Insouciance rhymes with:
ambiance, ambience, audience, dalliance, deviance, disobedience, expedience, experience, inexperience, invariance, obedience, prescience, provenience, radiance, resilience, subservience, transience, variance
Insouciance sounds like:
imagines, imaging, imagining, immunizing, inasmuch, incense, inching, incisions, incomes, incoming, ingenious, ingenuous, innocence, inocencio, insomniac, ionizing