it's possible play a music when you see a enemy(see int he screen)

[anonymous_user_cb7e9863]

Check the next links. They should give you an idea how to do it:

https://docs.unrealengine.com/latest/INT/Gameplay/HowTo/UseRaycasts/Blueprints/index.html
https://docs.unrealengine.com/latest/INT/BlueprintAPI/Utilities/Transformation/GetDistanceTo/index.html

Getting distance between two vectors in Blueprint?