In theory...

If it is written as `an .ear file` then it is pronounced
 - "an ear file" [æn ir faɪl] or
 - "an E A R file" [æn i eɪ ɑr faɪl].

On the other hand `a .ear file` suggests the writer intented
 - "a dot-ear file" [eɪ dɑt ir faɪl] or
 - "a dot E A R file" [eɪ dɑt i eɪ ɑr faɪl].

However, this only applies to situations where one or the other has been used on purpose. Most native speakers probably don't do this consciously either, and not all users are native English speakers.