The spelling of the surname "Claessens" can be a bit confusing due to its Dutch origin. In IPA phonetic transcription, it would be spelled /klaːsəns/. The two "s" sounds at the end are pronounced as a voiceless alveolar fricative, which means the sound is produced by forcing air through a small gap between the tongue and the roof of the mouth. Remembering this phonetic detail can help with the correct spelling of the name in written forms.