"Sonancies" is a rare but valid word in English language that refers to musical harmony or a pleasing combination of sounds. The correct spelling of this word is /sənənsiz/ (suh-nuh n-seez), with the stress on the second syllable. The initial "s" is pronounced softly as a result of the following "o" being unstressed. This word follows the spelling pattern of "-ancies" as a suffix, which derives from the Latin "-antia" and means "having the quality of."
There doesn't appear to be information available about the word "sonancies". It is possible that it is a misspelling or a rare word with no widely recognized etymology.