I started hearing this humming sound coming out of the front end of my 2014 Mazda 3 Skyactiv. The high pitch sound is audible when travelling 20 km/h or higher. The sound does not get any louder at a higher speed but the pitch is higher. I tried to get an opinion from the dealership but all they could tell me is that they would have to hoist up the vehicle and try to trouble shoot the problem. According to the dealership it could cost up to $400 just to troubleshoot. Any ideas??