Accents can add to it, possibly less of a problem with English accents, but I've had American and Canadian friends who couldn't hear a change in tone because the accent was so foreign.
I have been completed on being very patient and professional over email when that wasn't my intention so I might need that style guide to translate to American.
I have been completed on being very patient and professional over email when that wasn't my intention so I might need that style guide to translate to American.