The vocative case is used when addressing someone directly. There were three examples in Conversation 1D:
Bonnleibheal_1/Aonad_1/EU12_01.mp3 a Shéamais
SéamasBonnleibheal_1/Aonad_1/EU12_02.mp3 a Shiobhán
SiobhánBonnleibheal_1/Aonad_1/EU12_03.mp3 a Mháire
Máire
Changes occur to the beginning of many Irish language names, both male and female, in the vocative case and also to the end of some male names.