel Barenboim: Intonation

One of the most delicate subjects in this area is intonation, and I had my share of problems with intonation at the beginning of my conducting days. Having grown up playing the piano, I did not always notice i f something was not quite clean from the point of view of intonation in the orchestra. I knew what was not quite clean if a wrong note was played, and obviously I heard that chords were out of tune, but I could not always indicate which instrument was too low and which too high.
If you do not hear a chord very clearly or very cleanly, just say what you are thinking at the moment - that this is too high and that is too low - you may be right, and then you will know if this is the case for the next time. or you may be on the wrong track altogether and tell a musicain that he is too low and he may say "I was not too low, if anything I was too high". You musn't be afraid of saying something wrong, because that is how you will train yourself. And this is how I learned. I was not embarrased, if I heard something unclean, to say, this is too low.
At the beginning it often happened that a player replied: 'What do you mean , too low" I was far too high!" Then I would say, "Yes, you are right". This is how you train your ears. But you must be open about it, and not afraid of making mistakes. It is rather like learning a strange language. If you are afraid of making mistakes you will never learn to speak it.