The spelling of the surname "Ladwig" can be explained with the use of IPA phonetic transcription. The word begins with the consonant "l", which is pronounced as /l/. This is followed by the vowel sound "a", pronounced as /æ/. The next consonant is "d", pronounced as /d/. The word concludes with the combination of the voiced fricative "w" sound, pronounced as /v/, followed by the plosive "g" sound, pronounced as /g/. Hence, the phonetic transcription of "Ladwig" is /ˈlædwɪɡ/.