Sondheim's rhymes with:
waldheim's, durkheim's, waldheim's, anytime's, centimes, daytimes, durkheim's, enzymes, halftimes, lifetime's, lifetimes, maritimes, nighttimes, oftentimes, paradigms, pastimes, pulmazyme's, showtime's, waldheim's, wartimes, windchimes
Sondheim's sounds like:
sanding, sandino's, sandness, scantiness, sending, sentence, sentences, shandong, shantytowns, shunting, smeeting, smoothens, smoothing, smoothness, something, something's, somethings, sometimes, sounding, soundings, soundness, squinting, sumitomo's, summations, sundance