Audio navigation

Audio navigation follows the ITU-T. F.921 recommendation. That means, that you have the capability of providing really detailed navigation instructions through writing or audio. If you are interested in following the recommendation, it is recommended that you familiarize yourself with it before creating your own setup. The terminology we use matches with the ITU terminology for ease of setup. You can find the ITU-T. F.921 recommendation here: F.921 : Audio-based indoor and outdoor network navigation system for persons with vision impairment (


By default, our audio navigation utilizes  native text-to-speech capabilities. The audio is produced on iOS by operating system level Text-to-Speech capability, and on Android through utilizing the pre-installed and pre-enabled Google Text-to-Speech application. The sample application picks up the language from the device language automatically. You can find the list of supported languages through these links: iOS Android

If you are interested in more fine-tuned options, you can also  look at other options, such as Read Speaker, Acapella or Microsoft offerings. Do note that the translation should happen through an on/device SDK in order to provide rapid translations for to cater for the navigation experience.

The use of these requires extra adjustment in the integration (extra charge) + the systems charge for their usage.

Wayfinding metadata

Wayfinding metadata is instructions given to the end user, when their path goes through an elevator, escalator or stairs; or when a user arrives to their destination. 

Elevator: standard navigation instructions will say: " take the elevator on the left to the third floor". You might want to add some more information here, especially if you are doing navigation instructions for visually impaired users. For example, you might want to mention that the elevator can fit 6 people. 

Destination arrival: standard navigation instructions will say: "You have arrived to your destination Restaurant Sushi boat on your 3 o'clock". For specific user groups, you might want to add additional information, such as "menus also available in Braille".

Note: This information needs to be relevant to users approaching from all directions. Avoid words right, left, after and before as those easily go wrong. An exception would be the sentence " The elevator buttons are on the left", which is always true, if the elevator only opens to one direction.


Landmarks are spoken out loud during the navigation, when your path goes past one.

The format is following:

Then continue {{distanceInt}} {{distanceUnit}} towards {{title}}.

Then continue {{distanceInt}} {{distanceUnit}} passing {{title}} {{side}}.

You are passing {{title}} {{side}}.


Hazards are a warning on something.

The format these are read out loud is: "Watch out for {{title}} {{side}}." 

Note on directions

You may in some rare situations encounter a notification that seems out-of-place. For example, in this situation illustrated below, where the red arrows are illustrating your direction of walking. The notification that would be given to you is: "Watch out for Hazard: small ramp on your left."

Looking at the setup on the editor, this may seem incorrect to you. The hazard is clearly on the right side of the path. 

However, what you need to take into account is the range of the hazard. In this instance we have determined it as 5 meters. So the notification is already triggered in the point illustrated below with a red arrow. At that moment the hazard is indeed to the left from your location:

If you want to avoid this situation, make the range of the hazard smaller.

Note on visualizations

Remember to also decide, how you want to visualize all this information in your app. Should it be all visible in a text box, or would you want to use special colouring for example for warnings? The sample application visualizes all instructions in a default tect box.

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