The figure of speech in the phrase "Fame shall sound thy praise from sea to sea" is personification. Personification is a figure of speech where human-like qualities are attributed to non-human things or abstract ideas. In this case, the abstract concept of fame is being personified by giving it the human-like ability to "sound" and "praise." Alliteration, on the other hand, refers to the repetition of initial consonant sounds in a series of words. While there is some alliteration present in the phrase (e.g., "Fame shall sound"), it does not define the overall figure of speech used.
