@johncarlosbaez this bit caught my interest "It is believed that some medieval founders cast eccentrically shaped bells so that the frequency pairs were so far apart they would not beat." but the cited paper (Group Theory and The Bell, Journal of Sound and Vibration (1973) 31:411-418. R. Perrin, T Charnley.) seems to be paywalled everywhere.
eccentrically shaped medieval bells searching i go.