Correct spelling for the English word "hyphedonia" is [hˌa͡ɪfɪdˈə͡ʊni͡ə], [hˌaɪfɪdˈəʊniə], [h_ˌaɪ_f_ɪ_d_ˈəʊ_n_iə] (IPA phonetic alphabet).
An habitually slight degree of pleasure caused by occurrences that should normally give great pleasure.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.