The spelling of the word "wallsten" is phonetically transcribed as /ˈwɑːlstən/. The first syllable is pronounced as "wawl" with an elongated "a" sound like in "saw". The second syllable is pronounced as "sten" with a short "e" sound like in "pen". The consonants "l" and "t" are pronounced as written. Overall, the correct spelling of "wallsten" is crucial in accurately pronouncing and understanding the word.