As every opera goer will know, the display of English translations of the singers’ words above the stage is a mixed blessing. Certainly, this helps greatly with the understanding of the plot, but it can be a constant distraction from the main event: what is happening on stage.

Now the UK’s National Theatre has exploited technology to come up with an alternative, aimed not at the linguistically challenged but at the hearing impaired.

It has launched a trial providing deaf and hearing-impaired theatregoers with Epson Moverio BT-300 AR smart glasses, enabling them to read subtitles in their field of vision when they are watching the performance.

Epson claims the Moverio BT-300 is the lightest binocular see-though smart glasses on the market. They use “breakthrough silicon-based OLED (organic light emitting diode) digital display technology, enabling truly transparent mobile augmented reality (AR) experiences for consumers, government and business,” according to Epson.

Epson says they are lightweight and comfortable enough to be worn throughout a performance, and users are able to change the position, size and colour of the subtitles to suit their own preferences.

“In true augmented reality fashion, the Moverio smart glasses will always maintain the subtitles well within the wearer’s field of vision at all times allowing them to easily follow the actors' performances whilst simultaneously reading the captions,” Epson said in a statement.

Also, according to Epson, on-board sensors enable the Moverio BT-300 to determine the location of objects in the real world enabling the glasses to lock display content to real world objects.

The National Theatre’s trial will run until October 2018. In Australia the glass are available on Epson’s website for $1,199.

Epson previewed the BT-300 back in February 2016 at Mobile World Congress and launched the product in Australia in June 2017.

At the Australian launch Epson positioned the Moverio BT-300 smart glasses as being mainstream now and key to a wide variety of consumer, commercial and government uses, including flying drones, aerial photography and videography, medical surgery, VR learning, AR learning, emergency services response and rescue operations.

They come with a hard-wired Android 5.1 based processor with touch pad and button that can connect to external systems via Wi-Fi or Bluetooth.

Epson operates an online store from which Moverio users can download apps. At launch in June there were 345 apps. The number has now grown to 100.