You can use notifications in Emacs > 24:
(require 'notifications)
(notifications-notify :title "Achtung!"
:body (format "You have an appointment in %d minutes" 10)
:app-name "Emacs: Org"
:sound-name "alarm-clock-elapsed")
(require 'notifications)
(notifications-notify :title "Achtung!"
:body (format "You have an appointment in %d minutes" 10)
:app-name "Emacs: Org"
:sound-name "alarm-clock-elapsed")