How can preachers hear loving critique?

I must mention a troubling conversation I shared recently with a group of church goers from different churches. One said: "You teach preaching. How can we get through to our preacher? We love him, and rate his Bible knowledge and giftedness very highly. But, everytime he preaches he speaks too fast and goes on for nearly an hour. He's too fast and gives us too much to take in! I've emailed him and asked him gently to slow down and cut down. BUT HE TAKES NO NOTICE."

Others in the group asked why it is that preachers can become so protective that they reject even loving feedback. I believe this is an important issue.

As a preacher I know receiving critique is difficult, because sometimes it may not be kindly given or fair. But how am I to learn about basic communication flaws if I don't listen to others? If I preach too fast, for example, this can be/should be corrected. But imagine preaching for years and never knowing! Is there some way that we preachers could hear loving critique without feeling crushed?

I couldn't answer the opening question. Do you have any suggestions as preachers and listeners?