Metro radio advertising revenue is running hot and cold but experienced an overall 3.0 per cent decline nationally to $44 million in January compared with the same period last year. Traditionally the country’s biggest market, Sydney suffered a 6.2 per cent drop to $12.844m while Melbourne took the mantle of the No.1 radio city with $13.612m in revenues, slipping just 0.9 per cent compared with last year.