Viacom rhymes with:
belgacom, sodecom, stratacom, telecom, telekom, acecomm, beckom, belgacom, careercom, ficom, francom, genicom, globcom, incom, intelcom, metcom, micom, millicom, neukom, omnicom, opcom, secom, sodecom, stratacom, syncom, telecom, telekom, verticom, wascom
Viacom sounds like:
vaccine, vaccinia, vachon, vacuum, vagina, vaguine, vajna, vaughan, vaughn, vecchione, veegenan, vegan, vegesna, vesmen, vesna, vezina, viagene, vicino, vicon, vicuna, vigen, viggiano, vigna, vigneau, viscomi, vishnu, vision, vixen, vizcaino, vizzini, vogan, voisin, voisine, vossen