"Robertses" is the plural form of the surname "Roberts." Its spelling follows the general rule of adding "-es" to form the plural of a noun ending in "-s." In IPA phonetic transcription, it is pronounced as /ˈrɑːbərtsɪz/, with stress on the first syllable and a schwa sound in the second syllable. The "b" is pronounced with a slight aspiration, and the "t" is pronounced with a glottal stop in some dialects.