Janssen rhymes with:
jansen, janson, jansson, ansohn, anson, branson, canson, danson, fransen, franson, franssen, gansen, ganson, hansen, hanson, hanssen, hansson, jansen, janson, jansson, johannsen, johansen, johanson, manson, ranson, ransone, sanson, sansone
Janssen sounds like:
jainism, jamaican, jameson, jamieson, jamison, jansen, jansma, janson, jansson, janzen, jeansonne, jemison, jenison, jenkin, jennison, jensen, jenson, jenssen, jimison, jingoism, johannesen, johannessen, johannsen, johansen, johanson, johansson, johnsen, johnson, jonassen, jonsman, jonson, jonsson, jungin, jungman, junkin, junwuxiyan