keep your ears open
From Longman Dictionary of Contemporary Englishkeep your ears openkeep your ears opento always be listening in order to find out what is happening or to hear some useful information I hope you’ll all keep your eyes and ears open for anything unusual. → earExamples from the Corpuskeep your ears open• All of you - walk around Pentonville and keep your ears open.• They had a kid copper keeping his ears open.