Directors must be viewers' ears
AS a TV drama director with over 50 years of experience, including many BBC productions, having watched Jamaica Inn I feel too much has been generalised about this production and the sound quality in today's television.
When examples of inaudible dialogue were quoted from Jamaica Inn these were only from the character Joss (played by Sean Harris) as all other characters' words were perfectly audible. And that's where the problem lies: the training of drama directors.
The director should be the ear and eye of the viewer on the set, with knowledge, self-confidence and authority to make sure the one mumbling actor cannot ruin the enjoyment of viewers.