Appearing intimidating when you don't mean to be

Be quite tall and well built . Add a loud voice that gets louder when you're passionate about something( my voice just seems normal to me in terms of loudness) .

If I'm honest the voice thing perplexes me . I've had quite a few times when I've been asked to repeat things or people have misheard what I've said . Were they all hard of hearing? Was I talking too softly ? Perhaps my diction is bad ?