More people listened to WDET this winter than last fall, according to Arbitron. That means the station has more listeners now than before the programming changes put through by station manager Michael Coleman in mid-December. In simple numbers, the station\'s average quarter-hour share (people listening for at least five minutes during any 15-minute period) is now 161,000 listeners, compared to 149,600 in the fall book. \"Certainly we have some work to do, but we\'re very encouraged by the numbers,\" says Kevin Piotrowski, WDET\'s public relations director. \"Knowing that some listeners went away, but we still have a net gain of more than 11,000 listeners, that means that those listeners were made up for, plus, plus.\"