ONE only needs to listen to Jude Law murdering the Aberdonian accent in thriller Black Sea to know that Scots dialect can be a tricky beast. Think Mel Gibson in Braveheart or Christopher Lambert in Highlander: there has been some awful assaults to the ears over the years.

The woman charged with helping Outlander avoid a similar fate is dialect coach Carol Ann Crawford. At the Cumbernauld studios where the hit US television series is based, Crawford shares the tips she has given the actors.

"With accent and dialogue you are building the character, but it is also bringing a sense of time and place," she says. "You notice that in the first series our heroine Claire, who speaks in an upper-crust English accent, contrasts with the Highlanders who are all Gaelic speakers."

Crawford, who is from Bute and now based in Edinburgh, often uses recordings of native speakers when working with actors, while others prefer more detailed analysis or image-based explanations.

With the Highland accent, she says, the sound is up and forward in the mouth rather than down and back as it is in Aberdeen. Where Glasgow has a distinctive scoop and rise intonation pattern, the Highland accent has a more lilting quality.

"A lot of what I do is practice and repetition," she says. "When I'm working with the actors, I break down the sounds. I talk about the tune and rhythm. Some accents have a very distinctive rhythm. For instance, there is a scoop and rise to the Glasgow accent where the vowels get stretched.

"With the Highland accent, there is a lighter feeling to it. The Gaelic in the background informs the accent and so you get a softness and a little bit more of a lilt. Sometimes I describe the tune as a boat bobbing on the waves.

"Actors often respond to images rather than technical details. I can say to someone 'put your tongue in this position' or 'round your lips', but often it is the image that is the most successful thing. If you can imagine the landscape, that also helps inform the sound."

Crawford, who trained at the Royal Central School of Speech and Drama in London, praises Outlander actors Caitriona Balfe ("she has captured that 1940s way of speaking where the tongue is little bit higher and everything is that a little bit crisper") and Sam Heughan ("he has embraced the Gaelic and loves the sound of it") for their technique.

Their cast-mate Duncan Lacroix, who hails from Kent and spent several years living in Ireland, was another star pupil. "What has been gratifying is that a number of crew members have said: 'Oh, I didn't realise Duncan wasn't Scottish,'" says Crawford. "He has found the right level with it.

"There is no one size fits all. You have to work with an actor and take into consideration the background of the character. With some of the guys, the danger when they started was that the Glasgow accent is so dominant."

Easterhouse-born Gary Lewis – who plays clan chief Colum MacKenzie – would be one such example. How did Crawford tackle this? "We try to soften it a little and get a wee bit more of a lilt. In Glaswegian you get a lot of glottal stops, so it is about eliminating those and getting a little bit more of a flow and tune to it."

One interesting nugget is that there are no Gaelic subtitles in the first season of Outlander as showrunner Ronald D Moore reportedly wanted viewers to experience the abject isolation felt by Claire after she was parachuted into the 18th-century Highlands.

Crawford describes Scots and Gaelic as extremely "muscular languages" that there is a knack to mastering. "You have really got to get the feel in your mouth," she says. "When you are working with actors, voice and language can't happen just from the neck up – it has to happen from the soles of their feet. They have got to own the language."

The new series of Outlander, which sees the action transfer partly to France, brought a fresh set of challenges. "We have quite a number of French cast and my work has largely been about helping with pronunciation for those who are less familiar with English," says Crawford. "I have to say, though, they are fantastically good and sometimes we have to persuade them to sound a little more French."

Read more: a journey behind the scenes of TV series Outlander

Although every cloud has a silver lining. "The setting is, of course, very different," she says. "We are in the beautifully decorated apartments of Paris and Versailles – that has been a nice contrast to slithering around in the mud."

Can Crawford watch television without her teeth being set on edge by ropey dialect – or is it impossible not to pick holes? "Only if something is really bad," she says. "Then what happens is that you stop believing in the situation. I enjoy watching films, television and theatre. I get very absorbed in it. If you hear sounds that are not quite true, you take a step back and are not so involved."

And her professional opinion on Braveheart … "It gets a terrible slagging off, but I think sometimes you have to accept there are compromises," she says diplomatically.

Crawford believes it would be a "wonderful spin-off" if Outlander was to spark renewed interest in Gaelic and old Scots words among younger generations.

"Those languages deserve to be heard," she says. "Outlander reaches a very wide audience and so hopefully it is reaching people for whom Gaelic and Scots is perhaps something they wouldn't normally encounter."

Outlander season two will be available exclusively on Amazon Prime Video from April 10 with new episodes airing weekly

Read more: Outlander star Sam Heughan on Scottish independence, super fans and his life changing role

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