Which pioneering researcher made extensive use of nonsense syllables in the study of human memory?

Learning is affected by prior knowledge, that's why Ebbinghaus in his research used nonsense syllable: ROH, LEZ, SUW, QOV, XAR, KUF, WEP, BIW, CUL, TIX, QAP, WEJ, ZOD. These Words were new for him and he had no prior cognitive association.