1) Locate an open a contact within your contacts folder
2) Select the contact's "Edit" or pencil icon within the contact's page/profile
3) Select the ring tone or sound location within your device's internal folder
4) Assign ring tones for that contact using the available ring tone or sounds.
5) If you do not see a ring tone of sound, Locate a sound effect site to acquire sound effects or create your own via a audio adjustment creator program.
Because I'm a bird watcher, I use common bird sounds or calls as it indicated who's calling me. if one is creative enough, they can record their own sound bites and add them to their device in an .MP3 format.