The spelling of the word "swannack" can be explained using the International Phonetic Alphabet (IPA) transcription. The initial "s" is pronounced as /s/, followed by the "w" sound represented by /w/. The "a" is pronounced as an open-mid back unrounded vowel, /æ/. The consonant cluster "nn" is pronounced as /n/ followed by another /n/, and the final syllable ends with /æk/. Therefore, the phonetic transcription of "swannack" is /s w æ n n a k/.