Janssens rhymes with:
hansen's, hanson's, manson's, aaronson's, ahmanson's, ahmansons, atkinson's, benson's, goldenson's, hansen's, hanson's, johnsen's, johnson's, johnsons, levinson's, manson's, parkinson's, robinson's, robinsons, robinsons', swensen's, wilkinson's, wisconsin's
Janssens sounds like:
jamaicans, jenkens, jenkins, jingsheng, jinkins, johnsen's, johnson's, johnsons, junghans, junking, junkins