IPA: /ˌpɒlɪˈfɒnɪkli/
KK: /pɑːlɪˈfɒnɪkli/
In a way that involves multiple independent melodies or voices being sung or played at the same time.
The choir sang polyphonically, creating a rich and harmonious sound.
Polyphonically → It is formed from "poly-" (from Greek "polus", meaning many) and "phonic" (from Greek "phonē", meaning sound) combined with the suffix "-ally" (meaning in a manner). The word describes something that is done in a manner involving many sounds or voices.
Think of 'many' ('poly-') sounds ('phonic') coming together — that's what polyphonically means.