Table 2.

The set of acoustic warning messages.

Order of Relevance	Object Type	Distance to the VI User 1,2	Sound Pattern
1	vehicle	urgent	Urgent vehicle
2	bicycle	urgent	Urgent bicycle
3	vehicle	normal	Normal vehicle
4	pedestrian	urgent	Urgent people
5	obstruction	urgent	Urgent obstruction
6	bicycle	normal	Normal bicycle
7	pedestrian	normal	Normal people
8	obstruction	normal	Normal obstruction

¹ An object is marked as urgent if its associated distance relative to a VI user is inferior to 2 m, otherwise is considered as normal; ² An object is considered as approaching the subject if the associated distance between successive frames is decreasing, otherwise is marked as departing the VI person.