Low volume when using speakerphone.

I am using stock 5.1 on my Moto X 2014 which I have owned for about a month. Today my wife complained of me being very quiet on speakerphone.
I have tested this again with other people and the volume is very low.

I contacted Motorola who suggested I try a factory reset, which I did for the sake of argument, and the volume is still low.
Is this something anyone else has experienced? I'm afraid I'm going to have to send it to the service centre to be fixed.:(