You will notice that when people are talking in Gaelic and using each other’s names, the sound (and spelling) of most names change. This is called the vocative case.
Seòras becomes a Sheòrais.
Catrìona becomes a Chatrìona.
Names beginning with a vowel or l, n and r don’t change.
When someone calls your name, you should answer: Seadh. This is a bit like uh-huh in English.