The spelling of the word "Roysden" can be explained through its phonetic transcription in IPA. The word is pronounced as "rɔɪzdən", with emphasis on the first syllable. The "r" is pronounced with a slight trill of the tongue, followed by a long "ɔɪ" sound as in the word "boy". The "z" is pronounced with a voiced consonant sound, followed by a short "ə" sound as in the word "about". The final "n" is pronounced with a nasal sound at the end of the word.