sound-substitutev. [as a back-formation] (transitive) to replace (one phoneme) by another (rare).
ΘΚΠ
the mind > language > linguistics > study of speech sound > speech sound > [verb (transitive)] > classify or describe in terms of phoneme theory > replace one phoneme by another
sound-substitute1953
1953 K. JacksonLang. & Hist. in Early Brit.ii. 558 A possible case of pre-lenition bsound-substituted by AS. ƀ.